Impc001 adc errors


#1

I am using adc pins on new impc001 breakout board and seeing some erratic readings on imp central. I am using short unshielded wires (100mm) to external low impedance sources.

The adc counts can vary by a few thousand counts each reading at 30 secs intervals,
This sounds very high and just wondering do I need some buffering and filtering of adc inputs to improve the readings.


#2

Adding a capacitor to the input (eg 100nF) is certainly worthwhile as the ADCs are muxed and so you get charge injection as the input is selected. Try that?


#3

Ok thanks Hugo.
That certainly made a big improvement by adding those caps on breakout board.

Just wonder do I need to convert the 16bit ADC readings using read command down to 12 bit and how do I do this if needed ?


#4

You can do that just by shifting right 4: new = (old >> 4)

We report as 16 bits as this allows newer devices with more accurate ADCs to be used seamlessly.