Hi LinkMTech,
thanks for your help. I will try it out, but if you can provide me the simple schematic or guidance to setup the op-amps without offsetting the voltage, that will be good. I'm not familiar with the op-amps... Thanks again.


Another problem i'm facing now is the ADC to measure some small voltage drop in the low ohmic resistor (for current sensing).

A low ohmic resistor will be connected serially with the 13.8V on the left and a Load (RL) on the other end. When in operation mode, some voltage dropped (Vi) in the low ohmic resistor and the ADC will pickup Vi and convert into the current reading. The question are:

1. How do i setup the ADC to measure the Vi. The source is 13.8V, but pic is powered by 5V in my design.

2. The PIC is configured in VREF+ = AVDD, VREF- = AVSS to measure others voltage reading, what do i need to change for the VREF in order to measure Vi.

Thanks! Really appreciate your help.

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