16F886 and Voltage reference

[Acetronics2]

Hi, Peter

may we understand your board design is already done and can't be altered ?

If so ... see Hendrik's answer.

another solution could be, if your board current draw is quite constant, to add a little calibration routine in your program : @ first power up, you use a known reference voltage on one ADC pin ... then the routine calculates a correction coeff to use in your ADC measurements ...

say, IF the EEPROM cal value is $FF or $ FFFF ( generally is with newly programmed components ) , THEN you enter the cal. routine @ power-up ...

Alain