Would like to add some sort of Auto calibration to the system if possible, to iron out any variation is resistor tolerances across different PCB boards. The PIC I am using has some on-chip EEPROM memory. I was thinking of something on the lines of, at first power up, as part of the manufacturing process, the board is connected to a known set voltage (lets say 90.0 volts for example) and the firmware calculates the required divison/multiplication to get the display to read bang on 90.0 Volts. Any suggestions would be very appreciated.

Mark in Spain.