Digital Volt Meter using PIC Microcontroller

Volt meter using PIC controller project is the application of built-in ADC of PIC microcontroller. In which I discus one example of attenuator for 100v range. If anyone understand this example he can design for more ranges. There are some learning points for learners.

1.       How to Program ADC

2.       How to set voltage ratio for ADC input

3.       How to adjust attenuator for voltmeter

4.       Interfacing of LCD

5.       Reading values of ADC

6.       How to use built-in libraries of MikroC Pro for PIC

Here is the list of components

1.       PIC16F877A

2.       Crystal 10MHz

3.       Non pol capacitors 33pf

4.       Resistors

5.       LCD 16x2

Little math for attenuator

Range for 100v

ADC max input voltage 5v

So set the attenuator which drop 95v when input max at 100v

So 100/5 = 20 so the 19:1 is the best ratio for this division

So simply I set attenuator resistor R4 19k ohm and input resistor R2 1k ohm

Then see the code

Circuit diagram: 

MikroC code:

Little explanation required for it

I want to show reading from 0v to 100v and ADC input is 5V max so what is scaling voltage value for display digits = 5v/range

Scaling voltage = 5/100 = 0.05 means 50mv

It means that when 50mv appear at ADC then must display 1v at LCD.

And another thing in ADC into the microcontroller that is

ADC length is 10bit output so what is mini voltage value at which ADC change one step output in binary like from 0000000000 to 0000000001

= 5/2¹⁰

5/1024= 0.00488 means 4.8mv

But I want to display 1v at 50mv now fine the factor to divide ADC output

=50mv/4.9mv = 10.2

So here is very important we will divide ADC value with factor 10.2 now see