Anyone done: Kiwi USB port => USB-to-serial adapter => serial => CAT/hamlib device ?

I know there are projects/products that control the Kiwi from CAT-related devices using various means (e.g. SuperSDR, CATSync, KiwiSDR Monitor et al).

Based on a user request I'm interested in the opposite direction: anyone who has made a Kiwi extension or custom change that sends a CAT (or simple string) over a serial connection to an external device when the Kiwi frequency/mode changes. Preferably using a USB-to-serial adapter#

Has anyone done this? There is of course support for the various antenna switch extension devices, but I'm interested if anyone has done a more generic solution, CAT-related or not.


# Note that a Keyspan USA-19H adapter will work with no software install required on the current Debian-8 Kiwi distro. There's even an existing Kiwi shell alias called bbser that uses the screen program to connect at 115.2k baud.


  • Hi John,

    That's an interesting idea, and one that opens up even more possibilities, and the associated development and support issues :-(

    On one KiWi site in the UK (Weston ) , we are currently polling the /status url with MQTT in order to switch in various notch filters as required when propagtion conditions vary (typically day / night), but something like what you are describing, perhaps with enhancements, would maybe better lend itself to the control of other local equipment.

    CAT driven Transmit / Receive switching & sdr muting with an on screen message would be another application I could immediately think of.

    Definitely worthy of further consideration.



  • The application from the user request is output of the current tuned frequency. So for example an external loop tuner could track the Kiwi. I have this working.

    BUT, it looks like it's all for nothing. Whoever wrote the serial/USB driver does busy waiting of some sort which destroys the Kiwi realtime requirements. You get audio and waterfall glitches anytime USB serial data is being sent. I know this because the problem is MUCH worse at low baud rates. The situation is just barely tolerable at 115.2k baud. And with outputting the bare minimum of characters (CAT-compatible "FA" string).

    I've tried all the usual tricks to mitigate this. Nothing helps.

  • Hi John,

    That's a pity.

    However I was thinking about this last night and although there are advantages in terms of simplicity in using a locally connected RS-232 port, it would also bring about it's own problems in terms of noise and physical connection issues.


    What about using a cheap (~ £25 GBP) Ethernet to RS-232 server ?

    Something like this

    The manual can also be downloaded from the webpage

    The ability to distance the CAT interface from the KiWi could be useful, but it's a pity that it doesn't also provide some form of GPIO interface that it could be used for antenna switching too, but you can't have everything.

    However, I did notice that it also has an RS-422/485 interface, and the thought crossed my mind it could be used to drive a PTZ IP video camera (we intend to put one up our mast on a web sdr site that has a spectacular view of the coastline). Then the KiWi header could maybe show the live webcam feed and a basic PTZ control interface :-)

    But I digress...

    This was initially just an idea of how the CAT function could be implemented by other means, but there are other options, such as maybe using a Pi Zero or ESP8266 with RS-232 converter ?

    This could open up a whole new can of worms, oops, I meant to say 'range of possibilities'.



  • Beaglebone green is already has a serial port on board. No needed USB-to-serial# adapters.

  • Ah,

    The Serial Debug port, I forgot about that :-( Good spot.

    I assume it would need a cheap interface board to provide 'genuine' RS232 levels and / or 5v open collector TX/RX for CIV / CAT interfaces.



  • Beaglebone green is already has a serial port on board. No needed USB-to-serial# adapters.

    Not useable or easily useable.

    The P9-21,22 pins used for UART-2 on the Grove J5 connector are already used by the SPI interface between the BBG and the Kiwi board.

    UART-0 on the J0 header is opened by U-boot and Linux as the console. You'd have to figure out how to disable that or not conflict with it.

    It might be possible to use UART-4 on P9-11,13 or UART-1 on P9-24,26 (the Kiwi's current use of P9-24 as the audio interrupt would have to be moved to another P9 pin). This is possible because those P9 pins are brought to the top side of the Kiwi board and you could possibly solder wires onto the top of the header pins.

    The USB/serial adapter was nice because you didn't have to do any of that. Not even install any software drivers.

    But all of this is essentially moot. You don't know if the Linux serial driver has Kiwi realtime issues itself. AND I'm not supporting any sort of general CAT interface anyway.

  • edited August 2022

    @jks, thanks for the detailed description of GPIO. I have not studied this in detail. Just assumed to use a Beaglebone hardware UART.

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