Build your own homebrew MMDVM hotspot


After the online resources to mount its full duplex MMDVM digital repeater based on Arduino and Nucleo STM32F4, here is the time to explain how to set up a “homemade” access point (Hotspot) MMDVM  based on a few simple elements:

  • A “STM32Duino” board based on STM32F103 CPU, which we will program with MMDVM (firmware)
  • A RF transmitter/receiver UHF RF7021SE (ADF7021) circuit board providing a few RF milliwatts
  • a simple PCB circuit that allows the interconnection of the STM32F103 and RF part
  • and always the Raspberry Pi (to host MMDVMHost).
  • For firmware loading purposes, a TTL serial USB adapter

The purpose of this article is to guide you step by step through the process of assembling the physical parts and then to explain you the software configuration. We will complete the installation with a user-friendly Wifi connection management software (RaspAp).

Synoptic view of MMDVM HotSpot

If you would be interested to participate in a possible future new grouped order (MMDVM board, SvxLink Card), leave your email below to be reported!

9 thoughts on “Build your own homebrew MMDVM hotspot

  1. Bonjour,
    très beau tuto Christian, merci !


    Very nice tutorial Christian, thanks !


  2. Hello, I have been reading your very informative website, as I am in the process of setting up my Hotspot.
    The question I have is what UHF frequency do you set your MMDVM to?

    Is it a special simplex frequency which is also programmed into your P25 ,DMR, Fusion, D-Star radios?

    Or is it a UHF frequency of a local reflector to your QTH.

    Sydney Australia

    Bonjour, J’ai lu votre site très instructif, car je suis en train de mettre en place mon Hotspot.
    La question que j’ai est : quelle fréquence UHF définissez-vous votre MMDVM?

    Est-ce une fréquence simplex spéciale qui est également programmée dans vos radios P25, DMR, Fusion, D-Star?

    Ou est-ce une fréquence UHF d’un réflecteur local à votre QTH.

    Sydney, Australie

    1. Hello Colin,

      The frequency of the hotspot is to be programmed in your stations in simplex (RX = TX).
      For example 435000

      Bonjour Colin,

      La fréquence du hotspot est à programmer dans vos postes en simplex (RX=TX)
      Par exemple 435000

  3. where is the PCB info file for gerbers and or also where can the PCB be made
    où est le fichier d’information PCB pour les gerbers et ou aussi où le PCB peut-il être fait?

  4. What is the current usage of the adf and stm and it be connected to the pi by a usb connection

    Quelle est la consommation actuelle de l’adf et du stm et lorsqu’il est connecté au pi par une connexion usb?

    1. Trent,

      I just measure, the electrical power consumption of this hotspot using a Raspberry Pi 3 is 0,36A under 5,25V. When disconnecting the hotspot (remains alone the pi), then the current is down to 0,34A.



      Je viens de mesurer, la consommation électrique de ce hotspot fonctionnant avec un Raspberry Pi 3 est de 0,36A sous 5,25V. Lors de la déconnexion du hotspot (seul le pi reste) le courant est réduit à 0,34A.

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