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Summary: This module explains debugging and troubleshooting strategies for Code Composer Studio.
Code Composer provides a rich debugging environment that allows you to step through your code, set breakpoints, and examine registers as your code executes. This document provides a brief introduction to some of these debugging features.
Breakpoints are points in the code where execution is stopped and control of the DSP is returned to the debugger, allowing you to view the contents of registers and memory. Breakpoints can be activated or deactivated by double-clicking on any line of code in the disassembly window.1
You may also want to step through your program code, executing one line at a time, to follow branches and watch memory change with the results of calculations. This can be done by choosing the "Step Into" or "Step Over" menu options from the "Debug" pull-down menu. (Unlike "Step Over," "Step Into" traces subroutine calls caused by "call" opcodes.)
Like most DSPs, the DSP we are using is a pipelined
processor, which means that instructions execute in several
stages over several clock cycles. Unfortunately, our
debugger does not "flush" the pipeline of all current
instructions when it halts your program; i.e., the DSP does
not execute all remaining stages of instructions. As a
consequence, when a program halts, the register values shown
in the register and memory windows may not actually the last
values written. Often, the values shown correspond to
values written several cycles before the current
instruction. If it is necessary to know the exact contents
of the registers at any particular point in the program
flow, simply insert three or more nop (no
operation) instructions into your program after the
instruction in question. Then, to debug, execute the
instruction in question and the nop
instructions that follow; this will flush the pipeline.
You can choose the "Run Free" option from the "Debug" pull-down menu to allow the your code to run freely, ignoring any breakpoints. The code will continue running until explicitly halted with the "Halt" command.
Note that stopping and restarting execution sometimes confuses the A/D and D/A converters on the six-channel surround-sound board. If this happens, the output will generally go to zero or become completely unrelated to the input signal. This can be fixed by simply resetting the DSP and starting your code from the beginning.
The bar on the left-hand side of the Code Composer Studio window contains shortcuts for many of the commands in the Debug menu.
WAITDATA call and tracing through the program
flow for several iterations of the FIR filter code. What
code does the WAITDATA call correspond to in
the disassembly window?
The DSP boards can behave unexpectedly. If there is no output, try the following (from less to more drastic):
PMST is set to 0xFFE0,
reload the code, reset the DSP, and restart the code.
PMST, reload, reset the DSP
again, and restart your code.
PMST to 0xFFE0, then
reload, reset the DSP, and execute your code.
If problems persist after power-cycling the DSP, ensure that
the DSP board is functioning properly by executing previously
verified code. Do not forget to set the PMST and
to reset the DSP from the Code Composer Studio menu.
If you try all of these steps and still see problems, ask a teaching assistant for help.
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This work is licensed by Douglas L. Jones, Swaroop Appadwedula, Matthew Berry, Mark Haun, Jake Janovetz, Michael Kramer, Dima Moussa, Daniel Sachs, and Brian Wade under a Creative Commons Attribution License (CC-BY 1.0), and is an Open Educational Resource.
Last edited by Adan Galvan on Feb 25, 2004 11:55 am US/Central.
"Doug course at UIUC using the TI C54x DSP has been adopted by many EE, CE and CS depts Worldwide "