ESP32_FrequencyCounter
test with 'native' code from https://blog.eletrogate.com/esp32-frequencimetro-de-precisao
and
with library from https://github.com/kapraran/FreqCountESP
1st one is more accurate at higher frequencies but needs at least 3 GPIO's
2nd one only needs 1 GPIO and is good for lower frequencies (1Hz .. 10kHz)