MMDVM Modems for MTR2000 & MASTR III

MTR2000 Version

KS-DMR and WA0EDA are not affiliated with Repeater Builder and do not support Repeater Builder products.

Purchasing a Modem

Modems are built when there is a demand for 10 or more. The STM32-DVM-MTR2K and STM32-DVM-MASTR3 are not recommended for those without prior knowledge of MMDVM/MMDVMHost, the MTR2000/MASTR III, and a basic ability to use the UNIX/Linux CLI. WA0EDA does not provide direct support for MMDVMHost, radio programming software, or end-user radio code plugs.

Contact Cort Buffington, N0MJS at for more information

Manuals, Articles & Tutorials


Much of the circuitry of the STM32-DVM-MTR2K and SMT32-DVM-MASTR3 is the same. Both use the same filters, the same modem processors, NanoPI NEO single board computer, etc. Most of the information contained here is applicable to both.


Articles & Tutorials:

Binary Application File Updates

Binary Application Files for All Modems. Copy in place over old versions, update the appropriate .ini files for new features and restart.

Compiled on September 1, 2021. Latest versions of the applications as of this date. Minimal .INI files changes from previous versions include the following, but I do not use all features, other items may have changed as well:

[DMR Network] Type=(Direct|Gateway)
[Log] FileRotate=(0|1)                         #ALL .INI FILES
      DisplayLevel=(log level)                 #P25 Gateway
      FileLevel =(log level)                   #P25 Gateway
      Static=(comma separated gateway IDs)     #P25 Gateway, replaces "Startup"
      RFHangTime=(seconds)                     #P25 Gateway, reworked activity timer
      NetHangTime=(seconds)                    #P25 Gateway, reworked activity timer

NanoPi NEO Almost every modem ever sold

OrangePi Zeroonly used for VERY early modems

Firmware Updates

Binary Modem Firmware Files For Both Boards.
(Instructions for updating are in the manual).

Compiled on September 1, 2021. Latest version of MMDVM as of this date. Includes support for all modes. Please ensure you are using the proper version for the STM32 variation on your modem. Compatible with PiStar v4 and newer.

  • STM32F446RET6 – STM32-DVM-MTR2K V1.0, V2.0a, V2b, (some) V2.0c

Schematics and PCB Layouts



Older Firmware Updates

Compiled on July 27, 2020. Includes support for DMR, D-Star, YSF, P25, NXDN, POCSAG, FM. This version expects the function of the COS input (COS or Inhibit) to be set in the MMDVM.ini file for MMDVMHost. It is NOT compatible with PiStar builds prior to version 4 for the NanoPi NEO as of August 2020.

Compiled on December 5, 2019. Includes support for DMR, D-Star, YSF, P25, NXDN, POCSAG. These versions ARE compatible with the PiStar builds for the NanoPi NEO as of August 2020.

Binary Firmware Files for the STM32-DVM-MTR2K I/O Processor
(Instructions for updating are in the manual)

  • ATMEGA328P – 20200404 release with startup light show


The artwork is licensed under the Creative Commons BY-NC-SA 4.0 share-alike license. Which means you may do anything non-commercially you like with it, but you must provide attribution, even if you modify it. Which means you can pretty much do whatever you like, but you have to give credit to the Regents of the K0USY Group, and we prefer you just use the EDA logo.

Older Versions and File Archives