DSPIC33EP128GM306 analog input channel value dependent from other channels
In one of my applications I need to read several analog inputs. Since 12bits are enough for me, I've decided to use directly DSPIC's analog input pins.
For every analogue input pin there is a buffer with a serier resistance of 120 Ohm.
I've noticed that some input channels changes if I change other channels voltage.
For example, I've a fixed input voltage in channel 3 which converted is 1200 (on 4096 total bits). If I change voltage on channel 2 from 0 bits to 4096 the value on channel 3 changes to 1240. there is a dependace o almost 1% from a channel to another.
I don't notice this dependance to all of the channels, it depends from channel to channel.
Has everybody ever noticed this problem?
Thank you in advance,