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Author Topic: How do I sample a -2 V to +2 V analog signal with a PIC microcontroller?  (Read 1873 times)

kynix

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I am using a PIC micro http://www.kynix.com/Detail/1317443/PIC16C711-04%2FP.html with a 10bit ADC to take readings from an analog signal with a frequency less than 300 hz. However that analog signal is in the range of -2 V and +2 V. How can I condition the signal to get it into a usable range (assuming the input to the ADC has to be positive) Also I do not have a positive and negative power supply.

kyrk.5

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Hi

You need to shift the input voltage from the range -2...2V into the range of the ADC which I suppose is 0...5V or so. Google this: voltage adder resistor network
http://www.daycounter.com/Calculators/Voltage-Summer/Voltage-Summer-Calculator.phtml

Are you sure that you are using a 16C711 PIC? I mean it is a C, then usually it is only one time programmable. One time programmable uC-s are not suitable for development. Consider to change a F type.
According to microchip page:
PIC16C711
Not Recommended for new designs
Please consider this device PIC16F716

So do not use this, you will need a lot of them to develop code.

I think 20 years ago was the last time I used one time programmable uC. I also had windowed one which could be erased with UV light. Huhh... 1 minute less in the UV eraser, and it was fun to realise that it was only partly erased :)