DSP Output Board

DSP Output Board
DSP Output Board
www.matrixtsl.com
EB086
Contents
About This Document
General Information
Board Layout
Testing This Product
Circuit Description
Circuit Diagram
2
3
4
4
7
8
About This Document
This document concerns the E-blocks DSP
Output board with code EB086 version 1.
The order code for the DSP Output board
product is EB086.
1. Trademarks and copyright
PIC and PICmicro are registered trademarks of Arizona
Microchip Inc. E-blocks is a trademark of Matrix
Technology Solutions Ltd.
2. Disclaimer
The information provided within this document is
correct at the time of going to press. Matrix TSL reserves
the right to change specifications from time to time.
3. Testing this product
It is advisable to test the product upon receiving it to
ensure it works correctly. Matrix provides test procedures
for all E-blocks, which can be found in the Support
section of the website.
4. Product support
If you require support for this product then please
visit the Matrix website, which contains many learning
resources for the E-blocks series. On our website you will
find:
•
•
•
•
2
How to get started with E-blocks - if you are new to
E-blocks and wish to learn how to use them from the
beginning there are resources available to help.
Relevant software and hardware that allow you to use
your E-blocks product better.
Example files and programs.
Ways to get technical support for your product, either
via the forums or by contacting us directly.
Copyright © Matrix Technology Solutions Ltd.
General Information
1.Description
2.Features
The DSP Output board allows the exploration
of DSP (Digital Signal Processing) style digitally
sampled analogue waveforms such as audio
or feedback control signals. The board features
multiple adjustable amplifier stages, a high
speed 16-bit digital to analogue converter DAC,
a configurable low pass filter circuit and multiple
scope test points so you can monitor the signal
at various stages in the output chain. The board
also has a LED output which detects is the signal
is being over amplified and therefore if data is
potentially being lost. Using this board it should
be possible to configure almost any output
analogue representation of the digital signal so
that it can be used in any external circuitry.
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On-board 100Ksps 16-bit DAC
Eight active amplifier circuits
Configurable active low pass filter circuit
Scope test points
On-board speaker
On-board mono line out jack
3.
3.3V system compatibility
The board is compatible with 3.3V and 5V
systems.
4.
Block diagram
Modes
Variable
Control 22KHz 3.4KHz
Bypass
Pot
E-blocks
Plug
E-blocks
Patch
On-Board
DAC
Input
Selection
Jumper
0.1 - 2 X
Gain
Low Pass
Filter
Control
Pot
Volume
Control
Pot
Output
Selection
Jumper
On-Board
Speaker
Line Out
Clip
Detection
LED
3
Copyright © Matrix Technology Solutions Ltd.
Board Layout
3
1
2
5
4
9
11
12
6
7
9 Way D-type Plug
Patch system
On-Board High Speed 16-bit DAC
+V 2mm Socket
Input supply voltage screw terminals
Quad Op-Amp IC x 2
Clip Detection Scope Pin
Clip Detection LED
Variable Filter Control Potentiometer
Variable Gain Control Potentiometer
8
15
19
17
13
10
1)
2)
3)
4)
5)
6)
7)
8)
9)
10)
16
14
18
20
11) Low Pass Filter Selection Jumper
12) Filtered Signal Scope Pin
13) PWM / DAC Input Selection Jumper
14) Gain Signal Scope Pin
15) Input Signal Scope Pin
16) Loudspeaker driver IC
17) Speaker / Lineout Output Selection
Jumper
18) Volume Control Potentiometer
19) Onboard Speaker
20) Line Out Jack Socket (mono)
Testing This Product
The following program will test the operation of the DSP
Output E-block.
The test file can be downloaded from www.matrixtsl.
com.
1.
System Setup
Oscilloscope
Headphones / Earphones
Multi-programmer board (EB006) with:
4
EB006 Options
Power supply
PICmicro device
SW1 (Fast/Slow)
SW2 (RC/Xtal)
Xtal frequency
Port A
Port B
Port C
Port D
Port E
Test program
Setting
External, 14V
16F877A
Fast
Xtal
19.6608MHz
LED board EB004
DSP Out board EB086
DSP_Output.hex
Copyright © Matrix Technology Solutions Ltd.
Testing This Product
1
Ensure that the Multiprogrammer is in correct
configuration.
-
Fast mode (SW1 towards the center of the board).
-
XTAL mode (SW2 towards the center of the
board).
-
Ensure that a 19.6608MHz crystal is inserted in
the Multiprogrammer board.
2
Insert the LED board (EB-004-00-1) into Port B of
the Multiprogrammer.
3
Program the a PIC16F877A with the test program
“DSP_Output.hex”.
4
Insert the DSP Output board into Port C of the
Multiprogrammer jumper settings - B, Bypass, DAC, Line
out.
5
Connect wire from “+V” of DSP Output board to
“+V” of Multiprogrammer.
6
Attach scope channel A to the test point Audio
In.
7
Attach scope channel B to the test pint Audio
Gain.
8
Move the Gain potentiometer fully anti clockwise,
the output signal should be sat at 2.5V with a peak to
peak voltage of less than 1V. The Clip LED should be off.
9
Move the Gain potentiometer fully clockwise, the output signal should now go from 0V to 5V in an almost
square wave. The Clip LED should appear to be constantly on.
10
11
5
Move scope channel A to the test point Audio Filter.
Keeping the gain set fully clockwise, change the filter jumper setting to 3.4KHz.
Copyright © Matrix Technology Solutions Ltd.
Testing This Product
12
Keeping the gain set fully clockwise, change the filter jumper setting to 22.1KHz.
13
Keeping the gain set fully clockwise, change the filter jumper setting to variable, adjust the filter pot so that
it is fully clockwise.
14
Keeping the gain set fully clockwise, adjust the filter pot so that it is fully anti-clockwise.
15
16
Move scope channel B to the test point Clip.
The Clip signal should be high whenever the filter signal is in the lower 5% of the voltage range. 0 – 0.5V.
17
Finally remove the scope probes and connect the headphones to the audio out socket. ( Warning - do not
place headphones over your ears as the output may be loud ).
18
Change the volume control pot and ensure the volume changes with the pot position.
19
Change the output source from line out to Speaker using the jumper.
20
Again adjust the volume control and ensure that the volume changes with the pot position.
6
Copyright © Matrix Technology Solutions Ltd.
Circuit Description
1.Description
2.
The circuit board consists of 5 digital I/O lines on a
‘downstream’ 9-way D-type plug. This routes the various
signals from the output board to the microcontroller
on the ‘upstream’ E-blocks programmer board. The
PWM signal is the raw pulse width modulates digital
version of the analogue output signal provided by the
Microcontroller. The CS, MOSI and SCK pins are used to
communicate with the on-board DAC IC. The CLIP signal
is the same output signal which drives the Clip LED so
the microcontroller can warn if portions of the signal are
potentially being lost.
The on-board DAC is a AD5662 IC and can be referenced
by using the SPI Legacy component in Flowcode or you
can output the analogue signal directly using the PWM
module on-board your microcontroller device. There is
an example of how to use the SPI component to send the
waveform data to the on-board DAC available as part of
the main set of Flowcode examples.
SPI based jumper settings.
Jumper Setting A Jumper Setting B
PIC16F88
PIC16F877A
PIC16F1939
Patch
Any Device
Any Device
Individual pin jumper settings.
Pin
Function
PWM
CS
MOSI
SCK
CLIP
7
Jumper
Setting A
Bit-3
Bit-7
Bit-2
Bit-4
Bit-6
Jumper
Setting B
Bit-2
Bit-7
Bit-5
Bit-3
Bit-6
Patch
Patch
Patch
Patch
Patch
Patch
3.
DAC Operation
Filter Operation
The on-board low pass filter has several operational
modes which are selected by moving the jumper on
J3. The filter’s response is that so that by the cutoff
frequency the signal has been attenuated by 50%.
Filtering is important because of issues when converting
digital signals into analogue signals such as quantization
errors and high frequency digital noise. By providing a
low pass filter on the output it is possible to overcome
some of these restraints.
•
Bypass – Full bypass, no filtering is performed on
the signals.
•
3.4KHz – Active filter with cutoff frequency at
3.4KHz allowing for low quality phone style audio quality.
•
22.1KHz - Active filter with cutoff frequency at
22.1KHz allowing for high quality CD style audio quality.
•
Variable – Passive filter with adjustable cutoff
frequency ranging from approx. 100KHz to several Hz.
Copyright © Matrix Technology Solutions Ltd.
Circuit Diagram
8
Copyright © Matrix Technology Solutions Ltd.
Matrix Technology Solutions Ltd.
The Factory
33 Gibbet Street
Halifax, HX1 5BA, UK
t: +44 (0)1422 252380
e: sales@matrixtsl.com
www.matrixtsl.com
EB086-30-1
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