‘CAT-to-BCD’ Band Data Converter for Kenwood TS-590, with Arduino Nano

yu2zz / July 11, 2023

The Nano running this program communicates with the CAT interface in the Kenwood TS-590SG, reads the current frequency (band) data three times a second and outputs it in the standard Yaesu BCD format at its pins 12, 11, 10, 9 (A, B, C, D, respectively). It should also work with the TS-890.

The Arduino Nano is connected to the radio through a TTL-RS232 converter.
EDIT, March 2026: The picture was updated for purely aesthetic reasons, keeping all electrical connections unchanged.

The Nano is encased in heat-shrink tubing, along with a tiny TTL-RS232 converter from AliExpress . It will not win any beauty contests, but all of this will be hidden behind the radio anyway. The two-wire USB cable supplies +5V to the Nano (from the PC or from any other +5V source).

The other end of this cable is connected to the Nano, i.e. to its pins 12, 11, 10, 9, through four resistors (220…680 Ω, at the pins). This end, shown in the picture, will typically go into a linear amplifier or an automatic antenna switch compatible with the Yaesu/Elecraft band data format.

P.S.
This Nano thing was actually just a quick and dirty spin-off project, using whole chunks of the original program. So the code is not pretty, but it works well.
It all started with this:
https://yu2zz.com/2023/03/21/automatic-antenna-switch-controller-for-kenwood-and-yaesu-with-arduino/

Furthermore, this device
https://yu2zz.com/2023/03/21/cat-to-bcd/
uses practically the same program functions to communicate with the CAT interface and to switch bands automatically. It has been in use for a couple of years already, with no issues whatsoever.

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