The three boards are connected together via a short
16-conductor ribbon cable that contains the 74F579 data
bus and selection and control signals. The microprocessor
board also contains a 16-conductor ribbon cable
connector for the front panel display and
controls. The boards each measure 7 inches
x 1-7/8 inches. When mounted with the long
sides adjacent, the total footprint of the
counter electronics is about 7 inches by 6
inches. The unit uses about one ampere of
five volts for the digital circuits and less than
. 5 amperes at 24 volts for the piezo
oscillator. Most dual 5/24 volt power
supplies will work.
Figure 9 shows the main component
layout. The footprint is approximately 8
inches x 10-1/5 inches. I purchased all of the
parts through either Jameco or eBay. The
digital components cost less than $30, and
the oscillator and power supply cost a total
of $55.
For software development, I chose the
mikroC Pro compiler and a cheap PICkit 2 to
program the microcontroller. The software
design does not use interrupts and can easily be
programmed in assembly language or BASIC, as long as
floating point arithmetic is available. Now, go get your
“freq” on! NV
28 March 2015
■ FIGURE 9. Frequency counter assembly.
YEARS
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