Embedded &

Industrial Computing

Hardware Platforms for Embedded and Industrial Computing

LEC-7230-CT1

V1.0

User's Manual

Release date: 2016/11/28

Overview

Icon Descriptions

The icons are used in the manual to serve as an indication of interest topics or important messages.

Below is a description of these icons:

NOTE:

This check mark indicates that there is a note of interest and is something that you should pay special attention to while using the product.

WARNING:

This exclamation point indicates that there is a caution or warning and it is something that could damage your property or product.

Online Resources

The listed websites are links to the on-line product information and technical support.

Resource

Lanner

Website

http://www.lannerinc.com

RMA http://eRMA.lannerinc.com

Copyright and Trademarks

This document is copyrighted, © 2014. All rights are reserved. The original manufacturer reserves the right to make improvements to the products described in this manual at any time without notice.

No part of this manual may be reproduced, copied, translated or transmitted in any form or by any means without the prior written permission of the original manufacturer. Information provided in this manual is intended to be accurate and reliable. However, the original manufacturer assumes no responsibility for its use, nor for any infringements upon the rights of third parties that may result from such use.

Acknowledgement

Intel, Pentium and Celeron are registered trademarks of

Intel Corp.

Microsoft Windows and MS-DOS are registered trademarks of Microsoft Corp.

All other product names or trademarks are properties of their respective owners.

Compliances and Certification

CE Certification

This product has passed the CE test for environmental specifications. Test conditions for passing included the equipment being operated within an industrial enclosure. In order to protect the product from being damaged by ESD (Electrostatic Discharge) and EMI leakage, we strongly recommend the use of CEcompliant industrial enclosure products.

FCC Class A Certification

This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment. This equipment generates, uses and can radiate radio frequency energy and, if not installed and used in accordance with the instruction manual, may cause harmful interference to radio communications. Operation of this equipment in a residential area is likely to cause harmful interference in which case the user will be required to correct the interference at his own expense.

Revision History

Version Date

1.0

Revision

2014/12/30 Official release

EMC Notice

This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to Part

15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment.

This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instruction manual, may cause harmful interference to radio communications. Operation of this equipment in a residential area is likely to cause harmful interference in which case users will be required to correct the interference at their own expense.

Safety Guidelines

Follow these guidelines to ensure general safety:

• Keep the chassis area clear and dust-free before, during and after installation.

• Do not wear loose clothing or jewelry that could get caught in the chassis. Fasten your tie or scarf and roll up your sleeves.

• Wear safety glasses/goggles if you are working under any conditions that might be hazardous to your eyes.

• Do not perform any action that creates a potential hazard to people or makes the equipment unsafe.

• Disconnect all power by turning off the power and unplugging the power cord before installing or removing a chassis or working near power supplies

• Do not work alone if potentially hazardous conditions exist.

• Never assume that power is disconnected from a circuit; always check the circuit.

LITHIUM BATTERY CAUTION:

Risk of explosion could occur if battery is replaced by an incorrect type. Please dispose of used batteries according to the recycling instructions of your country.

• Installation only by a trained electrician or only by an electrically trained person who knows all the applied or related installation and device specifications..

• Do not carry the handle of power supplies when moving to other place.

• The machine can only be used in a fixed location such as labs or computer facilities.

Operating Safety

• Electrical equipment generates heat. Ambient air temperature may not be adequate to cool equipment to acceptable operating temperatures without adequate circulation. Be sure that the room in which you choose to operate your system has adequate air circulation.

• Ensure that the chassis cover is secure. The chassis design allows cooling air to circulate effectively. An open chassis permits air leaks, which may interrupt and redirect the flow of cooling air from internal components.

Electrostatic discharge (ESD) can damage equipment and impair electrical circuitry. ESD damage occurs when electronic components are improperly handled and can result in complete or intermittent failures. Be sure to follow ESD-prevention procedures when removing and replacing components to avoid these problems.

• Wear an ESD-preventive wrist strap, ensuring that it makes good skin contact. If no wrist strap is available, ground yourself by touching the metal part of the chassis.

• Periodically check the resistance value of the antistatic strap, which should be between 1 and 10 megohms

(Mohms).

Rack Mounting Installation Environment Precaution

1. Elevated Operating Ambient - If installed in a closed or multi-unit rack assembly, the operating ambient temperature of the rack environment may be greater than room ambient. Therefore, consideration should be given to installing the equipment in an environment compatible with the maximum ambient temperature (Tma) specified by the manufacturer.

2. Reduced Air Flow - Installation of the equipment in a rack should be such that the amount of air flow required for safe operation of the equipment is not compromised.

Mechanical Loading - Mounting of the equipment in the rack should be such that a hazardous condition is not created due to uneven mechanical loading.

3. Mechanical Loading - Mounting of the equipment in the rack should be such that a hazardous condition is not achieved due to uneven mechanical loading.

4. Circuit Overloading - Consideration should be given to the connection of the equipment to the supply circuit and the effect that overloading of the circuits might have on over-current protection and supply wiring. Appropriate consideration of equipment nameplate ratings should be used when addressing this concern.

5. Reliable Earthing - Reliable earthing of rack-mounted equipment should be maintained. Particular attention should be given to supply connections other than direct connections to the branch circuit (e.g. use of power strips).”

Chapter 1: Introduction 5

System Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Package Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Standard Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Optional Power Cords. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Optional Mounting Kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Optional Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Chapter 2: System Components 7

System Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Front Components. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Rear Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Chapter 3: Board Layout 11

External Connectors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Internal Connectors and Jumpers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

Add-on Card. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Connectors and Jumpers List. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

Jumper and Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

Chapter 4: Hardware Setup 18

Preparing the Hardware Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

Installing the System Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

Installing the Wireless Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

Installing the 3G SIM Card . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

Installing the Hard Disk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

Appendix A: Programming Watchdog Timer 20

Chapter 1:

Introduction

Thank you for choosing Lanner LEC-7230-CT1. The

LEC-7230-CT1 is a fanless and robust embedded box

PC system utilizing the Intell® Bay Trail CPU J1900 with improved graphical and media performance, including supports for USB 3.0, low-powered DDR3L and VGA/

HDMI display. The system is ideal for efficient imaging workflows, digital signage with secure content delivery, visual appealing interactive clients (interactive kiosks, intelligent vending, ATM and point-of-sale(POS) terminals) and industrial control systems.

The following highlight the features of the LEC-7230-

CT1 system:

•

Dual HDMI and VGA video output powered by Intel®

HD Graphics

•

Dual 10/100/1000 Mbps LAN ports

•

6 USB ports (3 from add-on board)

•

Support 2.5" SATA HDD/SSD storage

•

Two RS-232/422/485 serial COM ports supporting hardware control via DB9 connectors

•

Audio input and output through Mic-in and Line-out jack

•

Fanless design

•

Integrated SIM card reader

•

•

Dustproof

Wide operating temperature from -20-55°C

System Specifications

Processor Options

Chipset

BIOS

System

Memory

USB

Super I/O

Expansion Bus

OS Support

Storage

Networking

Display

Audio

LEDs

Physical

Characteristics

Environment

Power

Standard and

Regulation

Reliability

Sockets

HDD/SSD Support

LAN

Controller

Intel® Bay Trail Celeron® Processor J1900 4C (2M Cache, up to

2.42 GHz) 10W

None

AMI SPI Flash BIOS

1 x SO-DIMM socket for up to

1066/1333 4GB DDR3L SDRAM

1 x USB 3.0 port

2 x USB 2.0 Type-A ports

3 x USB 2.0 ports from add-on board

1x LPC Super I/O Fintek F81865F

Mini-PCIe x 1, with SIM card reader

Microsoft Embedded Windows 8

Standard, Ubuntu LTS 12.04

1 x 2.5” HDD/SSD drive bay

2 x 10/100/1000Mbps,

Autosensing,RJ-45

Intel i210 x 2

Graphics Controller

Display Interface

Video Decode

Acceleration

Video Encode

Acceleration

Codec

Output

Housing

Intel® Integrated Graphics Media

Accelerator

VGA x 1 (1600x1200@60 24bpp),

HDMI x1 (1920x1080)

MPEG2, H.264, MVC, VC-1/WMV9

@1080p, VP8

MPEG2, H.264 @ 1080p

Audio Codec ALC-886 HD Audio,

Low Power Audio

1x green phone-jack connector for audio line-out

1x pink phone-jack connector for audio mic-in

Power, HDD active, 3G active (if 3G mini-card inserted)

Aluminum

Dimensions (WxHxD)

Mounting Options

Operating Temperature

198.0 x 144.8 x 48.0, unit: mm

Rack, VESA, DIN-rail and Wall mount

-20~55°C (PCBA needs thermal solution on heat-sink or cased design;)

5 to 95% (non-condensing)

Ambient Relative Humidity (non-condensing)

Input Voltage

Connector

AC Adapter

+12 V +/- 5% DC

DC jack with lock

EMC CE/FCC

Green product

Alter tool t

Automatic Reboot Trigger

RoHS

Built-in buzzer and RTC (real-time clock) with battery lithium backup

Watchdog Timer 256 level time interval system reset, software programmable

Package Contents

Your package contains the following items:

•

LEC-7230-CT1 Fanless Embedded System

•

Power adapter : 0P0W060122002

•

Drivers and User’s Manual CD : S09OADA92H100

Standard Accessories

0P0W060122002 AC power adapter

Optional Power Cords

080W240318306

US Power Cord

080W240318305

Schuko (EU) Power Cord

080W240318301

UK Power Cord

080W240318307

China Power Cord

080W240318309

Japan Power Cord

Optional Mounting Kit

SE9ESA900R100

Wall Mount 4

PE9ESA8300100

VESA Mount

SE9ESA8310100

Rack Mount

090W405000001

DIN Rail Mount

Optional Accessories

0TAWMC8090Z01 3G card

0TAWWPER11Z01 WiFi card

0TAWWPER12Z01 WiFi card

080W1Q0001501 WiFi card

0TZW000000039 WiFi card

080W0Q0001501 WiFi card

0TZW000000072 WiFi card

Green MC8090 PCI EXPRESS MINI CARD

3G MODULES SIERRA

Green WPER-116GN 802.11bgn Mini

PCIe module with HMCE-101(Half-Mini-

Card extender) SparkLAN

Green WPEA-121N 802.11abgn Mini PCIe module with HMCE-101(Half-Mini-Card extender) SparkLAN

Internal Cable for Wifi

External Antenna for WiFi

Internal Cable for 3G

External Antenna for 3G

Chapter 2:

System Components

System Drawing

Mechanical dimensions of the LEC-7230-CT1

Unit: mm

Block Diagram

VGA x 1

+12 Vdc input

SATA 2.5” drive bay x 1

USB3.0 x 1

USB2.0 x 2

Mini PCI Express with

SIM card reader x 1

USB2.0

Intel® Bay

Trail

Celeron®

CPU J1900

Valley View

SoC

Intel I210 x 2

HDMI x 1

Audio

Mic-in & Line-out

Codec

Super I/O phone jack

DB9 RS-232/422/485 x2

Pin header RS-232 x2

UARTx2

MIO

HSIC

PCIe Lane x 1

USB Hub

Design

Reservation

(HSIC)

Design

USB2.0 x2

USB2.0 x1

Front Components

F1

F2

F3

F4

F5

F6

F7

F4

Component

F1 Reset

F2 MIC IN/LINE OUT

F3 USB 3.0 Port

F4 Four USB 2.0 Ports

F5 Two 10/100/1000Mbps LAN ports

LINK/ACT

F6 HDD (Yellow)

3G Status (Green) and

Power LED (Green) sPEEd

F7 Power Button with dual LED

Description

Reset switch

Connect the audio devices to these ports. The

Microphone and line out port are provided by

Realtek ALC 886-GR.

An USB 3.0 type A connector.

Double-stacked USB 2.0 type A connectors

Two additional USB 2.0 ports by LEK-

IOA11. add-on board

Two RJ-45 (network) jacks with LED indicators are as described below.

Remarks

Please refer to the USB pin definition on LEK-IOA11 for the 2 additional USB ports

LINK/ACT (Yellow)

• On/Flashing: The port is linking and active in data transmission.

• Off: The port is not linking.

SPEED (Green/Yellow)

• Yellow: The connection speed is 1000Mbps.

• Green: The connection speed is 100Mbps

• Off: The connection speed is 10Mbps.

HDD

• Blinking: data access activities

• Off: no data access activities

3G Status

• Blinking: 3G transmission activities

• On: 3G expansion card exists

• Off: no 3G expansion card present

Power

• On: The computer is on.

• Off: The computer is off .

ATX Power-on button with LEDs: Standby mode in Red; Power-on mode in Green

Rear Components

R1

R2

R3

R4

R5

R1 HDMI

Component

R2 VGA Port

R3 Serial COM Ports

R4 Power Adapter Socket

R5 USB

Description

The HDMI (High-Definition Multimedia Interface).

This port can support up to 1920x1080 resolution.

The displays can support VGA up to 1600x1200 resolution.

The serial COM ports are in DB-9 connector type with signals RS232/422/485 configured with automatic hardware flow control D-SUB connector that manages the connection of serial peripherals. To switch among

RS232/422/485, use the BIOS menu.

DC-in 12V. Only use the power adapter supplied with the LEC-7230-CT1 System

Additional USB2.0 port by the LEK-IOA11 add-on board

Remarks

WARNING: Improper installation can cause injury or property damage.

For proper and safe operation use in field site with AC Power, please follow these instructions:

1. Securely plugged and locked the DC-Jack to the machine

2. Connect the AC adapter power cord into a standard 110v/220v AC outlet

Chapter 3:

Board Layout

External Connectors

The following picture highlights the location of the external ports. Refer to the table 3.1 Connector List for more details.

HdMI1

VGA1

COM1

COM2

LAN1

LAN2

UsB1 UsB2 LOUT1

MIC1

Internal Connectors and Jumpers

The following picture highlights the location of internal connectors and jumpers. Refer to the table 3.1 Connector

List for more details.

JCMOs1

JLPC1

JsPI1

JRI1 JRI2 sATA1 sATAPWR1

JKBMs1

Add-on Card

The add-on card (LEK-IOA11), enabled by MIO, provides 3 additional USB2.0 ports for LEC-7230-CT1.

dual UsB2.0 ports (UsB1)

Add-on card

UsB2.0 port

Connectors and Jumpers List

The tables below list the function of each of the board jumpers and connectors by labels shown in the above section. The next section in this chapter gives pin definitions and instructions on setting jumpers.

Table 3.1 Connector List for LEB-7230-CT1 Board

Labels

COM1/COM2

HDMI1

JCMOS1

JKBMS1

JLPC1

JRI1/2

JSPI1

MPCIE1

SATA1

SATAPWR1

SIM1

USB1

USB2

VGA1

Function

RS232 Serial Ports COM1 and COM2

High-Definition Multimedia Interface Port

Clear CMOS Jumper

PS/2 Keyboard & Mouse Connector

Low-pin Count Interface

COM1/COM2 Pin 9 Signal Selection

SPI ROM Interface (for debug use only)

Mini-PCIe Connectors (with SIM1)

Serial-ATA Connector (SATA1)

SATA HDD Power Connector

SIM Card Reader

USB 2.0 Type A Dual Port

USB 3.0 Type A Port

VGA Connector

Jumper and Connectors

RS-232/422/485 Serial Port (COM1 and COM2): It is an RS-232/422/485 port with automatic hardware flow control through a D-SUB9 connector.

Select COM1/COM2 Pin 9 Function (JRI1/JRI2): The pin 9 of COM1 and COM2 can be altered by JRI1 and JRI2 respectively according to the following jumper settings.

JRI1: COM1 JRI2: COM2

1 2 3 4 5

2 4 6

6 7 8 9

Default

6

4

2

5

3

1

1 3 5

Pin No.

7

8

5

6

9

3

4

1

2 signal

Rs-232 data Carrier detect ( dCd # )

Receive data ( RXd )

Transmit data ( TXd ) data Terminal Ready ( dTR # )

Ground ( GNd ) data set Ready ( dsR # )

Request To send ( RTs # )

Clear To send ( CTs # )

Ring Indicator ( RI # )

+5V

+12V

2 4 6

2 4 6

6

4

2

6

4

2

5

3

1

5

3

1

Pin No.

3

4

1

2

5 signal

Rs-422

TXd-

TXd+

RXd+

RXd-

GNd

Pin No.

3

4

1

2

5 signal

Rs-485 dATAdATA+

GNd

1 3 5

SW1/SW4

Note:

To switch among RS-232, 422, 485 communication protocols, use the BIOS menu.

Jumper Setting

Function

RI# (default)

+5V

+12V

1-2

3-4

5-6

Clear CMOS jumper (JCMOS1): It is for clearing the

CMOS settings.

1

2

3

Pin No.

1-2

2-3 signal

Normal (default)

Clear CMOs

Serial-ATA Connector (SATA1): It is for connecting a 2.5’’ harddisk to serve as your system’s storage. It can support

SATA II which features Data transfer rates up to 3.0 Gb/s

(300 MB/s).

sATA1

3

2

1

5

4

7

6

Pin No.

1

2

3

6

7

4

5 signal

GNd

TX0_P

TX0_N

GNd

RX0_N

RX0_P

GNd

VGA (VGA1)

11 12 13 14 15

4-pin Serial-ATA Power Connector (SATAPWR1): It is for connecting the SATA power cord.

Pin

1

1 2 3 4 5

Pin

6 signal

GNd

Pin

11 signal

NC

1 2 3 4

Pin No.

1

2

3

4

2

3

4

5 signal

Red Color signal

Green Color signal

Blue Color signal

Reserved

GNd

7

8

9

10

GNd

GNd

+5V

GNd

19 1

12

13

14

15

HDMI Connector (HDMI1): High-Definition Multimedia

Interface Connector ddC dATA

HsYNC

Dual USB 2.0 Port (USB1):

USB 3.0 Port (USB2)

VsYNC ddC CLK

1 2 3 4

5 6 7 8

Pin No.

1

2

3

6

7

4

5

8

9 signal

12V

GNd

GNd

+5V signal

+5V dATAdATA+

GNd ssRXssRX+

GNd ssTXssTX+

18 2

Pin

1

3

5

7

9

11

13

15

17

19 signal dATA2+ dATA2-

GNd dATA0+ dATA0-

GNd

N.C

ddC CLK

GNd

HPd

Pin

2

4

6

8

10

12

14

16

18 signal

GNd dATA1+ dATA1-

GNd

CLK+

CLK-

N.C

ddC dAT

HdMI_VCC

PS/2 Keyboard and Mouse Connector (JKBMS1)

5

7

1

3

Pin NO. description

1 VCC

3

5

7

MsdATA

KBdATA

GNd

SIM Card Reader (SIM1)

6

8

2

4

Pin NO.

2

4

6

8 description

MsCLK

KEY

KEY

KBCLK

C5

C7

C1

C3

Pin NO.

C1

C2

C3 signal

UIM_PWR

UIM_RsT#

UIM_CLK

Pin NO.

C5

C6

C7 signal

GNd

UIM_VPP

UIM_dATA

33

35

37

39

41

43

45

25

27

29

31

17

19

21

23

47

49

51

Mini PCI Express Connector (for 3G card with PCI Express 1X and USB 2.0 signals and

a SIM card reader, MPCIE1):

7

9

11

13

15

PIN

1

3

5 signal

WAKE#

COEX1

COEX2

CLKREQ#

GNd

REFCLK-

REFCLK+

GNd

8

10

12

14

16

PIN

2

4

6 signal

+3.3Vaux

GNd

+1.5V

UIM_PWR

UIM_dATA

UIM_CLK

UIM_REsET

UIM_VPP

Key

RsVd

RsVd

GNd

PERn0

PERp0

GNd

GNd

PETn0

PETp0

GNd

GNd

+3.3Vaux

+3.3Vaux

GNd

RsVd

RsVd

RsVd

RsVd

34

36

38

40

42

44

46

26

28

30

32

18

20

22

24

48

50

52

GNd

W_dIsABLE#

PERsT#

+3.3Vaux

GNd

+1.5V

sMB_CLK sMB_dATA

GNd

UsB_d-

UsB_d+

GNd

LEd_WWAN#

LEd_WLAN#

LEd_WPAN#

+1.5V

GNd

+3.3Vaux

Chapter 4:

Hardware Setup

Preparing the Hardware Installation

To access some components and perform certain service procedures, you must perform the following procedures first.

Installing the System Memory

The motherboard supports DDR3L memory to meet the higher bandwidth requirements of the latest operating system and Internet applications. It comes with one Low-

Voltage Double Data Rate Three (DDR3L) Small Outline

Dual Inline Memory Module (SO-DIMM) socket.

1. Align the memory module’s key with the SO-DIMM socket’s notch.

2. Install the SO-DIMM.

WARNING:

To reduce the risk of personal injury, electric shock, or damage to the equipment, remove the power cord to remove power from the server. The power switch button does not completely shut off system power. Portions of the power supply and some internal circuitry remain active until power is removed.

1. Unpower the LEC-7230-CT1 and remove the power cord.

2. Turn the device upside down.

3. Unscrew the 4 rubber feet from the bottom cover.

4. Open the cover.

Note:

The system can support memory of DDR3L SO-

DIMM up to 4 GB in maximum.

Installing the Wireless Module

1. Align the wireless module’s key with the Mini-PCIe slot notch.

2. Insert the wireless module into the connector diagonally.

3. Fix the wireless module with the screws.

Installing the Disk Drive

The system can accommodate one Serial-ATA disk drive.

Follow these steps to install a hard disk into the system:

1. Align the mounting holes of the HDD/SSD and that on the LEC-7230-CT1 systems as illustrated in the following picture. Fix the hard disk on the system by attaching the screws through the back cover from the outside.

2. Plug the Serial-ATA cable to the disk.

3. Connect the Serial-ATA power and data disk cables to the Serial-ATA power and disk connectors on the main board respectively.

Installing the 3G SIM Card

1. Unlock the SIM card reader first by sliding it outward.

2. Flip the SIM card reader diagonally.

3. Put the SIM card into the reader. The angled corner of the SIM ensures that the card fits only the correct way in the reader. Make sure the ICs will be in contact with the SIM card reader.

4. Close the tray. You should hear a click when the SIM card is locked securely in the SIM card reader.

Unlock

Lock

Note: To remove the SIM card, push the card outward to unlock it.

Appendix A:

Programming Watchdog

Timer

A watchdog timer is a piece of hardware that can be used to automatically detect system anomalies and reset the processor in case there are any problems. Generally speaking, a watchdog timer is based on a counter that counts down from an initial value to zero. The software selects the counter’s initial value and periodically restarts it. Should the counter reach zero before the software restarts it, the software is presumed to be malfunctioning and the processor’s reset signal is asserted. Thus, the processor will be restarted as if a human operator had cycled the power.

For sample watchdog code, see Watch dog in the Driver

and Manual CD