Frequency meter with Prescaler

Here is a modification to allow a "divide by 64" prescaler to be used with the "new" frequency meter.

Pin 18 of the PIC is now used to select between direct readout (without prescaler) and "multiply by 64" (with prescaler).

To select direct readout, connect pin 18 to ground.

To select "multiply by 64", connect pin 18 to 5 volt.

The measuring period is 1 second (not auto-ranging ;-).

There are two versions of the hex code:

• prehex1
• prehex2

I don't know which will suit your display. You may have to try both.

The source code is hiding behind this link.

If you have a /20 prescaler, then this version of the source code is for you.

Serial 9600 baud output is available at pin 17. You will need to add a TTL to RS232 level converter. A MAX232 chip works fine.