Would you like automatic entry of frequency and mode data to your logging computer even from a rig that's
not computer controllable? I have modified the software for Neil Heckt's PIC-based frequency display¹ to pro-
vide a serial data port. All you need to do is replace the PIC16C71 chip with my modified version² and connect
it to your computer via a TTL-to-EIA-232 level converter.

    The data port is RB6, pin 12 on the PIC16C71 (see Figure 2, following page). This pin was formerly used
for the ZERO switch,Sl. With the new software, when Sl is closed the counter performs as before; that is, it will
count and display. When Sl is open, the counter halts and waits for a serial command. The command can be
any character; the software only looks for start and stop bits. On receipt of a command, the counter counts and
displays the result, then transmits it to the computer. If the computer sends a command repeatedly, as most
logging programs do in automatic mode, the display will be updated regularly. Otherwise, it will display the
frequency and mode at the time of the last command or Sl closure. I inserted a 220 ft resistor between Sl and
ground to protect the chip if Sl is closed while it is transmitting.

    Ideally, the counter should be connected to the local oscillator and MODE switch of your rig, but I have
used it with an antenna to pick up transmitted RF. I have also linked it to my transmission line via a toroidal
transformer. The disadvantages of this method are that you must press the logging key while you are
actually transmitting and no mode data is available.—
Dave McClafferty, VE1ADH, 28 Balsam Cir, Lower Sackville, NS B4C 1A9, Canada

¹ N. Heckt "A PIC-Based Digital Frequency Display," OST, May 1997, pp 36-38.

² I supply programmed chips for $25 US, contact me by e-mail: at060@chebucto.ns.ca by "snail mail "at
the address shown on the hint or by telephone at 902-864-0268. Please specify the data rate, 1200 to 9600.
1 will send the .HEX file via e-mail to anyone wanting to burn their own chip.

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