Chipu
Posts: 2
Joined: Mon Feb 26, 2018 4:58 pm

Raspberry pi Pico voltmeter

Sat Jan 23, 2021 12:05 pm

Hi,
I want to be able to measure the voltage of a 12v battery and display the voltage onto a 16x2 LCD screen. I was originally going to use an Arduino Nano, however with the new release of the Pi Pico with analogue inputs, I was wondering if I could use that instead. unfortunately, I have been unable to find the maximum input voltage on the Pico's analogue pins. So my question is, what is the maximum rated input voltage on the input analogue pins?

Thanks

hippy
Posts: 9159
Joined: Fri Sep 09, 2011 10:34 pm
Location: UK

Re: Raspberry pi Pico voltmeter

Sat Jan 23, 2021 3:50 pm

Page 625 of the RP2040 datasheet -

ADC Input Voltage Range : 0V min, ADC_AVDD max

Page 626 -

ADC_AVDD : 1.62V min, 3.3V typ, 3.63V max

Page 174 -

ADC_AVDD supplies the chip’s Analogue to Digital Converter (ADC). It can be powered at a nominal voltage between 1.8V and 3.3V, but the performance of the ADC will be compromised at voltages below 2.97V. To reduce the number of external power supplies, ADC_AVDD can use from the same power source as the digital IO supply (IOVDD) - The voltage on the ADC analogue inputs must not exceed IOVDD

jonincanada
Posts: 1
Joined: Sun Jul 21, 2013 2:21 pm

Re: Raspberry pi Pico voltmeter

Tue Jan 26, 2021 3:13 am

Battery voltage monitoring will no doubt be a common application. I'm giving the pico a shot as well to measure my raw drone battery voltage and pipe it through the UART port. There's a nice github write up for the regular pi here for battery management:
https://github.com/aboudou/picheckvoltage

But seems like using a voltage divider in the 10k range is the simplest approach. But yeah, standard range for ADC seems to be 0-3.3v. Just leave some room since a charging 12v lead acid can approach 15v.

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