I have a prototype pcb wit a 16F1938 on with Code written in V7 which was now working for 3 months in a vehicle with no issues
We then made now a new pcb with production intend however there is a problem it seems the ADC at AN3 is drawing to much current and pulling the signal level down .
The ADC on AN0,AN1 AN2 is working correctly
![Shocked :shock:](./images/smilies/icon_eek.gif)
(1) with out the micro on the pcb the signal level is correct( loading the signal with 2mA level still correct which should be sufficient for an ADC pin)
(2) with the micro on the pcb and the AN 3 set ad digital input the signal level is also correct (there is no pcb or circuit errors)
(3) programming the micro with the exsisting code(which is running on proto 1 the signal level drops down to 0.5V from 2.10V ,the 2.1 is the correct level of the signal.(the ADC pin must be draing more that 5mA).Pin IS_IN is the output from an gain amplifier to AN3 which measure the current in a watervalve circuit
I am not sure what is casuing this it seems that the ANSEL registers is not set properly (as the AN3 can also be the Vref pin) the strange thing is that it is the same code .??
any hints idea's tot track this down will help me out
![Very Happy :D](./images/smilies/icon_biggrin.gif)