Pulsed voltage reading with PIC?

[seyyah]

How can i read a pulsed voltage(PWM) which can be positive or negative, by pic's adc?
What kind of circiut must i use before inputting to the adc? Filter, opamp circuit for biasing etc? Also what must i do to calculate the rms value of the voltage? Should i read mean values at certain times over a period and then calculate? How's this job done conventionally?

 

[bobcat1]

Hi
If your signal is goinig to negative rail you must clemp it to the ground potential

using diode otherwise it might damage your input stage


All the best

Bobi

 

[seyyah]

I made it by adding offset to the opamp.

 

[metal]

Hello

you may also use a clamping circuit based on diodes and capacitors.

Regards

 

[seyyah]

There is some problem with clamping circuit. If i use it in high voltage side then voltage goes very high and exceeds the limit if i use it low voltage side than the voltage drop on diode worsen the measurement and drops accuracy.