ESP32 & PIO debug - cpu time

ghz2000 · January 31, 2020, 6:05am

I am doing PIO debug using ESP32 devmodule and FT2232H minimodule.

I want to know the CPU time to measure the processing time of the function.

How can I check the number of CPU cycles?

maxgerhardt · January 31, 2020, 12:39pm

You don’t even need a debugger tool to see this, just read the number of cycles (CCOUNT / clock count register) using the intrinsic XTensa CPU functions before and after the function execution. This was already answered in Function for reading cycle count of CPU clock - ESP32 Forum, see the function

github.com

espressif/esp-idf/blob/4480ab6c8ce70778df4948e587e712540de237eb/components/esp32/include/xtensa/hal.h#L724


      
          
          
/*----------------------------------------------------------------------
             				Core Counter
            ----------------------------------------------------------------------*/
          
          
/* counter info */
          extern const unsigned char Xthal_have_ccount;	/* set if CCOUNT register present */
          extern const unsigned char Xthal_num_ccompare;	/* number of CCOMPAREn registers */
          
          
/* get CCOUNT register (if not present return 0) */
          extern unsigned xthal_get_ccount(void);
          
          
/* set and get CCOMPAREn registers (if not present, get returns 0) */
          extern void     xthal_set_ccompare(int, unsigned);
          extern unsigned xthal_get_ccompare(int);
          
          

          
/*----------------------------------------------------------------------
                                       Miscellaneous
            ----------------------------------------------------------------------*/

or for Arduino

github.com

espressif/arduino-esp32/blob/7fe2812f7f619404f8b0fd428f9a6b28b7f9c3f6/cores/esp32/Esp.h#L104-L109


      
          uint32_t IRAM_ATTR EspClass::getCycleCount()
          {
              uint32_t ccount;
              __asm__ __volatile__("esync; rsr %0,ccount":"=a" (ccount));
              return ccount;
          }

I.e. just call

uint32_t cyclesNow = ESP.getCycleCount();

maxgerhardt · January 31, 2020, 12:43pm

If you’re looking for a more in-depth JTAG tracing of the CPU core instead of explicitly putting in the code, then, as the ESP-IDF documentation says, use external tools like SEGGER SystemView (Application Level Tracing library - ESP32 - — ESP-IDF Programming Guide latest documentation).