Maximun Voltage Input Pin 13-18 (ADC1 input)

[fruiz1113]

Even I understood that for ADC measurements you have to enable internal attenuation according to input voltage , for instance 3.3 V , 11db :
adc_c = adc.channel(pin='P16', attn=ADC.ATTN_11DB) ; what happens if I forget to set the attenuation and apply 3V peak at this input port , does it damage ?
If I apply 3.3 V before downloading the script , does it damage ?
Thanks

[robert-hh]

@fruiz1113 All GPIO input including the analog inputs can withstand 3.6V (Vdd + 0.3V). Only the values will overflow. You may go beyond that up to 5V, as long as the inrush current is limited by a sufficiently high impedance, e.g. a resistor >= 4.7 kOhm at 'slow' signal transition.

[fruiz1113]

Hi Robert , thanks for the reply but look the end of this document for adc input :

https://docs.pycom.io/firmwareapi/pycom/machine/adc/

This doesn´t apply to GPY+Expansion Board kit ?

[robert-hh]

@fruiz1113 I looked into the ESP32 data sheet, and it's the ESP32, which is built into the GPY. 3.3V is the safe voltage. The ESP32 data sheet says Vdd + 0.3V, which is 3.6V at a Vdd of 3.3V. But the ESD protection circuit on each pin inside the ESP32 is able to catch overvoltage, as long as the current is limited.
If you expect higher voltages than 3.3v as normal operation, better use an appropriate method for shifting (e.g. voltage divider, or external limiting circuit, ....).

[fruiz1113]

@robert-hh Thanks !