NMEA Converter for Kenwood TH-D7
This is a small microcontroller project that converts nmea data from gps to Kenwood TH-D7 HT.
Kenwood TH-D7 is a FM dual bander with built-in tnc and aprs options. It has external GPS connection to receive position data from gps
and send it over aprs net. Unfortunately, there is bug on the tranceivers firmware.
When I am doing a research over it, i found this site that explains the problem:
http://www.webalice.it/hotwater/Potator.htm
Tranceiver only accepts old version of NMEA but my gps is new !
I tought that PIC 16F628 is too 'big' for this job, so i decided to use small 8 pin mcu and selected PIC12F675.
I wrote a very very noob code and tested it, after some corrections it worked.
It basically waits for $GPRMC sentence, takes specific datas, calculates checksum and sends them in right format.
A made a small Black Box a few years ago. There is a gps and a tinytrak circuit in it but I can also get a serial gps data from it.
I decided to keep my Kenwood HT intact and put this chip in to this black box. There is also a 10MHz xtal in it, so there is no need to use a second xtal.
I took and bend the pins of pic, put a 100n smd capacitor on supply line*, clock* input wire*,
data input* and data output* connections.
right click and choose "save target as":
C Source Code
HEX File