I am working with a small ADC project in circuitpython on a XIAO RP2040 and I want to use an external 3V VREF - there is a pin on the Raspberry Pi Pico marked external VREF - is this available in the XIAO RP2040. Can anyone provide hints on how to do this?
Thanks
How about reading that 3.0V reference voltage with an analog input pin and scaling other analog inputs accordingly?
Thanks Adrian - in order for the ADC to work it is using a VREF and scaling the measurements 0 bits at ground up to 12 bits at VREF: my guess is that it is using 3.3V input power - this is what the pico does and it is noisy but it improves if you add an external VREF - they suggest an LM4040 3V. I’m new to circuitpython and micropython so there could be a way to direct VREF to a pin in the board module but I’ve not seen any example - and nothing I’ve found shows a pin on the XIAO RP2040 labelled as ex_vref so perhaps I’m out of luck. There are 4 ADC channels so I should be able to make it work measuring the ground in one channel the reference in another and the two measurements of interest on the other two.
Thanks again