MSP430 Timing Analysis

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Howdy, everyone.

I have a C program written for the MSP430.  The program is basically
just an infinite loop, with different sections within the loop:

while(1) {
  /* section 1 */
  /* section 2 */

The various sections have some 'if' and 'else' statements, so they
take different amounts of time from iteration to iteration. Is there
any convenient mechanism to determine how long these various sections
take?  Even an average/mean time would work (although a probability
distribution function would be best).

Earlier, I resorted to using the actual MSP430 hardware to run a
million iterations of each individual section, and  used a handheld
stopwatch to time it (I had it turn an LED off when it finished).
This was a pain, and now I don't actually have the hardware anymore.
So, I'm hoping for a software simulation tool.

Any help will be greatly appreciated.

Re: MSP430 Timing Analysis
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There are two basic approaches: simulation and realtime measurement.

You can use a simulator to get a very accurate measurement of the
execution time, but this doesn't work well if you need to use realtime
inputs for the code.  It works well for situations where you can feed in
a small set of typical data and time the processing.

For realtime measurement, I would drive an output once per cycle or
during routine execution, then look at it on a digital scope.  With the
HP Megazoom, you can capture a wealth of information in a single
snapshot, then blow it up and look at the timing.

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The IAR package simulator will do this.  If you program in assembly you
can use the free kickstart version.  You can use it determine the number
of elapsed cycles up to the breakpoint that stops the execution.


Re: MSP430 Timing Analysis
You can always examine the code and figure out the cycle counts,
although there are traps for the unwary with the MSP430 due to its
emulated instrctions and constant generators.

The other simple method is to use the internal timers. Use the fastest
stable clock frequency, for example I use 8MHz MCLK and run Timer B at
8MHz. Allocate a variable for counting timer overflows and a second for
counting passes through the loop. before entering the loop Move TBR to
START_TIME, and clear OVERFLOW_COUNT. Enable the Timer B overflow
interrupt and count overflow events. At the start of each loop increment
LOOP_COUNTER. When you've executed enough passes you can simply average
the time. Alternatively you can start and stop the time at the beginning
and end of the loop, and accumulate differences with a moving average


Chess Saurus wrote:

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