30 volts panel volt meter using pic mcu

Posted on Feb 7, 2014

This is a simple application of internal 10-bit ADC(analogto digital converter) of PIC16F676 microcontroller. you can use this circuit to measure up to 30 v dc. the possible applications are on bench top power supply or as a panel meter invarioussystem. MICROCHIP`S PIC16F676 is the heart and brain of this circuit. the internal adc of the mcu

30 volts panel volt meter using pic mcu
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with a resistor network voltage divider is used to measure the input voltage. then 3 digest of comm anode 7 segment display is used to display finalconverted voltage. as you can see in the schematic the displays are multiplexed with each other. means we switch on one display and put the corresponding digit on this while other two displays are off this cycle go for each of thedisplay. you can find more about driving multiplexed 7 segment led display from a pic mcu in application note from microchip AN557Four Channel Digital Voltmeter with Display and Keyboard as you can seen in the schematic the 47k resistor and 10 ktrim pot is connected ias a voltage divider configuration. we all know very well that by default pic micro controller ADCreferencevoltage is set to vcc(+5v in this case). sowhatwe have to do is make such voltage divider that can divide out maximum range 30 volts to 5 volts. so we need is Vin/6 => 30/6 =5v voltagedivider. and to keep as less as possible attenuation on the under test voltage we have to keep the voltagedivider resistor value in fewthousand ohms because it takes very little current from the target but asmuch to drive adc of pic.

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