The BBRC Frequency Counter (2009)

NB This page refers to a 2009 club construction project and is provided for information only.

Components may no longer be available.

Software mentioned may not still be available.

Also the data files may not be compatible with current versions of the software.

NNB This information was originally hosted on a now-deceased external website. It has been reconstituted from a variety of sources and we cannot be certain it is error-free.


Viewable PDF Downloads
If you only need to refer to the project’s schematic or PCB layout, they are provided as PDF documents in the zip file below.

Modifying The Schematic or PCB
The project schematic and circuit board were designed by Jeremy G8MLK using Express PCB. The current version of the software is available here Once installed, you may be able to open and change the project files. If not you may need to find an older version of Express PCB.

The schematic is provided in pdf and sch file formats in the zip file below.


The software was developed with Microchip’s MPLab IDE. The current version can be downloaded here: Once downloaded and installed the zip file below which contains a seperate ‘MPlab files’ zip file with the source files for the project. Unzip this zip folder them to a new directory. Then start MPLab and from the file menu select ‘open workspace’. Select the only workspace file in the package you just unzipped.

You might like to start by looking at the file ‘code explanation.txt’ which is a brief description of what is happening in the code where. Turning line numbers on (from edit -> properties->ASM file types (tab) in the old version of MPLab) will help here.

If you are going to change the code at all then the data sheet for the PIC 16F628 used is invaluable. To ensure you get the latest version, download it from the Microchip web site where you got MPLab from above – it’s in the same ‘design’ section of the site under datasheets. Note the 16F628 is a 8 bit device.

Once you have successfully build your version of the code, you’ll need to transfer it to the board. This is done with another piece of hardware, a programmer. Commercial versions are available from RS, Farnell and the usual online marketplaces. NB you will need to check the programmer supports the 16F628.

Note that the ICSP pin out on the board is non standard so you may have to make up a special cable to go from your programmer to the board. As a club member, there was a programmer you could borrow as part of the club’s loanable kit. We’re not currently clear whether this still exists.

The zip files below were checked out with VirusTotal Nov 2023.

BBRC DFM 2.4 contains all the project files, including a separate zip file with some frequency meter software source files. This zip file does not contain ‘code explanation.txt’.

BBRC 1-22 contains the original software source files and does include ‘code explanation.txt’.

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