Cycle counter on ARM Cortex M4 (or M3)?

Question

I\'m trying to profile a C function (which is called from an interrupt, but I can extract it and profile it elsewhere) on a Cortex M4.

What are the possibilities to

Answer 1

If your part incorporates the CoreSight Embedded Trace Macrocell and you have appropriate trace capable debugger hardware and software then you can profile the code directly. Trace capable debug hardware is of course more expensive, and your board needs to be designed to make the trace port pins available on the debug header. Since these pins are often multiplexed to other functions, that may not always be possible or practical.

Otherwise if your tool-chain includes a cycle-accurate simulator (such as that available in Keil uVision), you can use that to analyse the code timing. The simulator provides debug, trace and profiling features that are generally more powerful and flexible that those available on chip, so even if you do have trace hardware, the simulator may still be the easier solution.