
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 n0mjs@me.com 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.
Manuals:
- STM32-DVM-MASTR3 Version 1.0a
- STM32-DVM-MTR2K Version 2.0c
- STM32-DVM MTR2K Version 2.0 I/O API Addendum
Articles & Tutorials:
- Compiling MMDVM Firmware for WA0EDA Modems
- STM32-DVM-MTR2K and an External Analog Controller
- STM32-DVM-MASTR3 and an External Analog Controller
- Build Your Own STM32-DVM-MTR2K
- STM32-DVM-MTR2K: V2 Host I/O Communication Firmware Update
- STM32-DVM-MTR2K: The Story Behind it, and the Future
- Coming Soon: STM32-DVM-MTR2K V2.0
- Configuring MMDVM for the MTR2000 and STM32-DVM-MTR2K
- STM32-DVM-MTR2K: Deep Dive – Updating Firmware
- MTR2000 and STM32-DVM-MTR2K: Analog + Digital, Playing Nice Together
- Programming an MTR2000 for the STM32-DVM-MTR2K
- Introducing the STM32-DVM-MTR2K
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 [Network] 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 Zero – only 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.
- STM32F405RGT6 – STM32-DVM-MTR2K V2.0c, STM32-DVM-MASTR3 (MOST MODEMS)
- STM32F446RET6 – STM32-DVM-MTR2K V1.0, V2.0a, V2b, (some) V2.0c
Schematics and PCB Layouts
STM32-DVM-MASTR3 V1.0a
STM32-DVM-MTR2K V2.0
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.
- STM32F446RET6 – STM32-DVM-MTR2K V1.0, V2.0a, V2b, (some) V2.0c
- STM32F405RGT6 – STM32-DVM-MTR2K V2.0c, STM32-DVM-MASTR3
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.
- STM32F446RET6 – STM32-DVM-MTR2K V1.0, V2.0a, V2b, (some) V2.0c
- STM32F405RGT6 – STM32-DVM-MTR2K V2.0c, STM32-DVM-MASTR3
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
STM32-DVM-MTR2K/MASTR3 CAD/CAM Files
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.
- MTR2K
- Gerber and Excellon Drill Files
- SMD Assembly Files for JLCPCB/LCSC (maybe others)
- STL file (zipped) for Ethernet extension mounting bracket
- STL file (zipped) for Nextion 3.2″ display (clips to the front grill, no holes required).
- MASTR3
- Eagle Schematic/PCB Files
- Gerber and Excellon Drill Files
- SMD Assembly Files for JLCPCB/LCSC (maybe others)
- STL file (zipped) for card front
- STL file (zipped) for card front handle
- STL file (zipped) for card rails (best printed with PETG or ABS – not PLA)
Older Versions and File Archives
- Schematic diagram V2.0a/b
- Printed circuit board diagram V2.0a/b
- STM32-DVM-MTR2K Manual – V1c and V2a)
- STM32-DVM-MTR2K V1c schematic diagram
- STM32-DVM-MTR2K V1c printed circuit board diagram
- STM-32-DVM-MTR2K V1c-a Schematic diagram
- STM-32-DVM-MTR2K V1c-a Schematic diagram (update)
- STM32-DVM-MTR2K V1c-a Printed circuit board diagram
- ATMEGA328P – 20200105 release with host I/O communication
- ATMEGA328P – First release version I/O Processor used in v2