Writing New Firmware For A Handheld Radio


When playing around with a cheap, handheld, dual-band radio, [Lior], a.k.a. [KK6BWA], found a schematic for a similar and even cheaper radio. He realized the programming pads were very accessible and the dev tools for the radio’s microcontroller were available from the manufacturer. After these discoveries, there really was only one thing to do: write new firmware for a $40 radio, and making a great tool for playing around in the 2 meter and 70 cm bands.

The instructions for reflashing the firmware on this radio only require an Arduino and a handful of miscellaneous components. [Lior]’s new firmware for the uv3r radio isn’t quite finished yet, but he plans on adding some really impressive features. Things like a better UI for a four-button radio, a mode for tracking satellites, a digital mode, and a computer-controlled mode are all possible and on [Lior]’s project wishlist.

Getting a $40 radio to do your bidding with an Arduino is cool enough, but [Lior] says this mod for the uv3r can be taken even further: if you’ve got an amateur radio license, it’s possible to use the uv3r to control an Arduino or other microcontroller from miles away. It’s a great hack, right up there with the USB TV tuner/software defined radio thing we saw almost exactly one year ago.

You can check out a demo of some custom software running on the uv3r after the break. The radio listens for a DTMF tone (supplied by the uv3r’s big brother, the uv5r), and plays back a three-digit DTMF tone. There’s also a more through walk through of what [Lior]’s new radio can do as well.



12 thoughts on “Writing New Firmware For A Handheld Radio

  1. The other day a ham radio friend asked me if I thought more people were getting into the hobby, to which I replied, “Yeah, but it’s probably just the crazy prepper crowd.”

    But I see I was wrong. Ham radio has always been about geeky experimentation, and hacks like this have me convinced that tradition still has a bright future ahead. Kudos!

    1. Since everybody has cellphones a lot of the thrill of portable communication people used to have is a bit gone though.
      But there are situations where radio is still the thing to go for though.

      1. I understand the UV-3R comes in 2 or more versions, with different hardware, like a move from single line display to 2 lines and such, so I wonder if they changed the microcontroller too.

        And does that 5R also have different versions? Mark 1 and 2 and such.

        As for those lines, I see those are described in some controllers as::

        MICO Microphone amplifier output. Put a feedback resistor to adjust gain
        MICI Microphone amplifier input
        RXO Receiver amplifier output. Put a feedback resistor to adjust gain
        RXI Receiver amplifier input

        So I guess that might apply here.

  2. I love how thanks to this dude’s curiosity we gained $40 programmable 2 band radio.
    Next step is for Codec2 to mature enough for someone to port it into hardware (maybe stm32 72mhz is enough?) and cram into one of those radios so we can have digital walkie talkies :)

  3. I’ve been meaning to comment; Lior’s done some good work on this, and has gotten me to think about adding some features to a more powerful CPU that can be substituted for the one that comes in the UV-5R. Perhaps one of these days I’ll go into more details on that elsewhere.

  4. I’ll take a better CPU, Codec2 AND D-Star in one radio; I’m trying to figure out how to do this and still fit it inside the stock case. It may end up being a little bit thicker, but I just may manage it.

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