Pink silkscreen

MicroModem Prototype


Out of stock


One MicroModem, hand-assembled, fully tested and flashed with the firmware of your choice. By default, I will ship it with MicroAPRS KISS firmware. If you want something else, let me know in the order comments!

This is a prototype board that does not match the build-quality of the final product, be sure you understand the differences before buying! This prototype is functionally identical to the finished MicroModem, and there is nothing wrong with them, but they have a few shortcomings that I adressed in the final hardware design. It’s very cheap though. Might be great if you just want an extra modem to mock around with :) You should read this post for more info on this board!

The differences are: The silk-screen text is a bit miscolored, so it is not really white, but has a pink hue. The connectors are not as good quality as the final MicroModem. The PTT transistor is a through-hole version instead of surface mount, making the board a tiny bit taller. The board may have a green receive LED instead of the blue one of the final product.


  • ATmega328p @ 16MHz (4KB RAM / 32KB flash)
  • Powered from USB or external regulated 5V source
  • 51mA idle power consumption
  • Operating range: -20°C to 70°C (non-condensing)
  • Modulated analog output level adjustable from approximately 15mV to 1.5V peak-to-peak
  • Minimum analog input level for good decode is about 100mV peak-to-peak
  • ADC running on 3.3v reference
  • Arduino compatible (You can program the board from the Arduino IDE, over USB)
  • Connectors:
    • USB Mini-B (USB-powered)
    • Audio out (modulator output)
    • Audio in (demodulator input)
    • Ground x2
    • VCC (5V) x2
    • 3.3V output (Max current 50mA)
    • PTT_V+ (for Kenwood style PTT)
    • PTT (logic level PTT signal)
    • UART – RX / TX (Arduino pins D0 & D1)
    • I2C – SCL / SDA (Arduino pins A4 & A5)
    • SPI
      • SCLK (Arduino pin D11)
      • MISO (Arduino pin D12)
      • MOSI (Arduino pin D13)
      • DTR (Reset pin)
  • Flexible firmware support, use one of the provided firmwares, or create your own!
    • APRS SimpleSerial
    • MP1
  • Arduino APRS library available, create your own APRS firmwares easily!
  • All firmwares are Open Source, and available on GitHub
  • Hardware design is Open Source, and available on GitHub


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