[aprssig] Kenwood D710 Mic protocol

John Gorkos jgorkos at gmail.com
Fri Nov 11 14:51:47 CST 2011

On 11/10/2011 10:57 AM, Tom Hayward wrote:
> On Thu, Nov 10, 2011 at 07:19, John Gorkos<jgorkos at gmail.com>  wrote:
>> My thought is to build a simple microcontroller that sits in-line with My
>> D710 mic cable.  It could draw off the 8V line on that connector, and have a
>> bluetooth transceiver in it and a pic or avr chip that generates the
>> appropriate 'serial' protocol to simulate mic keypad presses.  By doing
>> that, I could use this handy little wireless, full function keyboard for
>> APRS text messaging.  Normal keypad presses would be passed through from the
>> mic, but any keypad presses sent over bluetooth would be translated from the
>> character sent to the appropriate serial protocol for the mic (including
>> multiple presses, if necessary, i.e. you have to hit '2' three times to
>> generate a "C".
>> Anyway, I was wondering if there are any published specs on the protocol
>> that the Kenwood mic uses to talk to the D710.  According to the "TM-D710
>> Instruction Manual" page 15, pin 8 is "keypad serial data."
> You're not the first one to have this idea. This guy has a working
> prototype of a keyboard adapter:
> http://www.shaneburrell.com/?tag=tm-d710a
> It uses an FPGA to generate the mic key signals, because it's a very
> odd protocol no one has been able to implement with just a
> microcontroller. This page shows what the protocol looks like:
> http://www.coastalchip.com/D710.htm
> I started a similar project, but to simplify things I planned to
> inject serial data on the control head line, because the protocol is a
> lot simpler. It's just TTL UART @ 57600 baud (same as many of the
> other Kenwood radios). I only got as far as investigating the
> protocol, no working prototype.
> Tom KD7LXL
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Well.  So much for that idea.  I knew I wasn't that smart.  Back to 
pounding out messages 12 keys at a time.
Thanks for enlightening me/bursting my little mental bubble.

John Gorkos

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