EBC Exercise 18 Using the DSP for Audio Processing - Revision history

Richarsm: /* Assignment - Experiment with the code */

2012-09-22T00:52:10Z

‎Assignment - Experiment with the code

2012-09-17T15:13:05Z

‎Make

2012-09-17T15:05:07Z

‎Examine the Files

2012-09-17T15:04:40Z

‎Examine the Files: Added git clone c6run

2012-07-17T19:30:04Z

2012-06-20T05:04:24Z

‎Make

2012-06-20T05:03:37Z

‎Examine the Files: Removed info about setting up git

2012-05-31T14:05:29Z

‎Assignment - Experiment with the code

2012-05-31T14:04:33Z

‎Explore the Stub Files

2012-05-31T14:03:33Z

‎Sharing Memory

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 * There are places in the code where timing can be displayed.  Remove the comments and display the times.  How often is the main loop executed?  How long does the DSP take? What's the overhead for the DSP?
 * Try making the DSP do more than pass through.  For example, zero out the left channel. Does sound stop coming out?
-* Try changing the sampling rate and buffer sizes.  What setting cause the buffers to overflow or underflow?
+* Try changing the sampling rate and buffer sizes.  What setting causes the buffers to overflow or underflow?
 * Switch the input to the microphones on the web cam and listen to your voice.
 * Implement a frequency inverter by multiplying every other element by -1.

@@ Line 34: / Line 34: @@
 Before the first make the paths need to be set up.  Do this:
   beagle$ '''source c6run_build/environment.sh'''
   beagle$ '''c6run_build/loadmodules.sh'''
@@ Line 40: / Line 41: @@
 Be sure to source the environment.sh file every time you start a new terminal.  Source the loadmodule.sh file every time you reboot your Beagle.
 Run make, but do it like this so you can see what it creates:
   beagle$ '''make clean'''
   beagle$ '''ls'''

@@ Line 17: / Line 17: @@
   beagle$ '''cd lab06d_audio_c6run'''
   beagle$ '''ls'''
 These are the same files as used in the previous audio thru lab.  The files audio_process.c and audio_process.h are new.  audio_thread.c has been changed slightly. Makefile is completely different.

@@ Line 17: / Line 17: @@
   beagle$ '''cd lab06d_audio_c6run'''
   beagle$ '''ls'''
 These are the same files as used in the previous audio thru lab.  The files audio_process.c and audio_process.h are new.  audio_thread.c has been changed slightly. Makefile is completely different.

@@ Line 34: / Line 34: @@
 Before the first make the paths need to be set up.  Do this:
-  beagle$ '''source ~/c6run_build/environment.sh'''
+  beagle$ '''source c6run_build/environment.sh'''
-  beagle$ '''source ~/c6run_build/loadmodules.sh'''
+  beagle$ '''c6run_build/loadmodules.sh'''
 We are now dealing with two C compilers.  One for the ARM the other for the DSP.  The first source above sets PATHs for each of the compilers. Take a look at environment.sh to see the details.  The most interesting part is PLATFORM_CFLAGS, which we'll discuss later. The second source (loadmodules.sh) loads some kernel modules that are needed to support the DSP. Take a look at it, we'll explain some of it later.

@@ Line 9: / Line 9: @@
 == Examine the Files ==
-* Get the files from the git repository
+Make sure you have the most up to date versions of the files.
- beagle$ '''git clone git@github.com:MarkAYoder/BeagleBoard-exercises.git exercises'''
+  beagle$ '''cd ~/exercises'''
-or if you've already git'ted them, make sure you have the most up to date versions.
   beagle$ '''cd exercises'''
   beagle$ '''git pull'''
 * Change directories to AudioThru/lab06d_audio_c6run.

@@ Line 206: / Line 206: @@
 Now that you have something working, play around a bit.  git is installed so you can preserve the present contents of the files with:
-<pre>
-# git add Makefile audio_input_output.c audio_process.c audio_thread.c
+ beagle$ '''git add Makefile audio_input_output.c audio_process.c audio_thread.c'''
-# git commit -m "My changes"
+ beagle$ '''git commit -m "My changes"'''
-</pre>
 If needed you can use git to retrieve the original version of the files.

@@ Line 174: / Line 174: @@
 Then recompile everything:
-  $ make dsp_clean
+  beagle$ '''make dsp_clean'''
-  $ make dsp_exec
+  beagle$ '''make dsp_exec'''
-  $ ls -sh
+  beagle$ '''ls -sh'''
 Many interesting files appear. -debug.dsp_image.map show the memory map for the DSP. To edit it you need to do:
-  $ gedit ./-debug.dsp_image.map
+  beagle$ '''gedit ./-debug.dsp_image.map'''
 The ./ is needed, otherwise gedit will think -debug is an option.
 To see how the DSP is handled on both the ARM and DSP side, look in the '''dsp_lib''' directory.
-  $ cd dsp_lib
+  beagle$ '''cd dsp_lib'''
-  $ gedit *.c
+  beagle$ '''gedit *.c'''
 These two stub files show what's happening on the ARM side (audio_process.gpp_stub.c) and the DSP side (audio_process.dsp_stub.c).

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 So where does cmem allocate the memory? There is a section of the Beagle's RAM that Linux doesn't control.  Try this:
-  $ cat /proc/cmdline
+  beagle$ '''cat /proc/cmdline'''
   console=tty0 console=ttyS2,115200n8 consoleblank=0 mpurate=auto buddy=none camera=lbcm3m1 vram=24M omapfb.mode=dvi:hd720
   ''mem=99M@0x80000000 mem=384M@0x88000000''
@@ Line 138: / Line 138: @@
 What you see are the arguments that were passed to the Linux kernel when it first started.  The '''mem=''' arguments are telling it what memory it can use. 99M bytes start at 0x8000 0000 and another 384M start at 0x8800 0000.  Where does the first block of addresses end?
-  $ bc
+  beagle$ '''bc'''
-  obase=16
+  '''obase=16'''
-*1024*1024
+  '''99*1024*1024'''
   ''6300000''
-  ibase=16
+  '''ibase=16'''
-  6300000+80000000
+  '''6300000+80000000'''
   ''86300000''
 So the block ends at 0x86300000.  cmem controls the memory between that and 0x8800 0000. How does cmem know that?  Look in ~/c6run_build/loadmodules.sh.  You find: