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Footswitch schematic for SmartSDR for MAC

Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin
edited June 2021 in SmartSDR for Mac

There are many ways to toggle RTS (a level on an RS232 port) so that a foot switch can be made to function on SmartSDR for MAC.

You can use a full FTDI USB/RS232 cable or there these boards available online from eBay or Amazon and many other places like robot shops.

I am using the Gikfun FT232RL 3.3V 5.5V FTDI USB to TTL Serial Adapter Module for Arduino Mini Port and I bought 2 of them for $12 Canadian. I then added some heat shrink and with a printed heat shrink label so I remember what it actually does later in time. :)

The creative types may want to do this and hide it nicely in the footswitch. I might do that with my next version. As well, I am using an inexpensive foot switch I bought off Amazon. Installing this in a footswitch would make a cool-looking USB footswitch.

I have added a 10K pull-up resistor to ensure the level stays high and not floating, which is a good practice and I also added a 0.1uF cap to help with debounce issues.

You could also do this with a hand switch if you wish.




  • Ignacy
    Ignacy Member ✭✭

    Nice idea. Did you use it for CW too?

    I bought the same module but did not add resistor or capacitor. Seems debouncing is crucial as extra dits appear.

    Lots of trouble with installation. With BigSur, the terminal does not have a permission to copy system files. Then, the system file for USB/FTDI looks differently than shown in the SmarSDR for Mac manual.

    Ignacy NO9E

  • Mike-VA3MW
    Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin

    I did not try CW.

    My MAC saw this board immediately and without issue, but it could have been signed via some other reason.

    Sending CW over a LAN technically works, but not functionally as a LAN will lead and lag resulting in some strange sounding CW.


  • markw
    markw Member
    How would this be configured in SmartSDR to sense RTS is pulled low?
  • AA5SH
    AA5SH Member ✭✭

    Have a look in the Tools->CW Keyer Settings: