Frequency Counter

Simple Frequency Counter

Counter schematic.

Connections to LCD module.

This is the support page for the simple frequency counter project in Homebrew, RadCom October 2006. The original design used a gate time of one second which gives a count resolution of 1Hz. Maximum input frequency is about 50MHz. A VHF/UHF prescaler for this counter is described in Homebrew, RadCom February 2008. U2 is a PIC16F628 (PIC16F628-20 or PIC16F628A). The PIC crystal frequency is 10.240MHz. The firmware is easily modified so that a 10MHz crystal can be used instead. Homebrew for March 2008 shows how this counter can be used with a GPS or Loran controlled gate.

PCB artwork for the RadCom frequency counter can be found here:

The original PIC assembly source code for the RadCom Oct 2006 frequency counter is here:

100mS gate time version for use as a frequency display in a receiver/transmitter:

Counter PCB top view.

PCB component overlay.

PCB track pattern.

Updated version 2.1 for RadCom Homebrew Feb. 2008 with gate times of 0.4S, 4.0S, 1.28S and 12.8S
Pic clock frequency = 10.240MHz.

Version 2.1 for 10.000MHz clock. Dec. 2007.

This is a hacked version of the counter firmware which allows the counter gate time to be determined by a 1pps signal from a GPS or Loran receiver. More details in Homebrew, RadCom March 2008.
GPS controlled version measuring the frequency of a 10MHz OCXO using a gate time of 200 seconds.

These display modules have been tested and found to work perfectly with the counter:
Maplin 2x16 display. N27AZ. Samsung chip.
Densitron 2x16 with Oki M6222B chip.
Generic unbranded 2x16 with Hitachi HD44780 chip.
Winstar WH1602A 2x16
L2432 2x24 LCD module.
Powertip PC 1602-F