2025-10-14 Project Update
Published on October 14, 2025 by Michael Rickey AF6FB
Goals we are currently working on
- I/Q Radio
- As the ADF7021 gets closer to end of life we have been working with ZUM Radio to evaluate a new option.
- In our goals for our current grant we mentioned the SX1255, AT1846, and the WL33 chips as possibilities.
- ZUMRadio created boards for the AT1846 and WL33 for evaluation at no cost to MMDVM.
- ZUMRadio’s evaluation of the AT1846 showed the chip is not stable enough for our uses. This was abandoned.
- The WL33 was evaluated by ZUMRadio and by an outside developer (Martin Alcock) that has experience with the WL33. MMDVM paid Martin for this work. We have decided STMicro has not built support for what we need to do.
- For the SX1255, ZUM Radio has created test boards for software development - work on the driver code is being done at no cost to MMDVM. We are planning to show this board sending different modulations at Pacificon 2025.
- TNC Mode
- This work is complete and the source code is in the MMDVM GitHub (https://github.com/g4klx/MMDVM-TNC) repository. It is being used by people now and is the subject of a talk at the Zero Retries Conference (https://www.zeroretries.org/p/conference) in September.
- MMDVM will support this as needed and resolve issues as reported.
- Transcoder and Cross-Mode operation
- This topic contains two of the original goals. Using a prototype board, developed and donated by ZUM Radio, we have this working now.
- When a production candidate becomes available we will do final integration work as needed.
- The final product may be implemented with a single AMBE3003 or two ABME3000 chips. The current software supports either option. The final decision is up to ZUM Radio.
- Source code is available in the MMDVM GitHub repository (https://github.com/g4klx/MMDVM-Transcoder)
- PCB design and Gerber/BOM files are available at https://github.com/ZUM-Radio/MMDVM_transcoder_hw
- This is a feature users can manually configure now, while we wait for it to be implemented in WPSD and Pi-Star.
- Integrate MQTT work into release packages WPSD and Pi-Star
- The MQTT work is complete.
- It will not be put in end-user hands until implemented by WPSD and Pi-Star.
- Users can build the MQTT branch and configure MQTT now, they just won’t be able to use images from WPSD and Pi-Star.
- Add support for new modes
- Initially we talked about implementing dPMR and TETRA.
- dPRM is unique to Europe and TETRA requires the I/Q board.
- This is where we would like to ask for a change to our goals and work on a new Digital Voice mode called GT-DV.
- Convert MMDVM to Platform.io and deprecate firmware reliance on ST-Micro’s Standard Peripheral Libraries (SPL) and move to newer HAL/LL
- Newly created code, like the transcoder, has been developed using Platform.io.
- MMDVM-TNC is already based on platform.io
- Additional modules are being converted as we work on them.
- We are about 30% complete on this.
- ZUM Radio has donated development of the new platform.io drivers needed to build code for all the STM32 chips likely to be used going forward.
- Deprecate the MMDVM_HS firmware and move to only use MMDVM firmware
- We have decided to leave the ADF7021 based firmware (MMDVM_HS) as is and combine the new RF chip (likely the SX1255) into the MMDVM firmware.
- We feel this is a better choice than moving ADF7021 support into the MMDVM firmware.