#include "esp32-hal-cpu.h"

void setup() {
setCpuFrequencyMhz(240);
}

void loop() {
//function takes the following frequencies as valid values:
//  240, 160, 80    <<< For all XTAL types
//  40, 20, 10      <<< For 40MHz XTAL
//  26, 13          <<< For 26MHz XTAL
//  24, 12          <<< For 24MHz XTAL

  Serial.println(getCpuFrequencyMhz());
  Serial.println(getXtalFrequencyMhz());
  Serial.println(getApbFrequency());
}