Hi All,
I want to measure the Grid voltage in microcontroller and for this purpose I am using opto coupler for isolation and output of opto coupler will be based on input current. following is the circuit
I am using real hardware not proteus for results. also I am using pic18f452 microcontroller and MPLAB for programming
I am getting some results but they are not accurate. following is the chart where I showed the grid voltage "
column C" and voltage at uC pin "
column D" after optocoupler output. "
Column F" is the ADC value which I am getting.
Then divide this ADC value with scaling factor 2.91 to get real voltage value "
column H".
"
column G" shows the voltage if we apply formula on "
column F" that is Vout = (ADC value *5)/1023, it means voltage at ADC pin and voltage calculated in microcontroller are different. What is the cause of this? Am I missing something here?
Also "
Column J" shows the actual ADC value according to the "
Column D" value. after multiply "
column J" value with scaling factor 2.91 I am getting "
column K" values.
Hope you guys understand what I am trying to convey.
Need your suggestions to improve the accuracy of this