I need to measure a 0-5VDC level with 12-bit accuracy.
Does the A13 board have a built-in analog to digital converter?
There is the mic in, it is connected to the internal audio codec ( it is 24 bit according to the datasheet ).
You can use for ac voltages, but I don't think you can use this input to measure dc voltages ( or at least you have to modify the circuit, this mic input is connected to the A13 via a capacitor C56 and is powered via the network C53-C56,R8-R9 ) and in this case you should verify if its voltage range extends to ground.
So I think you need an external adc ( for example an uext io module )
Be careful as the chip will not tolerate 5V.
Thanks for the UEXT and 3.3V reminder.
I'm kinda old and keep thinking 5V everywhere :)