ESP32-C6-EVB: ADC on UEXT pins 3 and 4 ?

[boris]

Hey,

Can UEXT pins 3 and 4 (GPIO4 and GPIO5) on a ESP32-C6-EVB board be used to read analog inputs?

I looked at the board's schematics and see there are resistors between VCC and GND wired to those pins (R9&R10 and R16&R18 - both are in a boxed text mentioning "straping pin", and no mention of the resistors' values); so I'm not sure if ADC can be used as-is without modifying anything - eg. unsoldering those resistors.

Thanks!

[LubOlimex]

Why not just use the opto-isolated inputs for DC voltage up to 30V? GPIO1, GPIO2, GPIO3, GPIO5? Or you need more than 4 analog inputs?

R9 and R10 are not placed. They are marked as NA/R0402. NA means "Not Assembled", and R0402 is the size of the resistor. So GPIO5 can be used for ADC. Notice that it is 3.3V ADC, if your signal is bigger you need to lower it down.

[boris]

oooh I had no idea I could use the opto-isolated inputs for ADC! For some reason I thought they'd act like digital inputs - ie. voltage present = 1, no voltage = 0; (I never had a board with opto-isolated inputs before).

Thank you!