pic16f688 based digital voltmeter

Actually this is the another version of my older DVM project that was based on PIC12F683. The older version displays the measured voltage on a LCD that is driven serially by PIC12F683 using 3 I/O pins. The new one uses PIC16F688 microcontroller that doesn`t require the serial driver as it has got enough pins to drive a LCD directly in 4-bit mode.

The theory and math is just the same. You can read my PIC12F683 version of this project here. Important: You need a regulated +5V supply for accuracy of the output. The ADC uses Vdd as the reference for conversion, and all computations are done with Vdd = 5V. You can get a regulated +5V using a LM7805 linear regulator IC.

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