That moment when you can’t find your CAT cable (or HOW-TO Program or CAT control your rig with an Arduino!)

… well kind of!

If like me, you have a habit of misplacing CAT cables for rigs, this little tip might come in handy. I’m fairly sure I’m not the first to do it, but I couldn’t find any ready to go instructions or write ups of this being done, so here we go – How to use the USB to serial chip on your Arduino to program or control your rig. (By the Ham that lost his CAT cable, yet again!)

For this I used an Arduino UNO and a Yaesu FT-857, but this should work equally well for any rig that uses TTL level communications and any Arduino that you can access the USB to serial chip by bypassing the microprocessor chip.
Edit: I feel I really ought to reinforce one statement in that last paragraph here – make sure the rig uses TTL level communications, not RS232 – I’m not going to go into the differences here, but if you’re interested, have a look at this. You may end up doing more harm than good if you plug your Arduino into an RS232 com port! Rule of thumb – if the rig has a 9-way D CAT port it’s a good bet it uses RS232 – DO YOUR RESEARCH!

There are 3 documented ways to leverage the power of the FTDI USB to serial chip on an Arduino UNO.

  • Remove the AT328P chip.


  • Connect the RESET pin to GND.


  • Upload this simple sketch …
void setup(){
void loop(){

I opted for the second option.


The RESET pin is connected to GND by the white jumper. The yellow jumper is also GND, the red jumper is connected to the RX pin and the green jumper to the TX pin on the Arduino.

As an example, here’s the FT-857’s ACC port which I used for the test. Incidentally the ACC port is the same on the FT-817 and the FT-897 so this should also work on those radios …


And here’s the schematics for a few Kenwood radios …


The three pins we’re interested in are GND, TX D and RX D – they should sound familiar!

Connect GND on the Arduino to GND on the radio.

Connect TX on the Arduino to RX D on the radio.

Connect RX on the Arduino to TX D on the radio.

After checking all your setting in whatever software you are using (port, baud rate, the usual sort of thing!) fire it up and see if it works! It *should* work as if you were using a OEM CAT lead bought for £60 or so or a chinese £15 job off eBay!

3 thoughts on “That moment when you can’t find your CAT cable (or HOW-TO Program or CAT control your rig with an Arduino!)

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