NXP MC13201, MC13202, MC13224V, MC13213, MC13203, MC13214, MC13211, MC13212 Reference guide

NXP MC13201, MC13202, MC13224V, MC13213, MC13203, MC13214, MC13211, MC13212 Reference guide
Freescale IEEE 802.15.4 / ZigBee
Node RF Evaluation and Test
Guidelines
Reference Manual
Document Number: ZRFETRM
Rev. 1.0
05/2010
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Contents
About This Book
Audience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii
Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii
Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii
Recommended References and Reading. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
Chapter 1
Guidelines for the Successful Hardware Development of an IEEE 802.15.4 / ZigBee
Wireless Node
1.1
1.2
1.3
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
Design Flow Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
What This Reference Manual Covers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Chapter 2
RF Design Validation and Verification
2.1
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
2.2
Preparing for RF Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
2.2.1
RF Test Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
2.2.2
Preparing the Module for RF Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
2.2.3
Crystal Reference Oscillator Characterization and Trim . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
2.3
Transmitter (TX) Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
2.3.1
TX Measurement Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
2.3.2
Transmit Power. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
2.3.3
Out-of-Band Spectrum Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
2.4
Receiver (RX) Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
2.4.1
Measurement Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8
2.4.2
Packet Error Rate (PER) to Measure Receiver Sensitivity. . . . . . . . . . . . . . . . . . . . . . . . . . 2-8
2.4.3
Energy Detect and Link Quality Indication (LQI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9
2.5
Recommended Software for Validation and Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10
2.6
Board-to-Board / Range Testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11
2.6.1
Evaluating Board-to-Board Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11
2.6.2
Using Freescale Software for Board-to-Board Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12
2.6.3
Quantifying PER Test Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13
2.6.4
Range Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-16
Chapter 3
FCC Pre-Certification/Certification
3.1
3.2
3.2.1
3.2.2
3.2.3
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Planning for Certification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Choosing the Correct Certification Lab is Important . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Include Certification Requirements/Activities in the Design Flow . . . . . . . . . . . . . . . . . . .
Alternatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-1
3-1
3-1
3-2
3-2
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3.2.4
3.3
3.3.1
3.3.2
3.3.3
3.3.4
3.3.5
3.3.6
3.3.7
3.3.8
3.4
Suggested Reading / References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
Pre-Certification Testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
Measurement Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
Peak Output Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
Spurious Emissions - Conducted (basic) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5
Conducted Spurious Emissions Band Edge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7
Spurious Emissions - Radiated (basic) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8
Radiated Spurious Emissions Band Edge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11
Duty Cycle Correction Factor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13
Power Spectral Density (PSD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-14
Getting Certification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-15
Chapter 4
Production Test Guidelines
4.1
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
4.2
Production Test Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
4.3
Freescale Tools to Support Production Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
4.4
Programming a Test Application or NVM Image . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
4.4.1
HCS08 Platforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
4.4.2
ARM7 Platforms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
4.4.3
Updating or Reloading of NVM Image . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4
4.5
Communication Between Tester Platform and DUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5
4.6
Crystal Testing and Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5
4.6.1
HCS08 Platforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6
4.6.2
ARM7 Platforms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6
4.7
RF Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7
4.7.1
Recommended Production RF Tests. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7
4.7.2
RF Test Means and Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7
4.7.3
Test Instrumentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8
4.8
Production Data and MAC Address Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8
4.8.1
HCS08 Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9
4.8.2
ARM7 (MC1322x) Parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-13
4.9
Simple Overview of Test Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-16
Appendix A
Freescale 802.15.4 RF Test Software
A.1
A.1.1
A.1.2
A.2
A.3
A.4
Test Applications and Tools Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Target Applications for RF Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PC Host Application for Test (Test Tool) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SMAC Test Applications for HCS08 Platform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
22xSMAC Test Application for ARM7 Platform (Connectivity Test) . . . . . . . . . . . . . . . . . . .
ZigBee Test Client (ZTC). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-1
5-1
5-2
5-2
5-3
5-4
802.15.4/ZigBee RF Evaluation and Test Reference Manual, Rev. 1.0
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Appendix B
RF Test Modes in The MC1320x and MC1321x Transceivers
B.1
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B.2
SPI Registers That Support RF Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B.3
Programming the Transceiver for Test Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B.3.1
Transmitter Test Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B.3.2
Receiver Test Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6-1
6-1
6-2
6-2
6-4
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About This Book
This manual describes Freescale’s RF evaluation and test recommendations for developers of wireless
IEEE 802.15.4 Standard nodes.
Audience
This manual is intended for system and hardware designers and test engineers responsible for developing
products using Freescale IEEE 802.15.4 technology which supports various software applications
including ZigBee, ZigBee RF4CE, and custom Freescale stacks.
Organization
Freescale provides a large number of design resources from reference manuals, reference designs,
application notes, software applications and tools.
This document is organized as follows:
Chapter 1
Guidelines for the Successful Hardware Development of an IEEE 802.15.4 /
ZigBee Wireless Node - Provides an overview of a recommended hardware design
flow and makes designers aware of available Freescale design resources.
Chapter 2
RF Design Validation and Verification - Provide in depth means and methods for
doing RF debug and evaluation including recommended equipment and available
Freescale software tools.
Chapter 3
Chapter 4
Appendix A
Appendix B
FCC Pre-Certification / Certification - Provide an overview of FCC certification
requirements and process and discuss means and available tools to implement the
process.
Production Test Guidelines - Describes manufacturing test recommendations for
products that employ Freescale IEEE® 802.15.4 Standard wireless technology.
Freescale 802.15.4 RF Test Software - The RF test software ranges from simple
standalone applications running on the target board to more capable and
sophisticated tools that use a client application running on the target board with
host application running on a personal computer (PC).
RF Test Modes in The MC1320x and MC1321x Transceivers - Provides reference
information on the listed devices for enabling RF test modes.
Revision History
The following table summarizes revisions to this document since the previous release (Rev 0.0).
Revision History
Location
Entire Document
Revision
Updates throughout and added Chapter 4.
802.15.4/ZigBee RF Evaluation and Test Reference Manual, Rev. 1.0
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iii
Definitions, Acronyms, and Abbreviations
The following list defines the acronyms and abbreviations used in this document.
ADC
Analog to Digital Converter
AES
Advanced Encryption Standard
ARM
Advanced RISC Machine
CTS
Clear to Send
DAC
Digital to Analog Converter
DCCF
Duty Cycle Correction Factor
DMA
Direct Memory Access
I2C
Inter-Integrated Circuit is a multi-master serial computer bus
ISM
Industrial Scientific Medical 2.4 GHz radio frequency band
JTAG
Joint Test Action Group
LGA
Land Grid Array
MAC
Media Access Controller
MCU
Microcontroller Unit
NEXUS
An embedded processor development tool interface that helps design engineers
identify software and hardware-level issues.
PCB
Printed circuit board
PiP
Platform in Package
PSDU
PHY service data unit
PWM
Pulse-width modulation
RTS
Request to Send
SMA Connector
SubMiniature version “A” connector
Single-ended
An RF port on a transceiver that is a single input/output pin as opposed to a
differential RF port.
SPI
Serial Peripheral Interface
SSI
Synchronous Serial Interface
TACT Switch
A switch that provides a slight “snap” or “click” to the user to indicate function.
Target Application
Customer specific application intended for the customer module
TELCO
Telephone Company
USB
Universal Serial Bus
VCP
Virtual Com Port
802.15.4/ZigBee RF Evaluation and Test Reference Manual, Rev. 1.0
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Recommended References and Reading
•
•
•
•
“Simplifying FCC Compliance for 802.15.4 2.4 GHz devices”, National Technical Systems,
www.ntscorp.com
ETSI EN 300 440-1, V1.3.1 (2001-9), “Electromagnetic compatibility and Radio spectrum Matters
(ERM); Short range devices; Radio equipment to be used in the 1 GHz to 40 GHz frequency range;
Part 1: Technical characteristics and test methods”, European Standard (Telecommunications
series), Reference REN/ERM-RP08-0406-1.
Code of Federal Regulations Title 47 - Telecommunication: Part 15 - Radio Frequency Devices.
Available in electronic and PDF formats from the FCC web site.
"Measurement of Digital Transmission Systems Operating under Section 15.247" FCC Publication
558074.
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Chapter 1
Guidelines for the Successful Hardware Development of an
IEEE 802.15.4 / ZigBee Wireless Node
1.1
Introduction
The growth of low cost, low power wireless nodes based on the IEEE® 802.15.4 Standard has been
expanding rapidly. Freescale provides devices, software, platforms, and extensive design collateral to ease
design development, speed time-to-market, and minimize design errors. A 2.4 GHz wireless node,
however, can be somewhat intimidating to those users that have had little or no experience with RF design.
The good news is that RF circuitry is minimized by today’s integrated radios and that Freescale provides
extensive design support for the user.
The purpose of this manual is to help guide the new user of Freescale 802.15.4 devices (radios) through
the process of turning their application into a qualified printed circuit board (PCB) by understanding the
potential pitfalls of RF design and by using the Freescale design aids. A simple hardware design flow is
presented with emphasis on radio design and testing.
1.2
Design Flow Overview
The designer is encouraged to use the following simplified design flow that emphasizes the hardware RF
considerations:
1. Determine which Freescale device/platform best meets the user’s needs - Freescale supplies
three primary families of devices (see Table 1-1). Software stacks, development boards/kits, and
design collateral are available for all these families. It is not the intent of this manual to help
determine this selection, other than to emphasize this as a first step.
Table 1-1. Summary of Freescale IEEE® 802.15.4 Families
Family
Description
Comments
MC1320x
Fully compliant 802.15.4 transceiver (no onboard MCU) • Freescale stacks support 8-bit MC9S08x including
the MC9S08QE128
• Usable with other Freescale MCUs
MC1321x
Fully compliant 802.15.4 transceiver (MC13202
equivalent) integrated with a MC9S08A MCU die in a
single package
• Freescale stacks fully support this device
• Standalone device - needs no other MCU
• Based on the 8-bit MC9S08 MCU
MC1322x
Fully integrated ARM7 MCU and transceiver in a single
device.
•
•
•
•
Freescale stacks fully support this device
Standalone device - needs no other MCU
Based on the 32-bit ARM7 MCU
Lowest power
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1-1
Guidelines for the Successful Hardware Development of an IEEE 802.15.4 / ZigBee Wireless Node
2. Select a Freescale Reference Design as a baseline for a board schematic and layout - Freescale
has specific reference designs available for ALL devices and their variations with regard to antenna
and board types. Freescale emphasizes the importance of using reference designs to achieve a
quick-turn, successful target PCB.
— Reference designs have been built and verified. RF performance is greatly impacted by board
parameters (metal/dielectric thickness, permittivity, and stackup), component placement,
interconnect geometries, and ground topology
— Complete design databases and documentation are provided including schematics and layouts
as well as BeeKit configuration files for easy integration into the BeeKit environment
— The package footprints on the reference layouts have been designed for reliable solder reflow
processes
— The reference design can be used “as-is” for simple applications or used as a starting point for
the board stackup, RF circuitry placement and design, and the 802.15.4 device layout. From the
starting point the user can then expand the design to include his unique peripheral devices and
circuitry.
— Reference designs vary from full featured development boards to minimal area, simple
modules
— Both 2-layer and 4-layer metal designs are available
Table 1-2 is a summary list of available reference designs.
NOTE
This may not be a comprehensive list. Check with the Freescale website
www.freescale.com/zigbee under “802.15.4 and ZigBee® Hardware
Reference Designs” for a current list of available designs. There are two
types of reference designs listed:
•
Module Reference Design - that contains a minimal amount of
peripheral circuitry
• Development Board Reference Design - that document Freescale's
802.15.4 development hardware.
It is recommended that a Module Reference Design be selected as the
starting point for an OEM design.
Table 1-2. Summary of Freescale 802.15.4 and ZigBee® Hardware Reference Designs
Reference
Design
Family
Description
1320x-RFC
MC1320x
Transceiver only development board reference design. Daughter card for use with an
MCU.
1320x-QE128-EVB
MC1320x
Development board reference design for MC1320x and MC9S08QE128
1320x-QE128-IPB
MC1320x
Module reference design for MC1320x and MC9S08QE128 using an RF interface with a
balun and PCB “F” antenna
1321x-SRB
MC1321x
Development board reference design for sensor node
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Guidelines for the Successful Hardware Development of an IEEE 802.15.4 / ZigBee Wireless Node
Table 1-2. Summary of Freescale 802.15.4 and ZigBee® Hardware Reference Designs
Reference
Design
Family
Description
1321x-NCB
MC1321x
Development board reference design for network node
1321x-IPB
MC1321x
Module reference design for MC1321x using RF interface with a PCB “F” antenna
1321x-ICB
MC1321x
Module reference design for MC1321x using an RF interface with a balun and a chip
antenna
1321x-USB
MC1321x
USB stick reference design for MC1321x using an RF interface with a balun and a chip
antenna
1322x-SRB
MC1322x
Development board reference design for sensor node
1322x-NCB
MC1322x
Development board reference design for network node
1322x-USB
MC1322x
Development board reference design for USB stick
1322x-LPB
MC1322x
Development board reference design for low power node
1322x-IPB
MC1322x
Module reference design for MC1322x using single-ended RF interface with a PCB “F”
antenna
1322x-ICB
MC1322x
Module reference design for MC1321x using single-ended RF interface with a chip
antenna
3. Design/layout target application board using the selected Reference Design baseline - For
simple end node applications a reference design such as an “IPB” or “ICB” may be very close to
the desired final product. In contrast, a complex network coordinator node may take advantage of
a more complex reference design such as an “NCB” or “SRB” with major modifications. Key
points to consider:
— Use the provided 802.15.4 device package footprint including crystal, and power supply
connections.
— Use RF components, layout, and board stackup as provided. Dielectric thickness is part of the
antenna design. Changing the thickness will require antenna tuning that is beyond the scope of
this application note.
— For each Freescale 802.15.4 device there is a respective Reference Manual, The “System
Considerations” chapter is an excellent source of design considerations.
— Use a properly specified or recommended crystal for the reference oscillator (see AN3251,
“Reference Oscillator Crystal Requirements for the MC1319x, MC1320x, MC1321x, and
MC1322x”).
— Prepare for official certification
– Choose a certification house as a partner (see Section 3.2.1, “Choosing the Correct
Certification Lab is Important”) early in the process
– Solicit advice for RF requirements for targeted market countries
— Adding test points or connectors for the following can assist RF test:
– Reference clock output (CLKO for HC9S08/transceiver platforms or TMR1 for MC1322x
platforms)
– UART port (include flow control)
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Guidelines for the Successful Hardware Development of an IEEE 802.15.4 / ZigBee Wireless Node
— Consider adding design accommodations such as test points and others connections for RF test.
— Modify or add to the reference design peripheral circuitry as required by the target application.
For designs using the MC1320x devices, the signal connections between the transceiver and
target MCU should be left “as-is” so that porting Freescale-supplied applications is simplified
as much as possible.
NOTE
In addition to specific device data sheets and reference manuals, Freescale
provides extensive support material to assist design decisions. Table 1-3
provides only a partial list of relevant support documentation. The user is
encouraged to scan the Freescale documentation available at
www.freescale.com/zigbee for additional material that may be use to a
particular application.
Table 1-3. Relevant 802.15.4 Hardware Design Resources
ID
ZHDCRM
Title
Description
Freescale IEEE 802.15.4 / ZigBee Hardware
Design Considerations Reference Manual
• Provides package information including metal layout,
solder mask, and solder paste recommendation.
• Solder reflow recommendations
• Tape and reel info
• Key chapter on RF design and layout
considerations
AN2975
Range Extension for IEEE® 802.15.4 and
ZigBee™ Applications
application note defines IEEE 802.15.4 PHY layer
parameters and provides discussion of RF component
selection
AN2731
Compact Integrated Antennas Designs and Applications for the MC1319x,
MC1320x, and MC1321x
• application note discusses use and tradeoffs of
different antenna types
• Provides detailed information on Freescale’s
recommended “F” antenna
AN3251
Reference Oscillator Crystal Requirements
for the MC1319x, MC1320x, MC1321x, and
MC1322x
application note provides crystal specifications,
recommended crystals, and design information for all
Freescale 802.15.4 device reference oscillator crystals
4. Build prototype PCB; debug and evaluate/verify RF performance - After the design is
complete, first prototype boards are built. A structured approach is suggested for debug (as
opposed to first loading the target software and trying to do debug with the complete application):
— Do an initial visual inspection
– Are all required components in place?
– Inspect the 802.15.4 device and the reference crystal for orientation. With a square package
outline, it is not uncommon for components to be improper placed; rotated by 90°
— Power-up the board and check power supply(s)
– Are voltages correct?
– Are currents within expectations?
– Are all VDD supply pins getting voltage (any opens)?
– Are there any shorts?
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Guidelines for the Successful Hardware Development of an IEEE 802.15.4 / ZigBee Wireless Node
— Check basic operation with and w/o reset active
– With reset active, is current draw within expectation?
– After release of reset, does the MCU or device reference oscillator start properly and is it on
frequency?
— Establish connection between the development tools and the debug port
– With MC9S08 platforms this is the BDM port
– With the MC1322x platform this is the ARM7 JTAG port
– Download a simple test application and establish communication and control of the target
board
NOTE
For prototype boards:
•
First builds for new process flows are recommended to be a limited
number of boards
• The 802.15.4 device packages are small and have small pads/pins with
tight pad pitch
• Solder reflow temperatures are limited to 260°C or less. This requires
that reflow temperature profiles be carefully developed and maintained
because RoHS standards use higher temperature solder.
Because of these factors, it is possible to have opens or shorts with the
device connections. If initial target board failures are found, first thoroughly
investigate device connections for opens and shorts because the
manufacturing process may need adjusting.
At this juncture, once proto boards are generally functional, common practice is to continue
development in a somewhat parallel approach:
— Provide boards for software development
— Debug custom application hardware (sensors, peripherals, power management, etc)
— Test and evaluate RF performance
It is to be emphasized that the RF test and evaluation should be a separate focused activity and
independent of the user’s target software. This is possible because Freescale provides software
tools/applications for test that are easily applied to the target board. In this manner basic RF
operation can be evaluated in a methodical manner and any impact from the target software can be
eliminated.
5. Design Phase RF test and evaluation - This activity will first evaluate transmitter and receiver
performance. Once these are independently evaluated, and corrected as needed, end-to-end RF
performance is checked via packet error rate (PER) testing. Chapter 2 of this reference manual is
an in-depth discussion of testing techniques and tools for developing a qualified RF design.
6. FCC pre-certification / certification - Once the RF and application performance of the target
board is considered qualified, a wireless product must become government certified for the
countries / markets in which the product will be sold. In the United Stated the product must be
Federal Communications Commission (FCC) certified. This process is generally considered a
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Guidelines for the Successful Hardware Development of an IEEE 802.15.4 / ZigBee Wireless Node
two-stage process consisting of pre-certification and actual certification. Chapter 3 of this
reference manual is an in-depth discussion of the certification process and available Freescale tools
that can assist in certification of wireless design.
7. Production test - Test during production must verify operation of the module with a minimum of
test time and resources to keep cost low, but still provide suitable validation. Chapter 4 of this
reference manual is a discussion of the suggested techniques and recommended software
applications that can be modified for customer use.
1.3
What This Reference Manual Covers
Although this chapter presents a recommended hardware design flow, the manual is not intended as an
applications “how to” design guide. The following chapters on RF evaluation and certification do provide
hands-on information about equipment, tools, and means to debug and qualify the RF circuitry, and then
officially FCC certify a final product. As a final subject, the manual provides information and guidelines
for production test.
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Chapter 2
RF Design Validation and Verification
2.1
Introduction
As covered in Chapter 1, RF test and evaluation should be done as a separately focused activity. This
should be performed to eliminate any possible dependencies between software and hardware. It is best that
software used to evaluate RF performance be simple test application(s), not the target communications
software where there can be unknowns as to the source of any problems.
RF functionality can be tested in an orderly manner. Very simplistically, there is:
• RF transmission (TX)
• Reception (RX)
• End-to-end performance
A wireless node can only be doing one function at-a-time, i.e., transmission or reception. Each can be
evaluated independently, and then, the complete end-to-end connection can be evaluated.
Before proceeding with RF test, consider the following:
• It is recommended that the test engineer have a good working knowledge of the IEEE® 802.15.4
Standard PHY layer specification:
IEEE Std 802.15.4™-2003, Part 15.4: Wireless Medium Access Control (MAC) and Physical Layer
(PHY) Specifications for Low-Rate Wireless Personal Area Networks (WPANs), 2006
The 802.15.4 PHY has several frequency bands, but the devices of interest deal only with the 2450 MHz
PHY. The user should become familiar with all the details of over-the-air signals; modulation means and
spectrum, packet construction and format, transmitter and receiver specifications, etc.
• RF characteristics can be measured by two general means, i.e., over-the-air and direct connection.
Direct connection is highly recommended because over-the-air measurements are very difficult to
perform as well as quantify; over-the-air performance is highly dependent on antenna efficiency,
direction, distance between the TX node and the RX node, and environmental interference. The
purpose here is to measure the quality of the RF signal at the antenna.
• Use a Freescale provided software tool/application as a starting point for developing RF test
applications. The suggested software is discussed in a following section. Also, using test software
(which is required) implies some level of software support to the RF test engineer.
802.15.4/ZigBee RF Evaluation and Test Reference Manual, Rev. 1.0
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2-1
RF Design Validation and Verification
NOTE
Although the onboard RF circuitry of the 802.15.4 platforms and available
Freescale applications support helps minimize the design and test effort to
produce a working 2.4 GHz wireless node, it still requires a serious
commitment in resources and equipment to validate and support the final RF
design. If the user has minimal or no previous experience with RF design
and test, he can consider using consulting services and/or pre-manufactured
and certified modules as an end-use alternative.
2.2
Preparing for RF Testing
Once the module has been through preliminary debug and functional verification (as explained in Step 4
of the basic design flow), some suggested preparation for RF testing is presented in this section.
2.2.1
RF Test Equipment
To do RF test at 2.4 GHz frequency requires having some minimal level of required equipment which can
be expensive, so the rent vs. buy option may be considered by the user.
A minimal list of measurement equipment is suggested in Table 2-1. The listed instruments or equivalent
equipment is suitable.
Table 2-1. Typical Equipment Options for PHY Layer Tests
Vendor Options
Type
Quantity
Comments
Model Number
Manufacturer
RF Power Meter
1
E441X
Agilent
Signal Generator
2
SMIQ Family
Rhode &
Schwarz
Requires user programming
SMU200A
Rhode &
Schwarz
Requires user programming. application
note available
E443X
Agilent
Requires user programming
N4010A
Agilent
Option 102 available for 802.15.4
RF Frequency counter
Frequency Counter
1
53181A
Agilent
Power Meter Sensor
1
E9323A
Agilent
Vector Signal Analyzer
1
N9020A
Agilent
N4010A
Agilent
Digital Multimeter
1
Integrated 802.15.4 Test Set
1
Any
Custom
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RF Design Validation and Verification
2.2.2
Preparing the Module for RF Test
Quantified RF measurements are best done via a connected path rather than over-the-air means. This
requires that some form of hardwired connection be available on the board to attach equipment. There are
several common ways this may be achieved:
• The board layout provides a wiring option for an RF connector - In this situation, the RF signal
trace is ac-coupled through a capacitor to the antenna, and a second path to a connector (typically
an SMA connector) is also available via an ac-coupled option. When using the board for test, the
coupling cap to the antenna is removed, and the path to the RF connector is enabled through a
second coupling cap. The connector must also typically be mounted as it is not normally in place.
In order to minimize unwanted RF effects, it is best to share the common side of the capacitor pads
This avoids having an open circuit stub hanging off of the RF path not used.
J2
0-18GHZ
G3
G2
G4
1
G1
DNP
RF_SMA
C1
10PF
DNP
C2
RF_ANT
RF_TX_RX
10PF
ANT2
F_Antenn a
Figure 2-1. Wiring Option for RF Connector
•
A special “microwave coaxial connector with switch” (similar to the Murata MM8130-2600 or
Amphenol MCX series) can be inserted between the RF signal trace and the antenna - This is also
a design/layout option that must be part of the board design. This connector/switch is surface
mounted and normally sits in the RF signal path. When a special measurement probe is attached,
the signal path to the antenna is opened and connected through the probe. In this manner, there is
no board alteration done and good RF connection is made. This approach does have the
disadvantage of being more expensive. However, it is possible to replace the connector with a
capacitor for production runs.
J3
1
4
2
5
3
6
C13
RF_TX_RX
10PF
SW F Sw Coax C onn
ANT3
F _Antenna
Figure 2-2. In-line Coaxial Connector with Switch
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RF Design Validation and Verification
•
Altering the board for test purposes - an RF connector (typically SMA) can be soldered to the board
and connected to the RF signal trace. Two general means are used to do this:
— The connector is soldered to the board via very short “pigtails”. The ground shield connection
should be as short as possible or can be soldered directly to the board ground. The RF signal
should be wired to the RF connector center conductor with as short a wire as possible.
— Cut away the antenna (in these examples, an “F”-antenna is used) such that the SMA connector
center conductor can be directly soldered to the antenna feed wire and the connector ground is
directly wired to the board ground.
2.2.3
Crystal Reference Oscillator Characterization and Trim
The IEEE 802.15.4 Standard requires that the frequencies and symbol rates associated with the radio
transmit and receive functions have an accuracy of +/-40ppm or better. With properly specified crystals,
the Freescale devices can maintain a typical accuracy of +/-30ppm or better over temperature and voltage
variation.
At this juncture, it is recommended that the reference oscillator of the target be characterized, and as
required, the nominal frequency be centered for the MC1320x, MC1321x, and MC1322x devices.
NOTE
The following sections describe general procedures for characterizing the
device reference oscillator. Different software tools provide capability to
adjust the oscillator trim capacitance and monitor the reference oscillator
accuracy (ppm). The user should refer to the particular application reference
documentation for details on using that application (see Table A-1).
2.2.3.1
MC1320x and MC1321x 16MHz Transceiver Reference Oscillator
Characterization
The 20x and 21x devices have a fixed 16MHz reference oscillator. The capacitive loading for the oscillator
is provided primarily by discrete capacitors (see AN3251, “Reference Oscillator Crystal Requirements for
the MC1319x, MC1320x, MC1321x, and MC1322x”) and is trimmed by onboard capacitors.
To characterize the oscillator performance:
• The device initializes with the onboard trim capacitance set to mid-range (SPI Register 0x0F,
Bits[15-8] = 0x7F), i.e., about 2.4pF per side. At first, do not alter the default value.
• Monitor the frequency accuracy at output pin CLKO. The desired accuracy is less than +/-5ppm
without altering the default onboard trim.
• As required, adjust the external load capacitors to center the reference frequency as close to
nominal as possible. Increasing capacitance lowers frequency.
• Once the discrete load capacitance is determined, the trim value can be adjusted to “zero” the
frequency error.
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RF Design Validation and Verification
NOTE
With prototype modules, these results should be checked across several
boards. Later, when production volume is imminent characterizing the
reference oscillator across a large sample of modules is recommended to
determine typical variation and any in-production test or correction.
2.2.3.2
MC1322x 24MHz (Nominal) Reference Oscillator Characterization
The 22x device has a nominal 24MHz reference oscillator (this frequency is most common although
13-26MHz is usable). The capacitive loading for the oscillator is provided and trimmed completely by
onboard capacitors.
To characterize the oscillator performance:
• Out of reset, the device initializes with the onboard trim capacitance set to no load (Register
XTAL_CNTL 0x8000_3040, Bits[25-16] = 0x000). However, the software application usually
initializes the crystal tuning with a default value that is determined when the application is
configured at compile time.
• Monitor the frequency accuracy at a timer output pin (TMRx) as determined by the application
software, typically TMR1. The MC1322x has no dedicated clock output monitor pin, so this
function must be provided by a counter as enabled by the test software.
• Adjust the onboard load capacitance to center the reference frequency as close to nominal as
possible. Increasing capacitance lowers frequency.
NOTE
With prototype modules, these results should be checked across several
boards. Later, when ramping up production, characterizing the reference
oscillator across a large sample of modules is recommended to determine
typical variation and any in-production test or correction.
2.3
Transmitter (TX) Tests
The transmitter test list includes the following parameter measurements:
• Transmit Power
• Out-of-band Spectrum
NOTE
The TX test descriptions give general test background and procedures.
However, use the Freescale provided test software to establish these
conditions.
2.3.1
TX Measurement Equipment
The required equipment list for the transmitter tests is shown in Table 2-2. All measurements may be done
with a spectrum analyzer or a vector signal analyzer (VSA). The Error Vector Magnitude (EVM)
measurements must be done on the VSA.
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RF Design Validation and Verification
Table 2-2. Equipment Required for Transmitter Tests
Test Parameter
Power Spectral Density
Spectrum Analyzer
Vector Signal Analyzer
1
1
Error Vector Magnitude
2.3.2
1
Transmit Center Frequency Tolerance
1
1
Transmit Power
1
1
Transmit Power
The following quoted text is taken from the 802.15.4-2003 Standard:
“A compliant transmitter shall be capable of transmitting at least -3dBm. Devices should transmit lower
power when possible in order to reduce interference to other devices and systems. The maximum transmit
power is limited by local regulatory bodies.”
NOTE
The 802.15.4 specification refers to power as measured using a "band
power" technique with a 2 MHz bandwidth under modulated conditions.
However, certification testing is measured as peak power so it is
recommended that a peak power technique be used. This is the power
measured using a spectrum analyzer or peak-reading power meter.
The nominal output power is typically 0dBm, and commonly, maximum output power is about +3 to
+4dBm. This power may be specified at the package “edge” or to the antenna. Transmit power can be
measured in various modes:
• Unmodulated Continuous (CW) - this mode produces the highest peak power with minimum
channel bandwidth. This is also not a “real’ operational mode, but it may be useful for debugging
potential transmitter problems
• Modulated Continuous - this mode is useful for power measurement because it is continuous and
modulated. However, the symbol stream may not be highly randomized. Use this mode for FCC
pre-certification in Chapter 3, “FCC Pre-Certification/Certification”
• 9th Order Binary Polynomial (PRBS9) - this mode has a pseudo-random symbol stream that
provides best observation of the modulation spectrum. It is normally a packetized mode, however
and, the spectrum analyzer must be synchronized to the packets. Use this mode in Chapter 3 to
determine Duty Cycle Correction Factor (DCCF)
The output power is measured using the following steps:
1. Set channel frequency.
2. Enable TX mode (typically either modulated continuous or PRBS9).
3. Enable the transmitter.
4. Measure output power on spectrum analyzer - Absolute peak power.
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RF Design Validation and Verification
Figure 2-3. PRBS9 Signal with Synchronized Spectrum Analyzer
2.3.3
Out-of-Band Spectrum Measurement
The out-of-band spectrum requirements or spurious emissions are discussed extensively in Chapter 3 on
FCC Certification. At this point in the module evaluation, it is recommended to take an initial look
primarily at the TX spectrum 2nd and 3rd harmonics. The out-of-band spurious emissions including the
2nd and 3rd harmonics magnitude are required to be no greater than -41dBm absolute. Additional filtering
for a harmonic may be required in the form of a frequency trap.
2.4
Receiver (RX) Tests
The receiver test list includes the following measurements:
• Packet Error Rate (PER) - is used as the measurement criteria for the following tests:
— Receiver Sensitivity
— Adjacent and Alternate Channel Rejection
• Energy Detect - is used as the measurement criteria for:
— Clear Channel Assessment (CCA)
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RF Design Validation and Verification
— Link Quality Indication
NOTE
The RX test descriptions give general test background and procedures,
however, specific means of attaining the required transceiver state are not
described as these are done via the test software in use.
2.4.1
Measurement Equipment
The test environment setup for receiver testing consists of one or two signal generators whose output are
connected to the RF input of the receiver through a signal combiner. Testing is based on the concept of
Packet Error Rate where a known good transmitter sends packets to the receiver/device under test (DUT).
A vector signal generator is required to send/transmit the packets. Table 2-1 show four difference families
of vector signal generators. These divide into two categories:
• Requires user programming for 802.15.4 protocol - manufacturers do have applications
information available, but the user must program/setup the transmitter
— 802.15.4 modulation scheme and proper type of filter
— Proper packet size and format to meet the 802.15.4 Standard requirements for PER
• 802.15.4 support option available - the Agilent N4010A instrument does have a support option
available.
NOTE
Programming of a specific signal generator is beyond the scope of this
manual. It is the user’s responsibility to provide the required functionality
for 802.15.4 testing.
2.4.2
Packet Error Rate (PER) to Measure Receiver Sensitivity
Table 2-3 defines PER and receiver sensitivity and sets test conditions. PER uses a transmitter to send a
stream of packets and the receiver is tested to see the “average fraction of transmitted packets that are not
detected”. The PER testing is qualified by the following;
• Packet size is set - the PHY Service Data Unit (PSDU) length = 20 octets (2 symbols)
• PER shall be < 1%
• Interference is not present
The measurement is conducted using a known good transmitting board connected to the test receiving unit
via coaxial cable and an attenuator. The attenuator is used to set the desired power input level to the
receiver at which the PER is to be measured. Consecutive passes at various power levels (attenuator
settings) will be required to accurately measure the sensitivity.
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Table 2-3. PER and Receiver Sensitivity Definitions
Term
Definition of Term
Conditions
Packet Error Rate (PER) Average Fraction Of Transmitted Packets
That Are Not Detected
Average Measured Over Random PSDU Data
Receiver sensitivity
•
•
•
•
Threshold input signal power that yields a
specified packet error rate.
PSDU length = 20 octets.
PER < 1%.
Power measured at antenna terminals.
Interference not present.
The following quoted text and table are also taken from the 802.15.4 Standard:
“Under the conditions specified in [Table 2-3], a compliant device shall be capable of achieving a
sensitivity of -85 dBm or better.”
A receiver sensitivity test cycle is composed of the following steps:
1. Set channel frequency
2. Enable the receiver
3. Signal generator sends random PSDU data
4. Received number of packets are tabulated; these are compared to transmitted number of packets to
yield the PER percentage.
This cycle is repeated while altering the power level of the signal generator: the power level of the signal
generator is lowered from a higher than -85dBm level in 1 to 2 dB steps until the PER < 1% is no longer
measured at the receiver. This is the point of sensitivity.To clarify, the PER should be much lower than 1%
at higher input power levels to the receiver. As the power level drops, the PER will rise and eventually
equal or exceed 1% (the 802.15.4 Standard level). This then is the sensitivity of the device.
2.4.3
Energy Detect and Link Quality Indication (LQI)
The 802.15.4 receiver has the ability to measure the magnitude of the incoming signal energy (energy
detection or ED) to the receiver at its programmed frequency. The energy is measured and reported via one
of two mechanisms:
• Clear Channel Assessment (CCA) - the 802.15.4 PHY is based on a collision-avoidance protocol
where the channel is tested for interference before enabling a transmission. A CCA execution
enables the radio which does an energy detect on the channel and reports back to the higher layer
function (MAC). The CCA measures channel energy and compares to a preset threshold.
• Link Quality Indicator (LQI) - this is a measurement of the energy strength or quality of a received
packet. The LQI number is reported for each received packet. The 802.15.4 Standard requires that
the LQI be scaled and limited to have a range of decimal 0 to 255. Values of LQI above
approximately -30 to -25 dBm can be non-linear and should not be used as an indication of absolute
received power.
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RF Design Validation and Verification
NOTE
Refer Freescale’s 802.15.4 MAC PHY Software Reference Manual,
(802154MPSRM) to see how ED and LQI are reported in software.
The following quoted text is taken from the 802.15.4 Standard:
“The receiver energy detection (ED) measurement is intended for use by a network layer as part of a
channel selection algorithm. It is an estimate of the received signal power within the bandwidth of an IEEE
802.15.4 channel. No attempt is made to identify or decode signals on the channel. The energy detection
time shall be equal to 8 symbol periods.
The ED result shall be reported to the MLME using PLME-ED.confirm (6.2.2.4) as an 8-bit integer
ranging from 0x00 to 0xff. The minimum ED value (0) shall indicate received power less than 10 dB above
the specified receiver sensitivity (6.5.3.3 and 6.6.3.4), and the range of received power spanned by the ED
values shall be at least 40 dB. Within this range the mapping from the received power in dB to ED value
shall be linear with an accuracy of +/- 6 dB.”
The following quoted text is taken from reference P802.15.4/D18-6.7.8 of the 802.15.4 Standard:
(6.7.8) “The link quality indication (LQI) measurement is a characterization of the strength and/or quality
of a received packet. The measurement may be implemented using receiver energy detection, a
signal-to-noise ratio estimation, or a combination of these. The use of the LQI result by the network or
application layers is not specified in this standard.
The LQI measurement shall be performed for each received packet, and the result shall be reported to the
MAC sublayer using PD-DATA.indication (6.2.1.3) as an integer ranging from 0x00 to 0xff. The minimum
and maximum LQI values (0x00 and 0xff) should be associated with the lowest and highest quality IEEE
802.15.4 signals detectable by the receiver, and LQ values in between should be uniformly distributed
between these two limits. At least 8 unique values of LQ shall be used.”
To measure an LQI reported value:
• The signal generator sends a packet at a known power level on the receiver’s channel frequency.
• The DUT receives the packet and reports the measured LQI level.
• The reported energy value is compared against the set input power level
— The reported energy value should be within +/- 6dB of the actual input power level.
— The reported value format will be in compliance with 802.15.4 Standard requirements.
2.5
Recommended Software for Validation and Verification
Appendix A, “Freescale 802.15.4 RF Test Software” provides a listing and overview of available
Freescale applications suitable for RF validation and verification. Two basic appoaches to the evaluation
software may be taken:
• Simple suite of test functions - available for either HCS08 (SMAC) or the ARM7 (22xSMAC)
platforms, there are simple SMAC or 22xSMAC applications that provide basic RF test capability.
• Advantages of using these are:
— Source code is available
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— They are easily modified and less sophisticated
— Lend themselves to “quick startup”
— They can use a simple UART or switch based control interface
— More suitable for simple board-to-board and range testing
— They can easily be extended for FCC testing
Disadvantages include:
— Not as integrated approach as the following secondary approach
– More sophisticated, integrated test environment - also available for either HCS08 or the
ARM7, the “ZigBee Test Client (ZTC) and Test Tool” environment is a more complete and
capable test suite. The RF test capabilities are just a subset of the overall capability. If this
approach is used initially for evaluation, it may eliminate a second learning curve for use of
the software. One disadvantage can be that the more simple apps are more applicable for
quick startup and easy test modification.
Regardless of the software choice, all of the applications are designed for board-to-board use. The user
may be required to modify the applications to add control and synchronization to test equipment,
especially for PER testing.
2.6
Board-to-Board / Range Testing
After initial evaluation and verification, board-to-board and range testing are needed to determine actual
system performance. Board-to-board testing is the actual wireless, non-connected mode through the
antennas. Antenna type, performance, and matching into the RF feed connection impacts overall
end-to-end performance.
Once reasonable end-to-end performance is realized in the lab, range performance measurements can be
useful to better evaluate overall system capabilities. As previously stated in this manual, quantifying actual
RF power and receive sensitivity in a wireless environment can be very difficult, but comparative
performance is more easily done and can be sufficient.
2.6.1
Evaluating Board-to-Board Performance
Board-to-board or range performance is similar to connected performance in that a given board is either
receiving or transmitting. Performance in both modes must be evaluated in that receive sensitivity can be
poor while transmit performance is proper, and the inverse can also be true. For brand new application
boards that may not have been matched to the antenna, this is typically caused by different RF matching
performance while in one mode versus the other.
To evaluate over-the-air performance, PER testing is again used. The difference between direct connected
measurements and this over-the-air environment is that previously a generator provided the packet stream
for the sensitivity test and a spectrum analyzer measured the transmitter characteristics. Now, direct
board-to-board communication is used:
• For first evaluation of a new board, a known good reference module is recommended Development modules are available from Freescale, and other universal modules are commercially
available. The reference module can act as either the transmitter or receiver.
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2.6.2
Test software is a key component - Both sides of the RF link must have compatible test suites
running the PER test. Typically conditions are similar to the IEEE 802.15.4 Standard where the
PSDU size is 20 octets and the desired PER rate is 1% or less.
Using Freescale Software for Board-to-Board Testing
Board-to-board testing in the lab is the precursor to range testing (looking for the distance limit of the
module). The general procedure is:
1. Load compatible PER target software into a transmit module and a receive module — The transmit module can send a known number of packets of a known size
— The receive module reports number of packets received, the LQI level, and other attributes.
2. Run the PER test and establish basic operation in both the receive mode and the transmit mode — Initially in the lab, put the boards in close proximity to one another
— Board orientation can be important due to the directionality attribute of the antenna
— The PER test result should establish solid PER performance well below the 1% standard
— LQI results can give a general indication of received signal strength
NOTE
It is important to note that LQI is a highly variable measurement, and not
exact. The IEEE 802.15.4 Standard only requires that the measured LQI
accuracy be within +/-6 dB of actual. Secondly, many variables impact
received signal strength (antenna type, orientation, variation in TX output
power, distance variation between units) and contribute to LQI variation
Running the applications first on two known good modules and observing the results can provide
excellent background. These data can be used as a figure of merit for a similar target design.
3. If the PER testing does not give satisfactory results, the design must be debugged. Often for new
designs, the RF impedance matching to the antenna is the most common culprit. In general, if
receive performance is poor, then transmit performance will also be poor. However, this is not
always the case where one mode gives good performance and not the other. Customers who copy
the reference designs closely have been the most successful with first pass designs.
NOTE
Good practice is to assure that the PER TX application is supplying
expected power to the antenna. This requires making a connected TX power
measurement with the PER TX application. This is simply a double-check
before trying to address a potential hardware problem.
Freescale provides two useful applications for board-to-board PER testing, dependent on platform:
• PER Test RX / PER Test TX (SMAC for HCS08 platform) - These are the RX application and the
TX application for a basic packet error rate (PER) test. An individual test sends 1000 packets each
with a 20-byte payload on a single channel. Although there is a standalone mode, a PC may be used
for reporting test results. See Section A.2, “SMAC Test Applications for HCS08 Platform” for
more details.
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Connectivity Test (22xSMAC for ARM7 platform) - This application allows evaluation of the
basic connectivity with separate transmitter and receiver target modules. It supports PER test
measuring the percentage of packet losses over a certain channel. LQI of each received packet is
reported. Useful also for range test. A manual interface through push buttons or a menu driven
serial interface port (UART) is supported. See Section A.1.2, “PC Host Application for Test (Test
Tool)” for more details. Freescale highly recommends that customers load this software onto their
applications, if at all possible, to validate the functionality of their hardware before loading their
own application software.
2.6.3
Quantifying PER Test Results
Because there are so many variables regarding a wireless link, it is difficult to provide exact measurements
of radiated power and over-the-air receiver sensitivity. An expensive, highly calibrated RF test
environment is required, it is normally beyond the scope of a normal user, and fortunately really not
necessary. The approach in this discussion is essentially a “relative” performance test where the DUT is
compared against reasonable expected results.
Some contributing factors to RF link performance include:
• Transmitted power level - the actual transceiver output power may nominally be +/- 1 to 2 dB
higher or lower than the expected programmed level
• Antenna performance - the RF matching (receive and transmit) to the transceiver, antenna gain, and
radiation pattern affect radiated power and receive efficiency
• Signal propagation path - intervening obstacles such as walls, multi-path interference, and distance
between nodes.
• Interference of other propagating signals
• Background noise
• Receiver Sensitivity
Given the above listed factors in a lab situation, the dominant factors are typically going to be the distance
between the nodes (assuming little or no interference and an unobstructed signal path) and antenna effects.
2.6.3.1
Distance Between Nodes
The distance between nodes is typically the dominant source of reduced signal strength. Figure 2-4 shows
calculated received power (dBm) versus range (meters) using a typical 0 dBm transmit output power.
Observe that when power is measured in dB relative (as in dBc), it is a logarithmic scale versus the linear
scale for distance.
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Received Power vs Range
for 0 dBm Output Power, 0 dB gain Antennas
-50
-55
Received Power - dBm
-60
-65
-70
-75
-80
-85
-90
-95
-100
0
50
100
150
200
250
300
350
400
450
Range - meters
Figure 2-4. Graph of Received Power vs Range
The graph represents a somewhat theoretical best result. Given real losses in the path between the
transceiver transmitter and the receiver, real results would typically have greater signal loss.
When doing initial board-to-board testing, with very short distance between transmit and receive modules,
LQI may read as high as -60 dBm to -50dBm or higher. Again be reminded, LQI is not very exact and
signal strength can vary greatly at very close distance.
2.6.3.2
Antenna Effects
The transmitting antenna characteristics also impact the performance. Different types of antennae will
have different gain and different radiation patterns. One inherent problem with very small modules is that
as antenna physical size gets smaller it is less efficient.
A good low-cost solution to an 802.15.4 antenna has been a PCB F-antenna that has been a standard on
many Freescale designs. The radiation patterns of the F-antenna printed on the 13192-EVB module are
shown in Figure 2-5 and Figure 2-6.
• The radiation patterns are for the board orientations (top view) as shown to the right of the polar
graph.
• In Figure 2-5 the board is lying flat parallel to a horizontal surface (horizontal pattern)
• in Figure 2-6 the boards is lying on its long side (vertical pattern).
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The measurements were performed with the transceiver set to maximum output power, which
results in approximately +2dBm at the antenna plane of the board.
Figure 2-5. 13192-EVB Horizontal PCB Radiation Pattern
Figure 2-6. 13192-EVB Vertical PCB Radiation Pattern
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The radiation patterns show that the F-antenna has best signal strength to either side of the long axis of the
antenna. The signal is reduced when perpendicular to the long axis of the F-antenna.
2.6.4
Range Test
Once over-the-air operation of the module is generally validated in a lab situation, some applications may
desire evaluation of longer distance via a range test.
Over longer distances, the transmitted wave can produce reflection, diffraction, and/or scattering.
Reflection occurs when the transmitted wave encounters an object of large dimension as compared to its
wavelength. Common examples are buildings, large walls, and the ground. Some of the energy of the wave
may be transmitted or absorbed into the obstruction and the remaining energy will be reflected off of the
medium’s surface. The energy of the transmitted and reflected waves is a function of the geometry and
material properties of the obstruction and the amplitude, phase, and polarization of the incident wave.
Diffraction occurs when the surface of the obstruction has sharp edges producing secondary waves that in
effect bend around the obstruction. Like reflection, diffraction is affected by the physical properties of the
obstruction and the incident wave characteristics. In situations where the receiver is heavily obstructed,
the diffracted waves may have sufficient strength to produce a useful signal.
Scattering occurs when the transmitted wave encounters a large quantity of small dimension objects such
as lamp posts, bushes, and trees. The reflected energy in a scattering situation is spread in all directions.
These affect performance in addition to the other factors previously mentioned in Section 2.6.3,
“Quantifying PER Test Results”.
Although a variety of outdoor environments can be used, Line of Sight (LOS) on level terrain is best to
provide a basic understanding of the range performance. Other variables that impact range are:
• Antenna orientation (“standing” or “flat”)
• Output power level
• Receiver sensitivity
To implement a range test, it is suggested:
• Both transmitting and receiving boards be positioned about 1.2-2 meters above ground
• It is preferred that both units be connected to a portable laptop PC through a USB cable.
— Battery operation for the DUT modules is preferred
— The transmitter can sometimes be used without the PC through use of interface switches.
— Freescale test software (Section 2.6.2, “Using Freescale Software for Board-to-Board
Testing”) supports this operation
• Orient the DUT(s) for best antenna performance
• Increase distance until PER performance is unsatisfactory.
• Tests are typically run with nominal 0 dBm, max +2 dBm, and reduced -2 dBm TX power levels
Distances from 80 meters to 1000 meters may be seen depending on antenna type, antenna orientation, and
power out.
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Range results and path loss calculations are useful in determining link budgets. The link margin is defined
as the margin in dB above the receiver sensitivity level required to ensure reliable radio connection
between the transmitter and receiver. In optimum conditions (antennas are perfectly aligned, no multi-path
or reflections exists, and there are no losses) the necessary link margin would be 0dB. In real world
conditions, the link margins are typically in the range of 15 to 25dB.
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Chapter 3
FCC Pre-Certification/Certification
3.1
Introduction
The International Telecommunication Union (ITU), a branch of the United Nations, provides guidelines
for Radio Frequency (RF) spectrum allocations, but sovereign nations have the right to control radio
transmissions within their borders. Certification is the process of testing radio hardware to demonstrate
that it meets the stated regulations in the country in which it will operate. With respect to the IEEE 802.15.4
Standard, this discussion addresses intentional radiators, or RF Transmitters, operating in the 2400 MHz
“unlicensed” bands.
Generally, when electronic hardware is sold in a country, the certification requirements of that country
must be met. Usually only the initial certification is required unless changes are made to the hardware that
will affect the RF emission performance. As examples, IC changes and software revisions that do not
change radio performance are acceptable (see CFR 47 FCC Part 2.1043). Some countries, like Japan,
require filing notification with the regulatory agency even if engineering or demonstrations are performed
with RF emitting hardware.
For operation in the 2.4 GHz band (worldwide) the following standards apply:
• In the US, CFR 47 FCC, Part 15.203, 15.205, 15.209 and 15.247
• In Canada, RSS-210 (which closely follows FCC Part 15)
• In the EU, ETSI EN 300, 301
• In Japan, ARIB STD-T66
• Other countries generally follow FCC or ETSI
This chapter provides information and guidance on the pre-certification and certification process.
3.2
Planning for Certification
Start consideration of the certification process early in the design cycle:
• Work with an experienced certification lab to help determine which certification requirements
apply to the product
• Perform pre-certification testing or have the certification partner perform the tests to ensure
passing before finalizing the design and formally submitting for certification
3.2.1
Choosing the Correct Certification Lab is Important
Freescale recommends consulting an expert. Hire a respected test and certification lab that has experience
with unlicensed band hardware and can file (or help file) within the countries of interest.
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•
•
•
3.2.2
Costs will vary from as little as $10K to as much as $20K depending on how many certifications
are needed.
Make sure the certification lab can provide certification in the countries where it is required. Most
countries require local filing.
Select a house with demonstrated expertise in FCC Part 15 hardware certification. Freescale
partners include NTS and LS Research.
Include Certification Requirements/Activities in the Design Flow
To avoid issues later in the process, consider certification as part of the design and verification process.
• Select a certification lab BEFORE starting the design.
• Consult with them on critical issues, such as antennas, connectors and labeling. Labeling and
Documentation are the primary reason for failure of FCC audits.
• Work close with the lab partner during the design verification phase. Most Labs will gladly provide
pre-certification services and advice at a nominal fee.
• Do not wait until a short time before Product Launch to start the pre-certification activities. These
should be part of the design cycle. The testing and filing process takes time, in fact it can take as
long as 1-3 months.
• Filings must be accepted before the product is shipped
3.2.3
Alternatives
The certification process may present cost and resource barriers to some users. Commercial pre-certified
modules are an excellent alternative to OEM design for low volume applications or where RF hardware
expertise is lacking. Freescale has module partners. FCC and other regulatory agencies allow for
“modular” certification where the OEM can use a certified module and does not have to re-certify.
NOTE
An exception is if the radio transmitters are within 20 cm of each other, the
hardware must be re-certified.
3.2.4
Suggested Reading / References
Some suggested sources of additional information:
• CFR 47 FCC Part 15 – available from the FCC web site. Sections 35, 205, 209, 247
• FCC Publication 558074 – gives details on measuring digital radios; available from the FCC web
site (use Google search)
• “Simplifying FCC Compliance for 802.15.4 2.4 GHz Devices” – White paper by Glen Moore,
Wireless/EMC Manager, National Technical Systems
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3.3
Pre-Certification Testing
Basic RF test and verification have already been detailed. Once the design is working, there are some basic
measurements that should be made prior to Certification Testing. Consider these two options:
• Work with the Certification Lab on the first hardware design and have them assist as to how to
make these measurements
• Considering the complexity of the measurements, contract a Certification Lab to perform these
tests
•
•
NOTE
FCC Publication 558074 provides more details on measuring digital
radios
These tests may measure a similar parameter by different means than
described in Chapter 2, “RF Design Validation and Verification”.
Tests are performed in Continuous Modulation transmission mode (not packet) or PRBS9 random data
packet mode
A summary of pre-certification tests includes:
• Peak Output Power - conducted and radiated
• Spurious Emissions - conducted
• Spurious Emissions - radiated
• Duty Cycle Correction Factor
• Power Spectral Density (NOT as defined in IEEE 802.15.4 Standard)
NOTE
The listed pre-certification tests do not cover all the required certification
tests, but rather focus on the RF attributes that are impacted by the customer
board design. Since the tests are more easily done in conducted mode and
conducted mode gives more consistent results, Freescale recommends
performing all of the pre-certification tests in this mode and doing an
approximate mathematical conversion to determine specification
compliance.
Freescale provides applications for these tests, and continuous transmit modes are available in Freescale
SMAC test software (Test Mode application and Connectivity Test). The transmit mode suitable to a
related test is as follows:
• Duty Cycle Correction Factor measurement uses PRBS9 mode
• Power Spectral Density measurement uses PRBS9 mode
• Spurious measurements uses Continuous Modulated mode
• Peak Power measurements uses Continuous Modulated mode
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3.3.1
Measurement Equipment
The instrument list for the transmitter tests is shown in Table 3-1. In addition, other equipment such as
amplifiers, attenuators, filters, etc. are needed.
Table 3-1. Equipment Required for Transmitter Tests
Test Parameter
3.3.2
Spectrum Analyzer
6dB Bandwidth
1
Occupied Bandwidth
1
Peak Power
1
Power Spectral Density
1
Duty Cycle Correction Factor
1
Conducted Spurious Emissions
1
Conducted Spurious Emissions Band Edge
1
Radiated Spurious Emissions
1
Equivalent Isotrophic Radiated Power
1
Maximum E.I.R.P. Spectral Power Density
1
Frequency Range
1
Transmitter Spurious Emissions
1
Receiver Spurious Emissions
1
Vector Signal Analyzer
Peak Output Power
Peak output power is the maximum TX power at which the unit will operate. FCC Part 15.247 (b) (3)
applies:
• Sets a limit of 30 dBm
• This limit applies to conducted or radiated measurements. See FCC regulations for more detail
regarding radiated requirements
• Making the test as an RF conducted test is the easiest method to verify. Most applications operate
at a level that is far less power than the FCC limit.. Use a direct connection between the antenna
port of the transmitter and the spectrum analyzer, through suitable attenuation
• Sets the spectrum analyzer resolution bandwidth (RBW) greater than 6 dB bandwidth of the
emission, or use a peak power meter
3.3.2.1
•
•
•
•
Test Conditions
10 MHz RBW and video bandwidth VBW
Peak Detector
Max hold
NOT a band power measurement
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•
Test at low (band edge), mid and high (band edge) channels, i.e., frequencies 2405, 2445, and 2480
MHz
Use continuous modulated transmit mode (not packet)
Use a spectrum analyzer and perform the following tasks:
1. Set the SA center frequency to test frequency.
2. Set the power to max power.
3. Set the Resolution Bandwidth to 10 MHz.
4. Set the Video Bandwidth to 10 MHz.
5. Set the Span to 20 MHz.
6. Set the sweep time to auto.
7. Set the Spectrum Analyzer Detector mode to Peak Detector.
8. Set the Normal Marker to the peak magnitude.
9. Record the Peak Power.
10. Repeat listed steps for all remaining frequencies.
Figure 3-1. Peak Output Power
3.3.3
Spurious Emissions - Conducted (basic)
Spurious emissions are the unwanted transmit spectrum including harmonics, spurs and spectral mask. The
FCC Part 15.247 (d) applies:
• Sets a limit of -20 dBc for peak power or -30 dBc for average power within a 100 kHz bandwidth
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NOTE
RMS average power has a very specific definition as used in the FCC
document. Be cautious when applying this method.
•
•
Sets the test as an RF conducted and radiated tests. This section applies to conducted test.
Sets the spectrum analyzer resolution bandwidth (RBW) to 100kHz
The FCC also requires a conducted spurious emissions test more specific to the band edges (see
Section 3.3.4, “Conducted Spurious Emissions Band Edge”).
3.3.3.1
•
•
•
•
•
Test Conditions
100 kHz RBW, 300 kHz VBW
Peak Detector
Auto Sweep with Max Hold
Test each test frequency with Full spectrum sweep and band edge for each useable power level at
low, mid, and high-band transmission frequencies, i.e., 2405 MHz, 2445 MHz, and 2480 MHz.
Use continuous modulated transmit mode (not packet)
Use a spectrum analyzer and perform the following tasks:
1. Set the DUT Low frequency to be tested.
2. Set the DUT power to desired power.
3. Set the SA Start Frequency to 30 MHz.
4. Set the Stop Frequency to 26 GHz (or SA maximum frequency if less than 26 GHz).
5. Set the Resolution Bandwidth to 100 KHz.
6. Set the Video Bandwidth to 300 KHz.
7. Set the sweep time to 52 s.
8. Set the detection mode to Peak.
9. Must meet 20 dBc Peak or 30 dBc Average (See FCC document for definition of average.)
10. Repeat for each remaining frequency and power that the device will be operated.
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Figure 3-2. Conducted Spurious Emissions (basic)
3.3.4
Conducted Spurious Emissions Band Edge
The conducted spurious emissions band edge tests are in addition to the basic spurious emissions test. The
conducted spurious emissions are determined for low-band and high-band transmission frequencies, i.e.,
2405 MHz, and 2480 MHz. On either side of the 802.15.4 band are forbidden bands. Therefore, this close
look is necessary for compliance assurance. When using an external PA, the highest useable transmission
frequency is 2475 MHz.
Use a spectrum analyzer and perform the following tasks:
1. Set the DUT Low frequency to be tested.
2. Set the DUT power to desired test power.
3. Set the SA Center Frequency to 2400 MHz.
4. Set Span to 20 MHz or wider if necessary to capture possible spurious peaks.
5. Set Resolution Bandwidth to 100 KHz.
6. Set Video Bandwidth to 300 KHz.
7. Set sweep time to 5 ms.
8. Set detection mode to Peak.
9. Set display to Max Hold.
10. Locate highest in-band peak and highest peak below 2400 MHz - must meet 20 dBc Peak or 30
dBc Average.
11. Repeat for each remaining frequency and test power.
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Figure 3-3. Conducted Spurious Emissions Low-Band Edge
For high-band edge, repeat the above measurements with Center Frequency set to 2.4835 GHz for Step 3.
Look for highest peak above 2.4835 GHz in Step 10.
3.3.5
Spurious Emissions - Radiated (basic)
Spurious emissions tests done with the radiated RF signal are also required and are similar to conducted
tests, but are done in a 3-meter RF chamber. The FCC Part 15.247 (c) applies as well as Parts 15.209 and
15.205 because the ISM 2.4 GHz band has “forbidden bands” on either side of it (these bands include 2.2
- 2.3 GHz, 2.31 - 2.39 GHz, and 2.483 - 2.5 GHz). The set limit is 500µV/m (54 dBµV/m) for the average
detector.
Most users do not have the specialized equipment necessary to make radiated measurements, so conducted
measurements with antenna gain can be substituted for gauging FCC compliance. Table 3-2 shows the
signal power conversions necessary for using conducted tests.
The above limit of 500 uV/m @ 3 meters in FCC 15.209 is converted to dBuV/m as follows:
• 20 * log(500) = 53.98 dBuV/m
• The peak limit is 20 dB above 53.98 or 73.98 dBuV/m
Table 3-2. Power Conversions for Limits When Substituting Conducted Tests for Radiated Emissions
Average Limit
Frequency Range of
Converted from Field
Harmonic or Spurious
Strength to dBm
Emission
Measured @ RF Port
(MHz)
(dBm)
Above 960
-41.12
Average Field
Strength Limit of
Fundamental @ 3m
(dBµV/m)
54
Peak Limit Converted
Peak Field Strength
from Field Strength to
Limit of Fundamental
dBm measured @ RF
@ 3m
Port
(dBµV/m)
(dBm)
74
-21.2
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NOTE
Refer to the National Technical Systems “white paper” cited in
Section 3.2.4, “Suggested Reading / References” for more information.
A test method is presented here to achieve a level of confidence in equivalent radiated data from conducted
measurements.
3.3.5.1
•
•
•
•
•
Test Conditions
FCC Publication 558074 specifies Continuous Modulation mode, not packet mode
If the Average limit is applied, a Duty Cycle Correction Factor (DCCF) can be used per 15.35 (b):
— On-time / Off-time in 100 ms
— DCCF can only be applied to the fundamental related spurious and not random spurious.
— The IEEE 802.15.4 standard is a burst-mode, low duty cycle protocol with a relatively low raw
bit rate of 250 kbps. The DCCF can be generally estimated by use model; experience has shown
that an equivalent throughput of ~75 kbps (30% duty cycle) is a very high usage model, and in
contrast, the ZigBee Alliance specifies no more than 10% duty cycle. A reasonable
compromise is a common packet model: one full packet transmitted with no acknowledgement
received, then the packet is re-transmitted 3 more times with no acknowledgement, yielding a
17% duty cycle:
– Maximum 802.15.4 packet contains 133 bytes
– At 250 kbps data rate, bit time = 4 µs and byte time = 32 µs
– 133 byte packet lasts 4.26 ms.
– 4 transmitted packets is total on-time of 17 ms
Using averaging measurement
— 1 MHz RBW, 10 Hz VBW
— Auto Sweep with Max Hold
— Continuously modulated
— Apply duty cycle correction factor (DCCF)
Alternatively, Peak limits and conditions can be used. The Peak limit can be applied with no
correction factor.
— 1 MHz RBW, 1MHz VBW
— Auto Sweep with Max Hold
— Continuously modulated
— Do Not Apply duty cycle correction factor (DCCF)
The Spurious Emissions are determined for low-band and high-band transmission frequencies, i.e.,
2405 MHz, and 2480 MHz. When using an external PA, the highest useable transmission frequency
is 2475 MHz.
NOTE
Do not use dBµV mode on the spectrum analyzer; it does not correct for
radiated power.
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Use a spectrum analyzer and perform the following tasks:
• Follow the method as described in Section 3.3.3, “Spurious Emissions - Conducted (basic)” by
doing a general spur search, breaking up the span above and below the intentional radiator as
needed to detect spurs with the detector in peak mode above the desired frequency band. Set the
detector to quasi-peak CISPR for frequencies below 1GHz.
• The frequencies covered should go from below the band edge down to as close to DC as possible
and above the band edge to 26 GHz (or as high as your equipment will allow).
1. Set the DUT Low frequency to be tested.
2. Set the DUT power to desired test power.
3. Set Start Frequency to 30 MHz (The blocking caps in the SA does not allow it to be in calibration
below approximately 30 MHz).
4. Set Stop Frequency to 2.39 GHz.
5. Set Resolution Bandwidth to 1 MHz.
6. Set Video Bandwidth to 10 Hz (averaging measurements).
7. Set sweep time to 60 s.
8. Set detection mode to Peak.
9. Set display to Max Hold.
10. Locate highest peak and place a marker-normal.
11. Note Frequency and magnitude. Spurs must meet -21.2 dBm peak (VBW=1 MHz) and -41.2 dBm
average (VBW=10 Hz).
12. Repeat Steps 2 through 11 for High band frequencies and operating powers.
When performing the conducted tests for qualification of radiated results, the measurements need to be
converted to dBuV/m and compared to these limits. To convert conducted measurements into radiated @
3 meters:
• Subtract 95.2 from the measured conducted spur to obtain dBuV/m from dBm
• The RMS detector measurements (VBW= 10 Hz) are then reduced by the DCCF before being
compared to the 53.98 limit
• The peak detector measurements are compared to the 73.98 limit
• Note that the DCCF is not applied to the peak limit (VBW= 1 MHz)
NOTE
If pulsed measurements are the only method of measuring the signal, then
be sure to synchronize the SA to the output signal. Otherwise, the video
effects of how the SA interprets the signal will give false data which could
cause the part to seem to fail the limits. If the DUT cannot be put into
continuous mode, this fact needs to be communicated to your certification
vendor.
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Figure 3-4. Radiated Spurious Emissions (Measured Conducted - Video Average)
Figure 3-5. Radiated Spurious Emissions (Measured Conducted - Video Peak)
3.3.6
Radiated Spurious Emissions Band Edge
The radiated spurious emissions band edge tests are in addition to the basic radiated spurious emissions
test. Again, actual conducted tests are used to quantify the radiated performance.
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The conducted spurious band edge emissions are determined for low-band and high-band transmission
frequencies, i.e., 2405 MHz, and 2480 MHz. When using an external PA, the highest useable transmission
frequency is 2475 MHz.
Use a spectrum analyzer and perform the following tasks. Peak detection is found first, then the average
detection.
1. Set the DUT Low frequency to be tested.
2. Set the DUT power to desired power.
3. Set the Spectrum Analyzer Center Frequency to 2390 MHz.
4. Set Span to 40 MHz.
5. Set Resolution Bandwidth to 1 MHz.
6. Set Video Bandwidth to 1 MHz.
7. Set sweep time to 5 ms.
8. Set detection mode to Peak.
9. Set display to Max Hold.
10. Locate highest peak below 2390 MHz - Must meet 73.98 dBuV/m Peak.
11. Repeat for each remaining frequency.
12. For average detection, repeat above steps Step 1 - Step5, then make the following SA settings
changes, and finally measurement Step 10:
— Step 6. Set Video Bandwidth to 10 Hz
— Step 7. Set sweep time to 10 s
NOTE
The equipment may be unable to achieve the combination of 10 s sweep and
10 Hz VBW. Freescale recommends that the span be adjusted to
accommodate the VBW as necessary.
— Step 8. Set display to Clear Write
— Step 10. Locate highest peak below 2390 MHz - must meet 73.98 dBuV/m Peak (VBW= 1
MHz) and 53.98 dBuV/m Average (VBW= 10 Hz)
For high-band edge, repeat above measurements with Center Frequency set to 2.4835 GHz for Step 3.
Look for highest peak above 2.4835 GHz in Step 10.
The limit of 500 uV/m at 3 meters in FCC 15.209 is converted to dBuV/m as follows:
20 * log(500)=53.98 dBuV/m. The peak limit is 20 dB above 53.98 or 73.98 dBuV/m.
The above measurements need to be converted to dBuV/m and compared to these limits.
To convert conducted measurements into radiated at 3 meters, subtract 95.2 from the measured conducted
spur to obtain dBuV/m from dBm. The RMS detector measurements are then reduced by the DCCF before
being compared to the 53.98 limit. The peak detector measurements are compared to the 73.98 limit. Note
that the DCCF is not applied to the peak limit. Also, do not apply the DCCF to spurious that is not related
to the fundamental.
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3.3.7
Duty Cycle Correction Factor
If used, the FCC certification process requires that the stated DCCF for the module be demonstrated. The
duty cycle of the transmitter is observed with a 100ms window.
3.3.7.1
•
•
•
•
Test Conditions
PBRS9 transmit mode is used with your application duty cycle
Use SA in zero span
Measure on-time versus off-time in 100 ms
Use mid-band frequency (2445 MHz)
Use a spectrum analyzer and perform the following tasks
1. Set the DUT center frequency to be tested.
2. Set the DUT power to max power.
3. Set the SA SPAN to ZERO SPAN.
4. Set Resolution Bandwidth to 10 MHz.
5. Set Video Bandwidth to 10 MHz.
6. Set Span to 20 MHz.
7. Set the SA sweep time to 5 ms.
Figure 3-6. On Time for a Single Pulse
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Figure 3-7. Number of Pulses During 100ms Duty Cycle
In this case, the ON-Time is 2.417 mS. Since there are 9 pulses in 100 mS, the duty cycle is (9*2.417)/100.
The Duty Cycle Correction Factor (DCCF) is then 20 Log (Duty Cycle)= 10 Log (.2175) = -6.62 dB. This
means that the radiated average data can be de-rated by 6.62 dB before being compared to the FCC
requirement.
3.3.8
Power Spectral Density (PSD)
Power Spectral Density may also be observed as part of pre-certification, but is not necessarily required
as it is determined by modem’s transmitter. FCC Part 15.247 (d) applies:
• Sets a limit of 8 dBm / 3 kHz
• Sets the test as an RF conducted test
3.3.8.1
•
•
•
•
•
•
•
Test Conditions
3 kHz RBW and VBW > RBW
Peak Detector
Max hold
Sweep = 500 seconds (Span/3 kHz)
Span = 1.5 MHz
Test at low (band edge), mid and high (band edge) channels, i.e., frequencies 2405, 2445, and 2480
MHz
MUST use PRBS9 transmit mode
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NOTE
This measurement is strictly a conducted value as the FCC specifies the
power spectral density delivered to the antenna.
Using a spectrum analyzer (SA), a suggested procedure is:
1. Set the SA center frequency to the desired frequency to be tested
2. Set the DUT power to max power
3. Set the Resolution Bandwidth to 3 KHz
4. Set the Video Bandwidth to 10 KHz
5. Set the Span to 1.5 MHz
6. Set the sweep time to 500 s
7. Set the detector mode to Peak Detector
8. Set the Normal Marker to the peak magnitude
9. Record the Peak Power - compare against the 8 dBm max requirement.
10. Repeat steps listed above for remaining frequencies
Figure 3-8. Power Spectral Density
3.4
Getting Certification
This set of tests are inclusive but not comprehensive of those required to pass FCC certification. Once
product development and pre-certification testing is complete, the actual certification is done in
partnership with the Test and Certification Lab. If an early relationship has been developed, this process
should go smoothly. The certification testing will require certain deliverables by the assembly vendor, and
these may include:
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•
•
•
•
Specific target hardware ready for conducted tests
Specific target hardware ready for radiated tests.
Special applications or utilities for testing
— Test suites to facilitate certification tests
— End-to-end application(s) for interference tests
Supporting documentation (IC data sheets, schematics, bill of materials, etc.)
The test lab will be able to give guidance on the required support package for a particular certification.
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Chapter 4
Production Test Guidelines
4.1
Introduction
This chapter describes manufacturing test recommendations for products that employ Freescale IEEE®
802.15.4 Standard wireless technology. This information is intended for test, system, and product
engineers responsible for developing and maintaining production test systems for these products. It is
recommended that they are familiar with the IEEE 802.15.4 Standard and its associated terminology, and
also have a basic working knowledge of board test techniques.
•
•
4.2
NOTE
This chapter is not intended as a full test suite guide and assumes the
user is familiar with manufacturing test methodologies. This chapter
provides guidance to specific requirements that may be unique or useful
to the Freescale IEEE 802.15.4 devices and applications.
A number of vendors supply commercial test tools and equipment
specifically targeted for IEEE 802.15.4 / ZigBee applications. The user
is encouraged to investigate these solutions as they may provide
significant benefits.
Production Test Characteristics
The board or module that is the Device Under Test (DUT) will already have been evaluated and validated
by earlier design and test stages. As a result, the production test stage of the development cycle focuses on
reducing test time and lowering manufacturing costs per unit while still validating that the units leaving
the production line are properly assembled and functional. The production test process must encompass
the following elements:
• Repeatability
• Stability
• Robustness
• Reliability
• Cost Effectiveness
Consider several important test steps on the manufacturing floor when dealing with IEEE 802.1.5.4
Standard chipsets:
• Programming an application image
— A test application image into MCU RAM or non-volatile memory (NVM)
— Final target application NVM image
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•
•
•
•
•
4.3
Communication interface
RF Tests
Crystal Test and Calibration
MAC Address Handling
Software Tools
Freescale Tools to Support Production Test
In the following descriptions, it is stated that a test application can run on the target MCU to assist in
production test. Freescale provides test software tools/utilities and a number of application notes that can
assist developing tools for production test applications.
• See Appendix A, “Freescale 802.15.4 RF Test Software” for a listing of software utilities and
associated application notes. The primary software utilities useful to production testing are The ZigBee Test Client (ZTC) — This is a MAC based application.
Connectivity Test — This is a SMAC based application.
• AN3860 - MC1322x Flash Loader Utility (Second Stage Loader)
4.4
Programming a Test Application or NVM Image
The Freescale portfolio of parts for the IEEE 802.15.4 Standard includes 8-bit (HCS08) and 32-bit (ARM7
based) MCUs and several different memory configurations. This requires numerous options for
programming the DUT in the production line. Also, two different types of images may be required to be
loaded:
Test application image To functionally validate the transceiver/radio and any peripheral functions, an
application can be loaded that enables/performs prescribed tests. Depending on
the target device, the test application can reside in RAM or in NVM (FLASH
memory).
Final target application The end application binary image must be loaded into the MCU NVM. This can
happen as part of the final production test flow or it can be pre-loaded prior to
board assembly using commercial solutions
Depending on production volume, it is usually more convenient to have the ICs programmed prior to the
assembly process.
For low to medium volume programming, tools are available from various Freescale tool vendors for
on-board programming. For the 8-bit products, P&E Micro offers the Cyclone Pro USB Multilink©
interface. For the 32-bit products, IAR offers software to work with the J-Link© ARM Processor
programmer. For high volume programming, tooling is available for all products from System General and
programming services are available from Source Electronics, which is now part of Avnet.
4.4.1
HCS08 Platforms
All the HCS08 MCUs feature in-circuit debug and FLASH programming tools available via the on-chip
background debug module (BDM) and its serial debug port. Although this is the common, primary means
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of downloading a target application image, there is also the option of using a serial UART port in
conjunction with a test application. These are described as follows:
• BDM debug serial port — Access to the BDM port is most commonly supplied via a standardized 2x3 6-pin header
compatible with the P&E Micro (www.pemicro.com) USB CYCLONE PRO tool for HCS08.
– The MCU BKGD and RESET lines must be available for this connection
– Alternatively, access to this port has been provided via PCB pads for a bed-of-nails
connection. These test signals can be routed to the BDM tool.
— If the HCS08 FLASH has been pre-programmed with the target application in NVM, a test
application would normally execute from RAM. This limits the test application binary size to
the RAM size which is typically from 4 kbytes to 8 kbytes.
NOTE
The target application can include a means to load and the run test code in
RAM or the BDM can be used to load the test code (although this must be
done carefully)
•
4.4.2
— Commercial solutions, such as those provided by P&E Micro can be employed to program the
HCS08 based MCU in the production line.
Test application and communication port - Freescale provides a MAC-based application called Test
Tool. Test Tool consists of a target MCU client application and a personal computer (PC)
Command Console application to communicate with and control the MCU client application
through a UART port. The Test Tool client can be loaded via the BDM port, and then run as a test
application.
— For production test purposes, the Command Console application must be replaced by a test
interface such as a NI LabVIEW™ application.
— Test Tool PC application supports loading of a FLASH application image through the BDM.
ARM7 Platforms
The ARM7 solutions from Freescale are different from the HCS08 platforms in that an application
program executes from ROM/RAM as opposed to executing directly from FLASH as on the HCS08
platforms. In normal operation, the boot process for these devices executes from ROM, transfers a binary
image from serial FLASH to RAM and then transfers execute to RAM. This provides a different model
than the HCS08 for loading a program image and for loading test code. Two different programming
options for the ARM7 platform include the serial debug interface and alternative boot load approach:
• Serial debug port
— The ARM7 debug serial interface is via a standardized JTAG debug port - this port is used for
in-circuit debug and serial FLASH and/or RAM programming. Access to the JTAG port is most
commonly supplied via a standardized 2x10 20-pin header compatible with the IAR Systems
(www.iar.com) J-Link USB-JTAG Debugger for ARM.
– The MCU TDI, TMS, TCK, RTCK, TDO and RESET lines must be available
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•
•
– Alternatively, access to this port can be provided via PCB pads for a bed-of-nails
connection. These test signals are then routed to the J-Link tool.
— A test application can be loaded and executed from RAM, and the test application binary size
can be as large as 80 kbytes.
— Commercial solutions, such as those provided by IAR, can be employed to program the serial
FLASH in the production line.
Similar to the HCS08 scenario, the Freescale Test Tool MCU client can be loaded into RAM of the
ARM7 platform. The client has a NVM load utility.
Boot load option - The ARM7 platform boot process involves first executing from ROM and
normally loading the RAM from a valid serial FLASH image. If no valid FLASH image is present,
the alternate boot flow can used to load an executable.
NOTE
• If the ARM7-based device has had a valid application image loaded into
the serial NVM prior to board assembly, the boot load option for
production is not possible. The standard JTAG debug port tools must be
used.
• Although the alternate boot load option is briefly described here, the
user is directed to the MC1322x Reference Manual (MC1322xRM),
Chapter 3 and Appendix C for complete information on the device
bootloader
— Lacking a valid NVM image, the ARM7 boot flow looks for an alternate source of executable
code from a prioritized set of serial interface ports. The user can enable UART1 (most
common), the SPI port, or the I2C bus as the boot load port
– For the selected port, the corresponding interface signals must be available with no conflict
with external peripherals
– The selected option must be enabled as described in the MC1322x Reference Manual,
(bootstrap flow)
– The communication protocol and data formatting are described in the MC1322x Reference
Manual
— Freescale provides software utilities to help implement this process
– The Test Tool suite is available in the Freescale BeeKit Wireless Connectivity Toolkit.
– Application note AN3860, MC1322x Flash Loader Utility (Second Stage Loader) is also
useful
4.4.3
Updating or Reloading of NVM Image
Although not necessarily part of the production test flow, the need for updating/reloading a valid
application image in NVM may be required after production or in the field.
• Providing a PCB onboard connector for the device serial debug port as a standard feature is good
practice. This enables use of the debugger hardware in the field for both debug and updating the
NVM image.
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•
•
4.5
The RF communication capability of these modules provides a unique potential option of
over-the-air programming (OTAP) to update the NVM image. This is costly in that an external
serial NVM must be present to store the new image as it is received by the target node for later self
update. Freescale provides sample applications that demonstrate this function.
Described in Section 4.4.2, “ARM7 Platforms”, the boot load option can be also used for field
update of these platforms. One caution is that the present valid NVM image must first be erased
before the boot load function can be used, and hardware means can be provided to facilitate
self-erase of the NVM image. See the MC1322x Reference Manual.
Communication Between Tester Platform and DUT
The primary communication channel between the tester and the DUT is normally the MCU serial debug
port. The appropriate debugger tool connects to the DUT, and in turn, communicates back to a personal
computer (PC) typically through a USB port. Debug/Test/NVM utility software runs on the PC and
supports the test environment.
It is also common practice to take advantage of the onboard MCU to test the radio and any utilized
peripherals. The test application can run out of RAM and can be downloaded through the serial debug port.
A disadvantage after the test application is downloaded and running is that communication through the
debugger can be fairly slow and can lengthen test time.
A good option is to dedicate a serial port such as a UART to tester communication.
• Communication rate will be much faster than using the serial debugger
• The target test application must support the communication interface
• The communication interface signals must be available to the tester as a connector or as pads on
the PCB
• A commons means is to use a DUT UART
— Provide an off-board UART<>USB interface, and the PC can support the USB connection as
a Virtual Comm Port (VCP)
— This channel can also be used for the ARM7 platform boot load interface if desired.
• This can provide a direct control channel for sending commands to the target test application
4.6
Crystal Testing and Calibration
In many other MCU applications it is sufficient to know that a crystal frequency source is running, and the
actual frequency error (as determined by the crystal and its loading) is not critical. However, as described
earlier, the IEEE 802.15.4 Standard requires that the frequencies and symbol rates associated with the radio
transmit and receive functions have an accuracy of +/-40 ppm or better.
• With properly specified crystals, Freescale devices can maintain a typical accuracy of +/-30ppm or
better over temperature and voltage variation.
• The recommended crystal specifications list a maximum frequency cut of ± 10 ppm at 25 °C
• It is recommended that the DUT frequency error be tested and assured that it is ± 10 ppm or less;
if not, individual unit tuning may be required. The Freescale IEEE 802.15.4 ICs can all trim the
crystal reference oscillator frequency through programming of onboard trim load capacitance.
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4.6.1
HCS08 Platforms
The MC1320x and MC1321x devices have a 16 MHz reference oscillator that is part of the transceiver IC
and are trimmed by writing to a SPI register on the transceiver. All Freescale software for these devices is
based on the HCS08 platform. Guidelines for measuring the error frequency include:
• Monitor the reference frequency at output pin CLKO
— Do not load the crystal oscillator pins directly because this causes a frequency shift.
— The CLKO signal must be available for test
• Use an accurate frequency counter (resolution of 1-2ppm) such as an Agilent 53131A
• A test application running on the target MCU should support changing the trim setting in the proper
transceiver SPI register (Register 0A Bits 15-8 xtal_trim [7:0]) - the production test equipment
should include an automatic routine to trim the frequency in the production line based on the
frequency counter reading. A good target at room temp is > ± 10 ppm.
• The custom trim value is retained to be inserted into the target MCU application code image.
A custom oscillator trim value can be one of multiple custom parameters that need programmed into the
DUT NVM. See Section 4.8.1, “HCS08 Parameters” for a description of programming techniques.
NOTE
For HCS08 FSL MAC-based applications, the crystal trim parameter is
Abel_HF_Calibration. See Section 4.8.1, “HCS08 Parameters” for a
description of programming techniques..
4.6.2
ARM7 Platforms
The MC1322x devices have a single IC for the radio/MCU combination and the 24 MHz (typical)
reference oscillator is onboard and trimmed by writing a register in the MCU register address map.
Guidelines for measuring the error frequency include:
• The MC1322x devices do not have a clock-out pin, a timer module (TMR) must be programmed
as a divider and the resulting frequency out monitored at the TMRx’s associated at output pin
TMRx. Similar to the HCS08 guidelines — Do not load the crystal oscillator pins directly because this causes a frequency shift.
— The TMRx signal must be available for test
• Use an accurate frequency counter (resolution of 1-2ppm) such as an Agilent 53131A
• A test application running on the target MCU should support changing the trim setting in the proper
control register (XTAL_CNTL Bits 25-16, {XTAL_CTUNE[4:0],XTAL_FTUNE[4:0]}) - the
production test equipment should include an automatic routine to trim the frequency in the
production line based on the frequency counter reading. A good target at room temp is > ± 10 ppm.
• The custom trim value is retained to be inserted into the target MCU application code image.
A custom oscillator trim value can be one of multiple custom parameters that need programmed into the
DUT NVM. See Section 4.8.2, “ARM7 (MC1322x) Parameters” for a description of programming
techniques.
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NOTE
For ARM7 MAC-based applications, the crystal trim parameters are
gXtalCTune_c and gXtalFTune_c. See Section 4.8.2, “ARM7 (MC1322x)
Parameters”.
4.7
RF Tests
As already stated, the main goal of production test is to validate that the DUT is assembled correctly and
is functional. Production test is not intended to validate that the board fulfills the complete IEEE 802.1.5.4
Standard requirements. Though the production tests are similar to those used when certifying an IEEE
802.15.4 Standard design, these tests are minimized to shorten overall testing time. The goal of production
test is to exercise the IEEE 802.15.4 PHY layer (or radio) to validate the RF front end of the module.
To reduce testing time, not all 802.15.4 channels need to be tested. Testing just one, two, or three channels
should be enough. This also holds true for power levels.
NOTE
In recommending reduced RF production testing, Freescale assumes a
complete assessment and validation of the RF front end components and
design of the module has been accomplished, and the design has been fully
qualified.
4.7.1
Recommended Production RF Tests
For validation of the module assembly, the recommended RF tests are limited to:
• Relative TX output power
• Relative Receiver input sensitivity
• Packet Error Rate (PER)
In these tests note that relative TX power and RX sensitivity are stated. This is because accurate, absolute
power out and sensitivity measurements are very difficult without direct connection of the test instrument
to the DUT, and most modules do not have easy means for direct connection. Making radiated
measurements (although less accurate) are much easier and sufficient for the purpose of establishing
correct, functional assembly.
4.7.2
RF Test Means and Environment
Radiated signal strength between units is determinate on many factors including transmitted output power,
antenna type and orientation, distance between units, etc. As a result, the suggested means to establish
relative test limits is to use known good units (commonly called GOLDEN units) or use test instruments
with known parameters. For a test signal source, a known good “golden” module unit can be used or a
properly programmed vector signal generator tied to an antenna, and the signal generator must be capable
of sending proper IEEE 802.15.4 packets to establish both PER and receiver sensitivity. To measure DUT
transmit power, a golden unit or a spectrum analyzer with connected antenna can be used.
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A mechanical fixture to hold the DUT in a repeatable, known position and orientation is required. Once
this test fixture is established, it can be calibrated for relative RF performance against known units or
standards. Possible means of DUT-to-test unit communication can include:
• Golden unit to DUT - the golden unit can be located in close proximity to the DUT fixture (perhaps
antenna-to-antenna), and the configuration calibrated through known good characterized units.
• RF test pad (plus test instrument) to DUT - Flat type antenna couplers mounted on a test pad are
available. A custom mechanical mounting on the pad for the DUT can be added to provide
repeatable measurements. The antenna coupler is connected via cable to proper test
instrumentation. TESCOM Co., Ltd. (http://www.tescom.co.kr) is one supplier of these and other
RF test accessories.
• Antenna (plus test instrument) to DUT - A good antenna connected to the test instrumentation can
be mounted in close proximity to the DUT. Again a good mechanical mounting for the DUT is
required to provide repeatable measurements
On the manufacturing floor, the DUT can share the electromagnetic spectrum with other RF DUTs or test
instrumentation. External sources of interference can be present, such as base stations, adjacent test
systems, microwaves, phone systems, etc. These potential interferers must be taken into account because
they can affect test effectiveness and consequently test results.
To sufficiently suppress these signals, use a custom or commercial shielded RF test chamber with at least
60 dB shielding isolation over the 2.4 GHz ISM bandwidth. One such commercial chamber is the R&S
TS712X shielded RF test chamber. (http://www2.rohde-schwarz.com)
4.7.3
Test Instrumentation
The following table shows some recommended test instruments for testing the IEEE 802.15.4 PHY and
MAC layer.
Table 4-1. Instruments Recommended for RF Test
Manufacturer
4.8
Test Instrument
Comments
Agilent Technologies
N4010A, 89600 VSA, MXA,
For testing PHY layer
National Instruments
5663 VSA, 5673VSG
For testing PHY and MAC layers
Rohde & Schwarz
FSU, FSQ , SMU,
For testing PHY layer
Tektronix
RTSA
For testing PHY Layer
Production Data and MAC Address Handling
Typically, every manufactured unit must have some unique parameters or identifiers stored for operation
and/or traceablility. These parameters can include:
• Manufacturing date and site
• IC device version
• Software version
• Operational/radio settings
802.15.4/ZigBee RF Evaluation and Test Reference Manual, Rev. 1.0
4-8
Freescale Semiconductor
Production Test Guidelines
•
IEEE 802.15.4 MAC address - all IEEE 802.15.4 Standard devices must have a unique MAC
address that individually identifies the device in the network.
Freescale’s MAC and MAC-based solutions (RF4CE, SynkroRF, MAC, BeeStack) have been designed to
support these unique parameters. Contained within the MAC is a “PRODUCTION DATA TABLE” that
resides at a fixed NVM address range (each platform uses a different address range). This table allows for
the production test flow to modify the target application binary for each unique unit. Two general means
are used to customize the table:
• Directly modify the target download application binary - if the DUT NVM has not been previously
loaded with the target application binary, it must be loaded into the DUT as part of the test flow
(usually a final step). The application binary can be modified immediately preceding this step and
then the customization is included as part of the normal download process.
• Directly load the production data table (or some of its elements) into NVM after test - if a “generic”
DUT application binary has been previously loaded into the NVM either before assembly or is
loaded as part of the test flow, the customized NVM location unique to each device must be left
unprogrammed. The test application running on the MCU can then load a table into NVM or just
those elements unique to a given DUT.
The table location NVM address and means to load the table are different based on the target platform. The
following sections describe the process for the HCS08 and ARM7 platforms.
•
•
4.8.1
NOTE
These descriptions are limited to the Freescale 802.15.4 MAC and
MAC-based stacks. Other Freescale software offerings such as the
SMAC and 22x-SMAC did not support these structures and providing
equivalent functionality is left as an exercise for the user.
The user is advised to always check the latest revision of
software/database for changes to production table location and/or
parameters. These may be subject to change.
HCS08 Parameters
For the HCS08-based platforms (GT60, MC1321x, QE128 MCU, etc.):
• The production data table is called FREESCALE_PROD_FLASH and resides at NVM address
range 0xFF50 to 0xFFAF.
— This declaration is found in the PLM\PRM\Linker.prm linker file of the Codewarrior project
— The linker file also directs that the FREESCALE_PROD_DATA (the production parameters)
be loaded into the FREESCALE_PROD_FLASH area
• The C code data structures used to define version strings and hardware parameters are found in the
PLM\Interface\NV_Data.h file
— They are used to declare the FREESCALE_PROD _DATA segment; also in the NV_Data.h file.
— Observe use of a 5-byte “Delim” ASCII string at the beginning and end of the parameters table
to delimit the table and allow an application to find the table contents if it moves address
— The data structures are as follows:
802.15.4/ZigBee RF Evaluation and Test Reference Manual, Rev. 1.0
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4-9
Production Test Guidelines
*****************************************************************************/
/* The Freescale version string struct is placed at a specific location in */
/* ROM by the linker command file, and is normally only written during */
/* manufacturing. */
typedef struct FreescaleVersionStrings_tag {
uint16_t NV_RAM_Version;
uint8_t MAC_Version[4];
uint8_t PHY_Version[4];
uint8_t STACK_Version[4];
uint8_t APP_Version[4];
uint8_t HWName_Revision[4];
uint8_t SerialNumber[4];
uint16_t ProductionSite;
uint8_t CountryCode;
uint8_t ProductionWeekCode;
uint8_t ProductionYearCode;
uint8_t MCU_Manufacture;
uint8_t MCU_Version;
uint8_t NOT_USED;
} FreescaleVersionStrings_t;
/* The HardwareParameters_t struct is treated specially by both the */
/* linker command file and the startup (crt0.c) code. See the comments */
/* in crt0.c. */
/* The initialString and terminalString are unsigned chars, instead of */
/* uint8_t, because the C standard guarantees the sizeof(unsigned char). */
/* These strings are needed by the startup code to locate the current */
/* copy of the structure in NV storage, if there is one, and must be the */
/* first and last fields in the type. */
#define gaHardwareParametersDelimiterString_c
"Delim"
typedef struct HardwareParameters_tag {
unsigned char initialString[ sizeof( gaHardwareParametersDelimiterString_c )];
uint8_t Bus_Frequency_In_MHz;
uint16_t Abel_;
uint16_t Abel_HF_Calibration;
#ifdef PROCESSOR_QE128
uint8_t NV_ICSC1;
uint8_t NV_ICSC2;
uint8_t NV_ICSTRM;
uint8_t NV_ICSSC;
#else
uint8_t NV_ICGC1;
uint8_t NV_ICGC2;
uint8_t NV_ICGFLTU;
uint8_t NV_ICGFLTL;
#endif
uint8_t MAC_Address[8];
uint8_t defaultPowerLevel;
uint8_t useDualAntenna;
uint8_t paPowerLevelLimits[16];
unsigned char terminalString[ sizeof( gaHardwareParametersDelimiterString_c )];
} HardwareParameters_t;
/*****************************************************************************
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Freescale Semiconductor
Production Test Guidelines
•
Table 4-2 provides a list of the version string and hardware parameters and their suggested usage.
A number of parameters are recommended as Freesacle reserved, meaning they will be set via the
software tools. Others are available to the user — The user version parameters may be established at the application build/compile time and may
not need to be set by the actual test flow
— The Abel_HF_Calibration parameter is the 8-bit oscillator trim value that gets loaded into the
transceiver register
— The MAC_Address[8] parameter is the 8-byte MAC address used by the MAC function
Table 4-2. HCS08 Version String and Hardware Parameters Listing
Version/Parameter Name
No of Bytes
Suggested Usage
NV_RAM_Version
2
FSL Reserved
MAC_Version[4]
4
FSL Reserved
PHY_Version[4]
4
FSL Reserved
STACK_Version[4]
4
FSL Reserved
APP_Version[4]
4
User optional
HWName_Revision[4]
4
User optional
SerialNumber[4]
4
User optional
ProductionSite
2
User optional
CountryCode
1
User optional
ProductionWeekCode
1
User optional
ProductionYearCode
1
User optional
MCU_Manufacture
1
FSL Reserved
MCU_Version
1
FSL Reserved
NOT_USED
1
User optional
Bus_Frequency_In_MHz
1
FSL Reserved
Abel_Clock_Out_Setting
2
FSL Reserved
Abel_HF_Calibration
1
User optional / oscillator trim
NV_ICSC1 / NV_ICGC1
1
FSL Reserved
NV_ICSC2 / NV_ICGC2
1
FSL Reserved
NV_ICSTRM / NV_ICGFLTU
1
FSL Reserved
NV_ICSSC / NV_ICGFLTL
1
FSL Reserved
MAC_Address[8]
8
User optional
defaultPowerLevel
1
FSL Reserved
useDualAntenna
1
FSL Reserved
paPowerLevelLimits[16]
16
FSL Reserved
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Production Test Guidelines
•
•
The FREESCALE_PROD_DATA table (or segment) values are normally assigned/defined in the
PLM\Source\Common\Sys\NV_Data.c file. Any custom user parameters that are not DUT
dependent can be pre-assigned.
DUT-dependent FREESCALE_PROD_DATA table parameters (typically a custom trim
Abel_HF_Calibration and MAC_Address) can be loaded into the target NVM by the test flow in a
number of ways:
— Modify the target S-record (application.s19) file before the application gets loaded to the
DUT - the s19 file can be loaded via the BDM debug tool or other applications
— Define the custom parameter NVM byte locations as 0xFF (unprogrammed NVM state) in the
source, so that if the application image is preloaded to the NVM these bytes can be
programmed later via a test utility program - the user must be sure to know the actual physical
address(es) of the parameters to be written later
— Load the parameters as a block after the target application image has been loaded - use a utility
running in RAM to write the parameters as a block.
Freescale's Test Tool can assist in validating that the information was stored correctly. Use the firmware
loader for the HCS08 and load the NVM Information. The file generated from this application contains the
NVM production data section of the .S19 file. The following figure shows the NVM parameters window
in Test Tool.
Figure 4-1. Test Tool NVM-Parameters Window
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Production Test Guidelines
4.8.2
ARM7 (MC1322x) Parameters
For the ARM7-based platforms (MC1322x):
• The production data table is called “nv_data_init_struct” and resides at serial NVM address range
0x00400800 to 0x004008FF.
— This declaration is found in the PLM\Icf\MC1322x-RAM-ROM.icf linker file of the IAR tools
project
— The linker file also directs that the “nv_data_init_struct” (the production parameters) be loaded
into the “INIT_region” which is also defined as the address range of 0x00400800 to
0x004008FF in the linker file.
• The C code data structures used to define version strings and hardware parameters are found in the
PLM\Interface\NV_Data.h file
— They are used to declare the nv_data_init_struct segment; defined in the
PLM\Source\Common\Sys\NV_Data.c file.
— Observe use of a 5-byte “Delim” ASCII string at the beginning and end of the parameters table
to delimit the table and allow an application to find the table contents if it moves address
— The data structures are as follows:
*****************************************************************************/
/* The Fresscale version string struct is placed at a specific location in */
/* ROM by the linker command file, and is normally only written during */
/* manufacturing. */
typedef struct FreescaleVersionStrings_tag {
uint16_t NV_RAM_Version;
uint8_t MAC_Version[4];
uint8_t PHY_Version[4];
uint8_t STACK_Version[4];
uint8_t APP_Version[4];
uint8_t HWName_Revision[4];
uint8_t SerialNumber[4];
uint16_t ProductionSite;
uint8_t CountryCode;
uint8_t ProductionWeekCode;
uint8_t ProductionYearCode;
uint8_t MCU_Manufacture;
uint8_t MCU_Version;
uint8_t NOT_USED;
} FreescaleVersionStrings_t;
/* The HardwareParameters_t struct is treated specially by both the */
/* linker command file and the startup (crt0.c) code. See the comments */
/* in crt0.c. */
/* The initialString and terminalString are unsigned chars, instead of */
/* uint8_t, because the C standard guarantees the sizeof(unsigned char). */
/* These strings are needed by the startup code to locate the current */
/* copy of the structure in NV storage, if there is one, and must be the */
/* first and last fields in the type. */
#define gaHardwareParametersDelimiterString_c
"Delim"
typedef struct HardwareParameters_tag {
unsigned char initialString[ sizeof( gaHardwareParametersDelimiterString_c )];
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Production Test Guidelines
uint8_t Bus_Frequency_In_MHz;
uint8_t MAC_Address[8];
uint8_t defaultPowerLevel;
uint8_t dualPortRFOperation;
uint8_t paPowerLevelLimits[16];
uint8_t ccaThreshold;
bool_t
enableComplementatyPAOutput;
bool_t
gSystemClock24MHz_c;
uint8_t gXtalCTune_c;
uint8_t gXtalFTune_c;
uint8_t gDigitalClock_PN_c;
uint8_t gDigitalClock_RN_c;
uint16_t gMACA_Clock_DIV_c;
uint32_t gDigitalClock_RAFC_c;
uint8_t gaRFSynVCODivI_c[16];
uint32_t gaRFSynVCODivF_c[16];
uint8_t paPowerLevelLock;
unsigned char terminalString[ sizeof( gaHardwareParametersDelimiterString_c )];
} HardwareParameters_t;
/*****************************************************************************
•
Table 4-3 provides a list of the version string and hardware parameters and their suggested usage.
A number of parameters are recommended as Freesacle reserved, meaning they will be set via the
software tools. Others are available to the user — The user version parameters may be established at the application build/compile time and may
not need to be set by the actual test flow
— The gXtalCTune_c and the gXtalFTune_c parameters are the coarse and fine oscillator trim
values that get loaded into the XTAL_CNTL register
— The MAC_Address[8] parameter is the 8-byte MAC address used by the MAC function
Table 4-3. ARM7 Version String and Hardware Parameters Listing
Version/Parameter Name
No of Bytes
Suggested Usage
NV_RAM_Version
2
FSL Reserved
MAC_Version[4]
4
FSL Reserved
PHY_Version[4]
4
FSL Reserved
STACK_Version[4]
4
FSL Reserved
APP_Version[4]
4
User optional
HWName_Revision[4]
4
User optional
SerialNumber[4]
4
User optional
ProductionSite
2
User optional
CountryCode
1
User optional
ProductionWeekCode
1
User optional
ProductionYearCode
1
User optional
MCU_Manufacture
1
FSL Reserved
802.15.4/ZigBee RF Evaluation and Test Reference Manual, Rev. 1.0
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Production Test Guidelines
Table 4-3. ARM7 Version String and Hardware Parameters Listing
Version/Parameter Name
No of Bytes
MCU_Version
1
FSL Reserved
NOT_USED
1
User optional
Bus_Frequency_In_MHz
1
FSL Reserved
MAC_Address[8]
8
User optional
defaultPowerLevel
1
FSL Reserved
dualPortRFOperation
1
FSL Reserved
paPowerLevelLimits[16]
1
FSL Reserved
ccaThreshold
1
FSL Reserved
enableComplementatyPAOutput
1
FSL Reserved
gSystemClock24MHz_c
•
•
Suggested Usage
FSL Reserved
gXtalCTune_c
1
User optional / oscillator coarse tune
gXtalFTune_c
1
User optional / oscillator fine tune
gDigitalClock_PN_c
1
FSL Reserved
gDigitalClock_RN_c
1
FSL Reserved
gMACA_Clock_DIV_c
2
FSL Reserved
gDigitalClock_RAFC_c
4
FSL Reserved
gaRFSynVCODivI_c[16]
16
FSL Reserved
gaRFSynVCODivF_c[16]
16
FSL Reserved
gaRFSynVCODivF_c[16]
16
FSL Reserved
The nv_data_init_struct table (or segment) values are normally assigned/defined in the
PLM\Source\Common\Sys\NV_Data.c file. Any custom user parameters that are not DUT
dependent can be pre-assigned.
DUT-dependent nv_data_init_struct table parameters (typically custom oscillator trim and
MAC_Address) can be loaded into the target NVM by the test flow in a number of ways:
— Modify the target binary file before the application gets loaded to the DUT - the file can be
loaded via the JTAG debug tool or other applications
— Define the custom parameter NVM byte locations as 0xFF (unprogrammed NVM state) in the
source, so that if the application image is preloaded to the NVM these bytes can be
programmed later via a test utility program - the user must be sure to know the actual physical
address(es) of the parameters to be written later
— Load the parameters as a block after the target application image has been loaded - use a utility
running in RAM to write the parameters as a block.
For the MC1322X, Freescale's Test Tool can assist in validating that the MAC address information was
stored correctly. Use the firmware loader for the MC1322x. Once the bin file is selected, the MAC address
802.15.4/ZigBee RF Evaluation and Test Reference Manual, Rev. 1.0
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4-15
Production Test Guidelines
section displays the current DUTs MAC Address. Test Tool is not intended to be used for mass production
but only as a diagnostic and repair tool.
4.9
Simple Overview of Test Flow
Each situation will be different based on the application, but Table 4-4 provides a simple overview of a
typical test flow.
Table 4-4. Simple Test Flow
Feature
Component
Power supply
Test
Test Preconditions
Input Stimulation
Expected Result
Comments
Voltage
• Check main Module DC voltages.
• Use DMM to measure voltage across
different TP’s
Voltages are within specs.
Current
• Check main Module DC Currents.
• The insertion of current breakthroughs
and dedicated voltage networks to the
IC, eases testing.
Currents are within specs.
Program Testing
image
• Using serial debug port, program test
firmware to NVM or RAM as
appropriate to exercise all the
peripherals in use by the applications
software
Testing successful. Include a
register-based flag to indicate the testing
was successful.
Note: The testing required for MCU
peripherals and asociated external
circuitry is totally dependent on the
user application.
Reference Oscillator Trim
Crystal Trim
• PTEQ Firmware outputs the defined
“Crystal Frequency” or a multiple of it
through a GPIO or a defined test pin
• Use Frequency Counter to measure
frequency
• If FMHz_in > Crystal Frequency ±
10ppm
• Then adjust XTAL trim values until
• FMHz_in < Crystal_Frequency ± 10ppm
• Store XTAL_TRIM
FMHz_in<= Crystal_ frequency ± 10ppm.
Save XTAL_TRIM
RF RX
• Using PTEQ Firmware set the DUT in
the receiver mode.
PERCH [email protected] < 1%
• Set the DUT to perform a PER.
PERCH [email protected] < 1%
• Set the VSG to send 1000 packages,
20 kbytes payload.
PERCH [email protected] < 1%
• Relative Pout to set actual received
power to about -90dBm
• Perform the PER on desired Channels
Programming test
software
RF Receiver
Tests
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Production Test Guidelines
Table 4-4. Simple Test Flow
Feature
Component
Test
RF Transmitter
Tests
Test Preconditions
Input Stimulation
Expected Result
Comments
• Using PTEQ Firmware set the DUT in
the transmitter mode.
• Set the DUT in continuous
unmodulated wave
• Nominal Power
• Using the VSA
• Measure Output power
VSA_UNCH 20 = 0 dBm
• Set the DUT to send PER packetts
• Measure PER < 1% at test instrument
PER CH A < 1%
Programmed successfully
Programming
FLASH Final
Application with
MAC Address
Using serial debug port, program FLASH
Final Application.
Additional program NVM device
dependent parameters as required
Print Label
Label with
Factory defined
values
For every DUT that passes all the previous Print Label
functional tests, a Label containing the
MAC address, the crystal trim and the
serial number
802.15.4/ZigBee RF Evaluation and Test Reference Manual, Rev. 1.0
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802.15.4/ZigBee RF Evaluation and Test Reference Manual, Rev. 1.0
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Freescale Semiconductor
Appendix A
Freescale 802.15.4 RF Test Software
A.1
Test Applications and Tools Overview
The RF test software ranges from simple standalone applications running on the target board to more
capable and sophisticated tools that use a client application running on the target board with host
application running on a personal computer (PC).
A.1.1
Target Applications for RF Test
Table A-1 lists the software target applications recommended for test or modification for test. These are
applications that run on the platform MCU on the target board.
NOTE
These applications all assume use of Freescale’s Beekit Wireless
Connectivity Toolkit software tools.
Table A-1. Freescale 802.15.4 Recommended Software Apps for RF Test
Description
Platform
Documentation
Test Mode
application
SMAC application that allows PHY level testing
on all channels through button presses. Includes
PBRS9, RX, TX with Modulation, CW.
HCS08
AN3231
Hardware evaluation,
FCC pre-cert
Basic Packet
Error Test
SMAC application that send 1000 packets of 20
byte payload. Operates with USB PC connection
or with button presses.
HCS08
AN3231
Engineering or
production Range
testing
Range
Demonstration
Plus
SMAC application that provides LED indication of
LQI
HCS08
AN3231
Range testing
ZigBee Test Client MAC and BeeStack application that supports the
(ZTC)
features of Test Tool. Can be used with a
customer host via UART.
HCS08,
ARM7
Application
Connectivity Test
SMAC application that allows Radio Testing,
reference oscillator frequency measurement and
adjustment, PER and LQI vs range
measurement. Interface is selectable between
button pushes or UART.
ARM7
Suitable for
ZigBee Test Client Hardware evaluation,
Reference Manual FCC pre-cert, starting
(ZTCRM)
point for production test
firmware
MC1322x SMAC ARM7 hardware
Demonstation
evaluation and FCC
Application User testing
Guide
(22xSMACDAUG)
MC1322x Reference Manual, Rev. 1.0
Freescale Semiconductor
A-1
Freescale 802.15.4 RF Test Software
A.1.2
PC Host Application for Test (Test Tool)
Test Tool is a Freescale provided Windows® based graphical interface utility that communicates with
802.15.4 target development and applications boards. Test Tool provides the following features:
• Command Console — Allows users to send and receive commands from a PC to a Freescale
802.15.4 development board through a virtual COM port (VCP)
• Script Server — Allows users to load, execute, and review results of Python Scripts and Test Sets.
• HCS08 Firmware Loader — Allows users to flash different application code into Freescale HCS08
based development boards from Test Tool using a USB multilink device (BDM)
• MC1322x Firmware Loader - Allows users to load application code into either RAM or flash
memory of MC1322x ARM7 based development boards, using a USB or serial cable connected to
the board’s communication port
• Radio Test — Allows users to run various radio tests employing just one board for various radio
tests or Packet Error Rate (PER) tests employing two boards. The Radio Test mode adjusts to the
board type under test (HCS08 or MC1322x ARM7)
Test Tool must be used with an appropriate client application on the target/development board. In the list
of applications from Table A-1, ZigBee Test Client (ZTC) is the proper client. Radio test capability is a
subset of the full functionality of this client application.
A.2
SMAC Test Applications for HCS08 Platform
Use of the Freescale Beekit applications is based on the different codebases. The “HCS08 SMAC
Codebase x.x.x” for the HCS08 platform is a Freescale proprietary protocol meant for simple applications
and supports several simple test applications:
• Test Mode - This application is a simple tool for testing basic RF transmitter performance.
Operation of the application is controlled by push button switches to select radio channel
(frequency) and TX mode. The supported modes are:
— Idle - no TX output; radio not active
— TX 9th Order Binary Polynomial (PRBS9) - TX output is continuous stream of packet with
PRBS9 random data
— RX_ON - no TX output; radio in RX mode
— TX_ON with modulation - TX output is continuous carrier with modulation
— TX_ON Continuous Wave (CW) without modulation - TX output is continuous carrier with no
modulation
• PER Test RX / PER Test TX - These apps are the RX application and the TX application for a
basic packet error rate (PER) test. The TX application is loaded into the transmitting node and the
RX application is loaded into the receiving node. An individual test sends 1000 packets each with
a 20-byte payload on a single channel. Although there is a standalone mode, a PC may be used for
reporting test results. Supported features are:
— Communication with a PC through a USB virtual Com Port (VCM)
— Control by 2 switches to change channel and start test
— Four Channels or frequencies used; 2405 GHz, 2430 GHz, 2455 GHz, and 2480 GHz
MC1322x Reference Manual, Rev. 1.0
A-2
Freescale Semiconductor
Freescale 802.15.4 RF Test Software
•
— PC COM port reports: 1) number of packets received, 2) Length of packet, 3) link quality
(LQI), cyclical redundancy check (CRC), and load data
Range Demo Plus - This application is constructed of two binary images that get loaded on two
separate boards:
— The TX range demo plus application (TX_APP)
— The RX range demo plus (RX_APP)
The TX_APP repeatedly transmits packets (with ACK enabled) at a given rate. The RX_APP
receives a given packet and responds with an “ACK” frame. The ACK differs based on the strength
of the received TX packet as measured by the TX packet LQI. For field testing, LEDs on both
boards are flashed in a manner to indicate both successful transmission and relative signal strength.
In the field, the user can then change the distance between boards to get a measure of usable range.
A.3
22xSMAC Test Application for ARM7 Platform (Connectivity Test)
Connectivity Test is based on the 22xSMAC codebase for the ARM7 platform. This application allows
evaluation of the basic connectivity between two transceivers. Separate transmitter and receiver target
modules with suitable applications are required. The connectivity test supports the following functionality:
• Configure the transceiver in a specific test mode in order to test the transmitter RF performance available test modes are:
— Modulated transmission
— Unmodulated transmission
— Pulse PRBS9 transmission (TX 9th Order Binary Polynomial)
— Idle (no TX output)
• Packet Error Rate (PER) test - measures the percentage of packet losses over a certain channel.
Also reports the Link Quality Indicator (LQI) of each packet received.
• Range test - reports the Link Quality Indicator of a signal; can be used as a range test.
• Other parameters, such as the channel and power can be modified to allow testing on channels with
different power values.
• Reference oscillator trim - a programmed timer output pin is provided to measure reference
oscillator frequency accuracy (ppm) and to trim the frequency as necessary.
Two possible interfaces are implemented; a manual interface through push buttons or a serial interface port
(UART) that is menu driven. Only one interface can be selected at a time (the interface type is selected
when creating the project within BeeKit).
Connectivity Test is a useful application for simple development and first evaluation of RF characteristics
of a new target design/layout. It is also easily modified or expanded by the user to add tests.
MC1322x Reference Manual, Rev. 1.0
Freescale Semiconductor
A-3
Freescale 802.15.4 RF Test Software
A.4
ZigBee Test Client (ZTC)
The Freescale ZigBee Test Client (ZTC) diagnostic tool is primarily intended for extensive testing of the
BeeStack protocol layer interfaces. Used with the Freescale Test Tool PC software, through the ZTC client
application a user can start/implement a network, and run any of the over 300 commands to test the
BeeStack application services and interfaces. Part of this capability is an RF test suite called “Radio Test”
that is an integral function within Test Tool. The capabilities of radio test are similar to other applications:
• Radio test including transmitter
• Packet error rate
• Setting board parameters including trimming the reference oscillator
• Reading/writing device registers
ZTC and Test Tool together provide a more capable and sophisticated environment that the other discussed
applications. This environment can be extended for FCC certification and for module production testing.
MC1322x Reference Manual, Rev. 1.0
A-4
Freescale Semiconductor
Appendix B
RF Test Modes in The MC1320x and MC1321x Transceivers
B.1
Introduction
The Freescale MC1320x family and MC1321x family 802.15.4 transceivers support certain RF test modes.
Although Freescale provides software applications that enable RF test modes, it is the intent of this
appendix to provide background information on hold to enable these RF test modes.
B.2
SPI Registers That Support RF Test
The 20x and 21x transceivers share the same SPI register model. Table B-1 list registers that impact RF
test and reference oscillator trim.
11
Control_B
07
tmr_load
ct_bias_en
ct_bias_inv
RF_switch_mode
miso_hiz_en
PA_Enable
08
CLKO_Ctl
0A
BER_Enable
30
PSM_Mode
31
10
9
8
7
6
5
4
3
2
1
0
Default
doze_en
12
hib_en
13
use_strm_mode
14
rx_done_mask
15
tx_done_mask
Add
(Hex)
clko_doze_en
REGISTER
NAME
pa_en
Table B-1. Modem SPI Register Table
0x0C00
0xFFF7
clko_rate[2:0]
ber_en
xtal_trim[7:0]
0x7E86
0x0004
psm_tm[2:0]
0xA000
The Control_B Register 0x07 controls the RF mode of operation, i.e., single port vs dual port and use of
the CT_Bias pin. Also, the 16MHz crystal trim field is found in the CLKO_Ctl Register 0x0A. These
registers, however, are typically not affected by RF testing.
Table B-2 lists the bit fields useful for controlling the transceiver for RF tests.
MC1322x Reference Manual, Rev. 1.0
Freescale Semiconductor
B-1
RF Test Modes in The MC1320x and MC1321x Transceivers
Table B-2. Transceiver SPI Register Fields Useful for RF Test
Field
Register Bit(s) Default
Description
pa_en
0x08
15
0b1
Power amp (PA) enable - when pa_en = 1, the TX PA is enabled. When pa_en =
0, the transmitter puts out no power.
ber_en
0x30
15
0b0
Bit error rate test enable - when ber_en = 1, the transceiver is put in continuous
receive or transmit mode. Continuous TX mode is useful for current measurements
or for looking at the TX spectrum. Continuous RX mode is useful for current
measurements.
psm_tm[2:0]
0x31
5-3
0b000
B.3
Phase shift modulator test mode - only two modes are used for this field. When
psm_tm[2:0] = 0b000, this is normal operation (normal modulation). When
psm_tm[2:0] = 0b001, the modulator is disabled and the transmitter puts out an
unmodulated signal.
Programming the Transceiver for Test Modes
The MC13202 and MC1321x transceivers are capable of two data transfer modes: (Packet Mode and
Streaming Mode). The MC13201 transceiver supports only Packet Mode. The Packet Mode is often used
to implement the RF test modes. The RF modes are activated by setting appropriate control bits and then
invoking RX or TX packet data mode.
B.3.1
Transmitter Test Modes
There are several transmitter modes that are useful for testing RF output spectrum.
B.3.1.1
Continuously Transmit Unmodulated Carrier
It is possible to transmit a continuous, unmodulated signal. This mode is useful for observing transmitter
center frequency and measuring TX current for the transceiver. Packet transmit mode is used. The steps to
implement this mode include first sending a dummy packet to setup the TX analog circuitry, next disabling
the modulator, and then turning on continuous transmit mode:
• Setup TX analog circuitry by sending a dummy packet
— Disable the PA (write pa_en, Register 0x08, Bit 15 = 0).
— Set the message field length to a short number (frame length of 4 is a good example).
— Transmit dummy message (PA is off) to setup TX analog circuitry (use packet mode and no
data needs to be loaded because dummy data is sufficient).
— Wait for transmission completion (this can be interrupt driven by waiting for tx_done IRQ).
• Enable the PA (write pa_en, Register 0x08, Bit 15 = 1).
• Enable the continuous TX mode (write ber_en, Register 0x30, Bit 15 = 1).
• Disable the phase shift modulator (write psm_tm[2:0], Register 0x31, Bits 5-3 = 0b001).
• Enable the transmitter with a TX operation which will be continuous and without modulation
(RXTXEN must be high and set xcvr_seq[1:0] to TX mode).
The TX operation will continue until aborted.
MC1322x Reference Manual, Rev. 1.0
B-2
Freescale Semiconductor
RF Test Modes in The MC1320x and MC1321x Transceivers
B.3.1.2
Continuously Transmit Modulated Carrier
It is possible to transmit a continuous, modulated signal. Packet transmit mode is used. The data pattern
sent is a repeating sequence of the two (2) symbols stored in tx_pkt_ram[15:0], Register 0x02. The steps
to implement this mode include first sending a dummy packet to setup the TX analog circuitry and then
turning on continuous transmit mode:
• Setup TX analog circuitry by sending a dummy packet
— Disable the PA (write pa_en, Register 0x08, Bit 15 = 0).
— Set the message field length to a short number (frame length of 4 is a good example).
— Transmit dummy message (PA is off) to setup TX analog circuitry (use packet mode and no
data needs to be loaded because dummy data is sufficient).
— Wait for transmission completion (this can be interrupt driven by waiting for tx_done IRQ).
• Load desired 2 TX symbols into tx_pkt_ram[15:0] (these 2 symbols will get continuously
repeated).
• Enable the PA (write pa_en, Register 0x08, Bit 15 = 1).
• Enable the continuous TX mode (write ber_en, Register 0x30, Bit 15 = 1).
• Enable the transmitter with a TX operation which will be continuous and with modulation as
determined by the data word (RXTXEN must be high and set xcvr_seq[1:0] to TX mode).
The TX operation will continue until aborted.
B.3.1.3
Transmit PRBS9 Data Packet Data
It is useful to repeatedly transmit a known data packet for observing transmitter characteristics as part of
radio certification. The packet uses pseudo-random binary sequence (PRBS) data generated via a maximal
length 9th order binary polynomial (PRBS9). The packet length is set to the maximum length of 127 bytes
(including the two CRC data bytes).
When using packet transmit mode, the following steps assume default operation of the transceiver (PA
enabled, ber_en off, and modulator enabled) and include:
• Generate 125-byte data buffer based on a PRBS9 algorithm (such as x9 + x5 +1 polynomial).
• Load data buffer into tx_packet_ram[15:0].
• Set message field length to 127 (maximum length).
• Enable the transmitter with a TX operation which will be normal with modulation (RXTXEN must
be high and set xcvr_seq[1:0] to TX mode).
• Wait for transmission completion (this can be interrupt driven by waiting for tx_done IRQ).
• To repeat the transmission, again enable the transmitter with a TX operation.
PBRS9 can also be sent via the streaming data packet mode (with the same message parameters) as would
be used with the 802.15.4 MAC services.
MC1322x Reference Manual, Rev. 1.0
Freescale Semiconductor
B-3
RF Test Modes in The MC1320x and MC1321x Transceivers
B.3.2
Receiver Test Mode
Other than normal operation, there is one additional receive test mode that is useful. A continuous receive
mode can be enabled that turns on the analog receive circuitry and leaves it on. This is useful for measuring
current in RF receive mode.
The steps include enabling a receive with the ber_en bit set:
• Enable the continuous RX mode (write ber_en, Register 0x30, Bit 15 = 1).
• Enable the receiver with a RX operation which will be continuous (RXTXEN must be high and set
xcvr_seq[1:0] to RX mode).
Packet error rate (PER) is used to measure normal receiver operation. A true bit error rate is not possible
for the receiver because no direct access to the decoded bit stream is given.
MC1322x Reference Manual, Rev. 1.0
B-4
Freescale Semiconductor
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