ESP32 Max ISR speed

Advanced Solutions Debugging
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Hi,

Nice to meet you. I am a new entry in this forum, looking for help

I have this setup: D1 mini ESP32 program using PlatformIO and Arduino framework

My goal is run an ISR as fast as possible ( at least >100 000 HZ ) while running the loop task for monitor values from ISR and print data trough serial

Currently I was able to run up to 25 000 HZ, higher rate will crash the MCU

Code here

#include <Arduino.h>


  hw_timer_t * timer3 = NULL;  
  
  volatile long  timerCounter = 0;
  
  volatile float a, b;

  static const uint16_t timir_divider   = 80;//F = 1 000 000
  static const uint64_t timir_max_count = 40;  

  static long tick_5s = 5000000/timir_max_count; 


  void IRAM_ATTR onTimer3() {
  REG_WRITE(GPIO_OUT_W1TC_REG, BIT4);  
  timerCounter++;

    a = a + 0.0000000001f;
    b = b + a;
    if(b > 100000.0f){ 
      a = 0.0f;
      b = 0.0f;
    } 
}

void setup() {
  pinMode(4,OUTPUT);
  REG_WRITE(GPIO_OUT_W1TS_REG, BIT4);  
  delay(500);
  // Initialize Serial Monitor
  Serial.begin(115000);

  timer3 = timerBegin(3, timir_divider, true);  
  timerAttachInterrupt(timer3, &onTimer3, true); 
  timerAlarmWrite(timer3, timir_max_count, true); 
  timerAlarmEnable(timer3);

}


void loop() {
  if(timerCounter > (tick_5s)){ 
    timerCounter = 0;
    Serial.println("cycle");
  }
}