Frequency Meter

Date of completion: 2008/2012

This was a fairly early attempt of mine to construct and program a reliable frequency meter using a PIC, based on the efforts of others published via the internet. 

Photo

Design

The power supply comes from a 9V mains adapter feeding a 7805 voltage regulator. The PIC is a (nowadays rather ancient) 16F84A and it is is connected to a 16-character LCD display. The input stage design came from the internet and it feeds into a resettable latch constructed from 4 fast TTL NAND gates (74HC132). The PIC is driven by a 20 MHz crystal, enabling highly accurate timing. The code is adapted from that of Barry Smith, who himself adapted it (in 2006) from that of Terry J. Weeder. It does work, but I can't tell you much about the design!

Circuit Diagrams

Tiny CAD (.dsn) file: Frequency Meter 2012

Source code and other files

Freq2012.asm  All files (.zip)