ADC problem

[georgestheking]

The PICO is buggy and has limitation following PICO HARDWARE DATASHEET. One idea will be to use an external ADC like the MCP3204.

Best regards

Georges

[redoxcode]

Can you elaborate on how 'the PICO is buggy'?

[georgestheking]

Hi, A small problem for the ADC : https://www.hackster.io/news/raspberry-pi-confirms-it-is-investigating-a-flaw-in-the-raspberry-pi-pico-rp2040-adc-95c393b55dfb

Best regards Georges

Le mer. 11 janv. 2023 à 22:04, redoxcode @.***> a écrit :

Can you elaborate on how 'the PICO is buggy'?

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[redoxcode]

I am not sure if I understand this correctly, but from my calculations the ADC makes an error of +- 5.64 mV (measuring 0-3.3V) at it's worst. So if the EuroPi hardware would map 10V to that range in a perfect way, that would be +- 17.09 mV. I would not say it makes the PICO buggy. It just isn't able to reach it's full potential. But since the behavior is systematic and understood there should be ways to compensate for that at least partially, if needed. I think the PICOs ADC with the bug compares to a 11.99 bit ADC. So an external 12 bit ADC isn't that much of an improvement for a lot of added hardware complexity.

[roryjamesallen]

I understand the limitations with the inbuilt ADC of the Pico, but it is really too late to fix this now with the current hardware! Future hardware will almost certainly have external ADCs to allow there to be more of them as well, so I'll mark this as closed but know that it's on the list for future hardware improvements!