1. Offline investigation of Audio Channel Modeling Laboratory FM-Stereo Demodulation
M. Smith,
Electrical and Computer Engineering,
University of Calgary, Canada
ucalgary.ca

2. Modeling an audio channel using an ADSP21061 processor
11/15/2018
ENCM Post Lab. 0 Hardware Details Copyright M. Smith --

3. ENEL515 Post Lab. 0 Quiz YOU’LL NEED HEADPHONES
Test out VisualDSP software environment using “OFFLINE_SOURCE_DEMO.exe” -- get from ENCM515 Web
Test out VisualDSP hardware environment using “LOCAL_SOURCE_DEMO.exe” -- get from ENCM515 Web
YOU’LL NEED HEADPHONES
Start/finish work on ‘C’ and assembly code version of FMSTEREO_DEMOD for Post-Lab 0 Quiz.
Test Off-Line version using VisualDSP1.0++ and VisualDSP2.0++
11/15/2018
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4. Files needed for Post Lab 0 Quiz
offline_source21061.dxe -- Demonstration OFFLINE Audio Channel Modeling -- FM Stereo Demodulation and simple IIR filter operations
local_source21061.dxe -- Demonstration LOCAL Audio Channel Modeling -- FM Stereo Demodulation
codec_source21061.dxe -- Demonstration CODEC Audio Channel Modeling -- FM Stereo Demodulation
AudioChannelmain2001.c -- Main driver routine for audio modeling laboratories on ADSP21061 SHARC
channelmodels_lab0.c -- Audio Channel Modeling Algorithms for Lab. 0
processdefs.h -- Audio Channel Modeling constants
general_library21061Lite.dlb -- Library of utilties needed for CODEC, OFFLINE and ON_LINE sound sources
offline_library21061Lite.dlb -- Library needed for OFF-LINE audio channel modeling
online_library21061Lite.dlb -- Library needed for LOCAL and CODEC audio channel modeling
ADSP 21061interrupts.ldf -- ADSP21061 Architectural Specifications for EZ-LITE SHARC
clanguage_register_defines.i -- Changes ADSP21O6X register names to something more readable
handout_lab0demo.asm -- Walk through the development of an ADSP assembly language file
11/15/2018
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5. Testing the Audio Channel Modeling hardware environment
Build a directory u:\yourname\encm515\postlab0\debug
Download the following files from “Files need for Post Lab1 Quiz” on the ENCM515 web page
OFFLINE.dxe -- Demonstration OFFLINE Audio Channel Modeling -- FM Stereo Demodulation and simple IIR filter operations
LOCAL.dxe -- Demonstration LOCAL Audio Channel Modeling -- FM Stereo Demodulation
CODEC.dxe -- Demonstration CODEC Audio Channel Modeling -- FM Stereo Demodulation
Most recent files are dated 28 December watch for updates
11/15/2018
ENCM Post Lab. 0 Hardware Details Copyright M. Smith --

6. Test -- VisualDSP
VisualDSP -- Select CONTROL plus DEBUG button in the top menu (ladybird)
From session list select
ADSP ADSP-2106x simulator ADSP 2106x family and Activate
Click OK on File could not be found window as we are not using the default executable name (test.dxe) associated with the Visual DSP project
Download OFFLINE_SOURCE.dxe file from postlab0\ debug directory
We now need to display the input and output files associated with this executable
Select View | Debug Windows | Plot
Browse and Add the following arrays to the Plot window using Memory DM, count 768, stride 1, data int for each array
input_array -- will show square source when run
output_left -- will show filtered FM-demodulated left channel when run (Positive components in this case)
output_right-- will show FM-demodulated right channel when run (Negative components in this case)
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7. Files used in every lab. 2001main.c
Activates the sound sources and audio channel modeling -- Change only ProcessSound()
channelmodels.c and fasterchannelmodels.asm
The algorithms used in the audio channel modeling
processdefs.h
Constants used to define the channel modeling operations -- This are hardcoded into libraries -- don’t change the values
ADSP-21061interrupts.ldf
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ENCM Post Lab. 0 Hardware Details Copyright M. Smith --

8. Main Program MAKE NO CHANGES TO THIS CODE SECTION
#define DELAYUNITS 44
#define IIR_COEFF 0.1
AttachSoundSource(whichsource, DELAYUNITS, IIR_COEFF);
// ONLY RETURNS FROM THIS FUNCTION FOR OFF-LINE OPS
// For LOCAL-SOURCE and CODEC-SOURCE -- launches interrupts
// Only gets here with OFFLINE_SOURCE -- However other sources do equivalent
while (ReadSoundSource(&channel_one, &channel_two) != 0){
// Checks if OFFLINE_SOURCE sounds are finished
ProcessSound(channel_one, channel_two, &left_channel, &right_channel);
WriteSoundSource(left_channel, right_channel); }
printf("main() -- While loop has exited for OFFLINE_SOURCE\n");
MAKE NO CHANGES TO THIS CODE SECTION
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ENCM Post Lab. 0 Hardware Details Copyright M. Smith --

9. Process Sound( )
void ProcessSound(int channel_one, int channel_two, int *left_channel, int *right_channel) {
if (sound_source & FM_STEREO)
DecodeFMSTEREO(channel_two_strength, &channel_one, &channel_two);
if (sound_source & OVERSIMPLEIIR)
OverSimpleIIR(/* IIRcoeff */ process_var2, &channel_one, &channel_two);
if ((sound_source & LEFT_DELAY) == LEFT_DELAY) {
if ((sound_source & MOVEDELAY) == MOVEDELAY)
MemoryMove_LeftDelay(process_var1, &channel_one); }
// Have finished modifying the channels
*left_channel = channel_one;
*right_channel = channel_two;
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10. Key component -- audiochannel.c
#define MAXDELAY 0x80
void MemoryMove_LeftDelay(int process_var1, int *channel_one) {
int count;
static float left_delayline[MAXDELAY] = {0};
// Insert new value into the back of the FIFO delay line
left_delayline[0 + process_var1] = (float) *channel_one;
// Grab delayed value from the front of the FIFO delay line
*channel_one = (int) left_delayline[0];
// Update the FIFO delay line using inefficient memory moves
for (count = 0; count < process_var1; count++)
left_delayline[count] = left_delayline[count + 1]; }
LOOK AT COMPILER, ALGORITHM AND HARDWARE EFFICIENCIES
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11. VisualDSP++ 1.0 IIR filter
INPUT_ARRAY -- SQUARE WAVE to
RIGHT_OUTPUT -- SQUARE WAVE 0 to
LEFT_OUTPUT -- SQUARE WAVE 0 to Which is then low pass filtered
Filter operation involves(implied) float to int conversions with the form
*new_output = (int) ( (1 - a) * *channel + a * old_output); a = 0.1
* channel -- is the value to be processed *new_output -- is the new filtered value old_output -- is the previous filtered value
void OverSimpleIIR(float IIRcoeff, int *channel_one, int *channel_two) {
static int oldy = 0;
*channel_one = *channel_one * IIRcoeff + oldy * (1 - IIRcoeff);
oldy = *channel_one; }
11/15/2018
ENCM Post Lab. 0 Hardware Details Copyright M. Smith --

12. Test -- VisualDSP
Debug -- Select the RUN PROGRAM icon (Small Page with down arrow)
Will see -- Version Information, Source information on the screen etc.
Since simulating within a complicated DSP processor environment, takes some time to FM demodulate and IIR filter 768 points from the input array.
From results can determine -- impulse response, IIR filter time constant etc
Original Square Wave to Channel Left -- L+R, Right -- L -- R
OFFLINE FM-Stereo Modeling approach
Right Channel -- designed as negative components of original signal
Left Channel -- designed as positive components of original signal. Simple RC IIR filter applied after FM-demodulation
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13. ICE hardware --1
TAKE CARE -- THESE ARE VERY EXPENSIVE PROBES -- I want to use them for a number of years!
Look at the set-up for Lab. 0 for the care and handling of the ICE hardware
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14. Test -- hard ware -- 2
VisualDSP -- Select DEBUG button in the top menu (ladybird)
From new session list select
SummitICE21061 (ADSP-21061) ADSP ADSP-21xxxx JTAG Emulator
Click OK on File could not be found window as we are not using the default executable name associated with the Visual DSP project
Download OFFLINE_SOURCE.dxe file from lab0\ debug directory to the board. You may have to use the RESET option in the debug window or the RESET button on the evaluation board if the processor is “hung”
We now need to display the input and output files associated with this executable
Select View | Debug Windows | Plot
Browse and Add the following arrays to the Plot window using Memory DM, count 768, stride 1, data int for each array
input_array, output_left, output_right
Run the program -- should go a lot faster (if you are not still run the simulator by mistake (MFE -- my favourite error)).
11/15/2018
ENCM Post Lab. 0 Hardware Details Copyright M. Smith --

15. General Lab. Process Develop your DSP algorithms
Test your algorithms in a controlled OFF-LINE environment so you can tell that they work
Evaluate IMPULSE or SINEWAVE response for example
Evaluate TIMING of the algorithms
Evaluate expected output against actual output
Once you are getting the expected results in the OFFLINE enviroment then simply “relink” to the on-line_library and try real-time version
11/15/2018
ENCM Post Lab. 0 Hardware Details Copyright M. Smith --

16. Project file configurations
Offline.dpj file
AudioChannelsmain2001.c
channelmodels.c or .asm
ADSP-21061interrupts.ldf
general_library21061.dlb
offline_library21061.dlb
2001main.c is compiled using compiler option
-D WHICHSOURCE= OFFLINE_SOURCE
Once set this option stays set inside this particular .dpj file
local.dpj or codec.dpj files
2001main.c
channelmodels.c or .asm
ADSP-21061interrupts.ldf
general_library21061.dlb
online_library21061.dlb
2001main.c is compiled using compiler option
-D WHICHSOURCE= LOCAL_SOURCE or
-D WHICHSOURCE= CODEC_SOURCE
Once set this option stays set
11/15/2018
ENCM Post Lab. 0 Hardware Details Copyright M. Smith --

17. Parameter set in main.c
// Set the WHICHSOURCE option as -D WHICHSOURCE=??? as a COMPILER option
#if (WHICHSOURCE & OFFLINE_SOURCE)
// whichsource = OFFLINE_SOURCE | SQUAREWAVE | MONO | MOVEDELAY | LEFT_DELAY;
// whichsource = OFFLINE_SOURCE | SQUAREWAVE | MONO | MOVEDELAY | LEFT_DELAY | OVERSIMPLEIIR;
whichsource = OFFLINE_SOURCE | SQUAREWAVE | FM_STEREO | OVERSIMPLEIIR;
// whichsource = OFFLINE_SOURCE | SINEWAVE | MONO | MOVEDELAY | LEFT_DELAY;
// whichsource = OFFLINE_SOURCE | SINEWAVE | MONO | MOVEDELAY | LEFT_DELAY | OVERSIMPLEIIR;
// whichsource = OFFLINE_SOURCE | IMPULSE | MONO | MOVEDELAY | LEFT_DELAY;
// whichsource = OFFLINE_SOURCE | IMPULSE | MONO | MOVEDELAY | LEFT_DELAY | OVERSIMPLEIIR;
#elif (WHICHSOURCE & LOCAL_SOURCE)
// whichsource = LOCAL_SOURCE | MONO;
// whichsource = LOCAL_SOURCE | MONO | MOVEDELAY | LEFT_DELAY;
// whichsource = LOCAL_SOURCE | STEREO;
// whichsource = LOCAL_SOURCE | STEREO | MOVEDELAY | LEFT_DELAY;
whichsource = LOCAL_SOURCE | FM_STEREO;
// whichsource = LOCAL_SOURCE | FM_STEREO | MOVEDELAY | LEFT_DELAY;
#endif
11/15/2018
ENCM Post Lab. 0 Hardware Details Copyright M. Smith --

18. Building the OFFLINE project
Windows -- Programs | Visual |Environment
VisualDSP -- File | New | Project
Save as offlinetesting.dpj in postlab0 directory
Project Options -- KEY
Processor ADSP-21061
Type DSP executable
Configuration Debug
Compiler Options -- Add -D WHICHSOURCE= OFFLINE_SOURCE
Use the + icon to add the five files
Force “rebuild all” option and then download to simulator
11/15/2018
ENCM Post Lab. 0 Hardware Details Copyright M. Smith --

19. Building the LOCAL project
Windows -- Programs | Visual |Environment
VisualDSP -- File | New | Project
Save as localsource.dpj in postlab0 directory
Project Options -- KEY
Processor ADSP-21061
Type DSP executable
Configuration Debug
Compiler Options -- Add -D WHICHSOURCE= LOCAL_SOURCE
Use the + icon to add the five files
Force “rebuild all” option and then download to “real board”
You will need head-phones to hear the sounds
Notice that buttons on the board control activity -- read prompts.
11/15/2018
ENCM Post Lab. 0 Hardware Details Copyright M. Smith --

20. Building the CODEC project
Windows -- Programs | Visual |Environment
VisualDSP -- File | New | Project
Save as codecsource.dpj in postlab0 directory
Project Options -- KEY
Processor ADSP-21061
Type DSP executable
Configuration Debug
Compiler Options -- Add -D WHICHSOURCE= CODEC_SOURCE
Use the + icon to add the five files
Force “rebuild all” option and download to “real board”
You will need head-phones to hear the sounds
You will need cable to go from CD to input
Notice that buttons on the board control activity -- read prompts.
11/15/2018
ENCM Post Lab. 0 Hardware Details Copyright M. Smith --

21. Current “audiochannels.c”
#ifndef SMITH_TEST
void DecodeFMSTEREO(int channel_two_strength, int *channel_one, int *channel_two) {
printf("void DecodeFMSTEREO(int, int *, int *) is developed as part of Pre-Lab 0 Quiz");
printf("\t Try the Smith version by compiling with option -D SMITH_TEST");
exit(0); }
#endif
Post Lab 0 requires
Building and testing the algorithm with “C” version
Building your own “assembly” version
Comparing assembly code generated by “C” and your own
Scheduling the assembly code in MicroSoft Project
11/15/2018
ENCM Post Lab. 0 Hardware Details Copyright M. Smith --

22. Post Lab. 0 Quiz -- Add “C” -- 1
Add the following “C” code to your project to get your FM stereo demodulation module to work inside channelmodels.c
void DecodeFMSTEREO(int channel_two_strength, int *channel_one, int *channel_two) {
int temp_one = *channel_one; int temp_two = *channel_two;
static int comment = 0;
// If Channel Strength is too week then just use channel_one on both channels
if (channel_two_strength < 25) *channel_two = *channel_one;
else {
*channel_one = (temp_one + temp_two) >> 1;
*channel_two = (temp_one - temp_two) >> 1; }
if (!comment) {
printf("Smith DecodeFMStereo() -- FM_STEREO demodulation example");
printf(" Channel_one L + R -- strength %d", channel_one_strength);
printf(" Channel_two L - R -- strength %d", channel_two_strength);
comment = 1;
11/15/2018
ENCM Post Lab. 0 Hardware Details Copyright M. Smith --

23. Post Lab. 0 Quiz -- 2 Remove “C” DecodeFM() link to new file lab0handout.asm
#include <def21060.h>
#include "clanguage_register_defines.i"
// void DecodeFMSTEREO(int channel_two_strength, int *channel_one, int *channel_two);
.segment/dm seg_dmda;
.var comment = 0; // static int comment = 0;
.endseg;
.segment/pm seg_pmco;
.global _DecodeFMSTEREO;
_DecodeFMSTEREO: // void DecodeFMSTEREO(
#define strengthR4 INPAR1
// int temp_one = *channel_one;
#define temp_oneR1 scratchR1
scratchDMpt = INPAR2; // Example code
temp_oneR1 = dm(zeroDM, scratchDMpt); // Example code
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24. Post Lab. 0 Quiz -- 3 Replace “C” with lab0handout.asm
// int temp_two = *channel_two;
#define temp_twoR2 scratchR2
???? Your turn
????
// If Channel Strength is too week then just use channel_one on both channels
// if (channel_two_strength < 25) *channel_two = *channel_one;
// else {
// *channel_one = (temp_one + temp_two) >> 1;
// *channel_two = (temp_one - temp_two) >> 1;
// }
// Rewrite in simpler RISC life format
// Take into account can't compare to constant directly
11/15/2018
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25. Additional hints
There are some additional hints suggested in the rest of the “lab0handout.asm” file
11/15/2018
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26. ENCM515 Post Lab. 0 Quiz
Test out VisualDSP software environment using “OFFLINE_SOURCE_DEMO.exe” -- get from ENCM515 Web
Test out VisualDSP hardware environment using “LOCAL_SOURCE_DEMO.exe” -- get from ENCM515 Web
You’ll need head phones
Build a Visual DSP project -- OFF_LINE source -- your own version (in C) of FMSTEREO_DEMODULATION
Start/finish work on assembly code version of FMSTEREO_DEMOD for Post-Lab 0 Quiz.
11/15/2018
ENCM Post Lab. 0 Hardware Details Copyright M. Smith --

27. Post Lab. 0 Quiz -- 4 Replace “C” with lab0handout.asm
// constant = 25;
// Compare channel_two_strength with constant
// if greater or equal go to ELSE_CODE (watch delayed jump)
// otherwise fall through to IF_CODE
// IF_CODE: *channel_two = *channel_one;
// JUMP ALWAYS TO END_IF (watch delayed jump)
// ELSE_CODE
// temp = temp_one + temp_two;
// *channel_one = temp >> 1;
// temp = temp_one - temp_two;
// *channel_two = temp >> 1;
// END_IF
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ENCM Post Lab. 0 Hardware Details Copyright M. Smith --

28. Post Lab. 0 Quiz -- 5 Replace “C” with lab0handout.asm
// constant = 25; Which scratch register has become available?
#define constantR0 retvalueR0 // Example code
constantR0 = 25
// Compare channel_two_strength with constant
????
// if greater or equal go to ELSE_CODE (watch delayed jump)
// otherwise fall through to IF_CODE
IF GE JUMP(PC, ELSE_CODE)(DB); // Example code
NOP; // Example code
// IF_CODE: *channel_two = *channel_one;
// Can translate this as *channel_two = temp_one
// Need to use INPAR3 to specify destination address
IF_CODE: // Example code
scratchDMpt = INPAR3; // Example code
// JUMP ALWAYS TO END_IF (watch delayed jump)
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29. Post Lab. 0 Quiz -- 6 Replace “C” with lab0handout.asm
// ELSE_CODE
// temp = temp_one + temp_two;
// *channel_one = temp >> 1;
// temp = temp_one - temp_two;
// *channel_two = temp >> 1;
ELSE_CODE: // Example code
#define tempR0 retvalueR0 // Example code
????
etc
// END_IF
END_IF:
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ENCM Post Lab. 0 Hardware Details Copyright M. Smith --

30. Post Lab. 0 Quiz -- 7 Replace “C” with lab0handout.asm
// The following code for printf( ) is easier handled by swinging back into "C"
// Note that the processor architecture has been modified to allow more efficient
// for use with "C-language" -- CJUMP instruction modifies R2
// I7 used as CTOPstack pointer -- this is not the same as SP which is part of BRANCH LOGIC
// I6 used as FP (frame pointer)
// BIG WARNING -- Note that this code is at the end of the subroutine so that
// it no longer matters that INPAR1, INPAR2 and INPAR3 may be destroyed during
// a call to another subroutine
// if (!comment) {
#define commentR1 scratchR1
commentR1 = dm(comment); // Remember RISC architecture
commentR1 = pass commentR1; // Set the ALU flags for testing
// !comment means comment != 0 -- A PSP GOTCHA!
// NOTE -- NOT pass(commentR1) -- A PSP GOTCHA!
IF NE JUMP(PC, END_PRINTF) (DB); // Watch the delayed instructions
NOP;
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ENCM Post Lab. 0 Hardware Details Copyright M. Smith --

31. Post Lab. 0 Quiz -- 8 Replace “C” with lab0handout.asm
// The following code for printf( ) is easier handled by swinging back into "C"
IF_PRINTF:
// comment = 1; // Remember RISC architecture
commentR1 = 1; // Can't put a 1 directly to memory
dm(comment) = commentR1;
// SwitchBack2C(channel_two_strength)
dm(CTOPstack, minus1DM) = INPAR1;// Push INPAR1 onto "C" stack C_OUTPAR1
// Note that this is not the same as OUTPAR1 for a non-”C”call (R4)
.extern _SwitchBack2C;
cjump _SwitchBack2C (DB); // Warning cjump also causes R2 <- FP (I6)
dm(CTOPstack,minus1DM) = r2; // Warning -- this is not expected R2
dm(CTOPstack,minus1DM) = pc;// This is ADSP21061 "C-langauge" JSR
// Note that two parameters are pulled from the "C" stack during the "C-return"
modify(CTOPstack, plus1DM); // Destroy what might be left of C_OUTPAR1
11/15/2018
ENCM Post Lab. 0 Hardware Details Copyright M. Smith --

32. Post Lab. 0 Quiz -- 9 Replace “C” with lab0handout.asm
// Handling a series of printf( ) is best handled in "C" -- However this is what it would like
// Note that would have to hand-translate the format statement into ascii values
// printf("Smith DecodeFMStereo() -- FM_STEREO demodulation example");
scratchR1 = FORMAT1_LABEL; // Starting address of printf format
dm(CTOPstack,minus1DM) = scratchR1; // Not that is not the stack controlled by SP
.extern _printf;
cjump _printf (DB); // Warning cjump also causes R2 <- FP (I6)
dm(CTOPstack,minus1DM) = r2; // Warning -- this is not R2
dm(CTOPstack,minus1DM) = pc; // This is "C-langauge" JSR
modify(CTOPstack,plus1DM); // Note that only one parameter left on the "C" stack
END_PRINTF: scratchPMpt =dm(-1,FP); // } -- Return to "C" code
jump (plus1PM,scratchPMpt) (DB); nop; RFRAME;
.endseg;
.section/dm seg_dmda; //DATA
FORMAT1_LABEL:
.var FORMAT1_STRING[ ] =83,109,105,116,104,32,68,101,99,111,100,101,70,77,83,116,
101,114,101,111,40,41,32,45,45,32,70,77,95,83,84,69 etc
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