Slow ADC on ESP32

[tosmaz]

Why does simple ADC.read() take ~300uS? It seems very slow if we are speaking about 200kSps ADC. Is there any hack to make it faster?

[bixb922]

With @micropython.native and this code, I get about 43 microseconds per sample

    read = adc.read_u16
    for i in range(len(signal)):
        signal[i] = read()

[bixb922]

With machine.freq(240_000_000) and @micropython.native time gets a bit lowe

[jimmo]

On stm32 we have adc.read_timed and adc.read_timed_multi, which might be worth implementing on other ports like ESP32. https://docs.micropython.org/en/latest/library/pyb.ADC.html?highlight=read_timed#pyb.ADC.read_timed

[robert-hh]

This is implemented in a PR for SAMD as well, but still in the queue, maybe a loooong time.