Moving forward.... Jim just posted on the MMDVM Yahoo list
I'm pleased to announce a big step forward for the open source MMDVM project. There is now support for the ADF7021 RF chip. A lot of work has been going on in the background. A special shout out needs to go to Andy CA6JAU. Without his countless hours of work this would remain a half finished project still sitting on my workbench.
This means mmdvmhost/mmdvm can now talk directly to the 7021 chip so external radios are not needed. In the initial release of source code, there is support for DStar, DMR (DMO), Fusion and P25. Fusion and P25 have not had any significant amount of testing done.
Now to the good stuff. All the source code is currently hosted on Andy's github.
We will be working on getting it merged into the mainline code.
I also posted in the Files section a document with build and installation instructions.
The hardware used during development is a combination of an ADF7021 board and an STM32F103 board. To make it easier to put the parts together I designed a simple carrier board (see attached picture). Everything is thru-hole so most everyone should be able to solder it. As soon as the Chinese New Year break is over, Bruce will be ordering more blank boards.
The stock ADF7021 board needs two modifications. The first is the oscillator has to be replaced with a low ppm TCXO. The second mod is a jumper needed to connect a pin on the 7021 chip to the NC pin on the ADF7021 board header. More pictures will be coming shortly.
The ADF7021 boards are no longer being manufactured. Through his connections in China Bruce has acquired a small number of them and is currently having the two modifications done. His supplier claims to still have some remaining stock. If there is enough interest from the group I'm sure he can try to get more.
If you are interested in helping to test, PM Bruce. He will be in touch with updates on kit availability. We'd like to give priority to those who are more comfortable with the ins and outs of setting up the build environment and able to do the soldering.
what does it mean... it means you can build a Open source hot spot that does all modes for less than $100USD , Yes you still need a computer
Finally... the first small batch of the ZUM boards Rev. 1.0.1 are back from the CM. They have been tested and will be shipping out to people who have been so patient. The big volume will be early January 2017. If your name is on my list I will be in contact shortly. Thanks you for remaining with us !
The port of the MMDVM code to the STM32F4 series has taken a major leap forward As per Jim's email to the MMDVM Yahoo group late last night Does that guy ever sleep :-)
All the source code is already waiting on github. Andy posted the modified Standard Peripheral Drivers in the Files section of the MMDVM Yahoo group. I just posted a text document detailing how to build the code and program the boards.
To start we have support for the STM32F407 Discovery board and the STM32F446 Nucleo board.
I'm attaching a picture of Andy's setup. He's got it working well on DMR. You can also see that he's included the TCXO board for a more accurate clock. I've been doing my testing on DStar.
The instructions include details for building under Windows, OSX and Linux using gcc. There is also limited support for building the code under CooCox (Win32).
After a few long months of designing, testing and fine
tuning, we finally have some concrete things to share with you guys. It might
not be exactly the kind of news you were expecting, but we’re confident you
won’t be disappointed...
Despite our best efforts, the MMDVM revision 1.2 is still
far from completion.
The design we originally envisioned for 1.2 incorporates a
really good filter, but it is quite “aggressive” and requires more work, a lot
more than we anticipated, both in software and hardware.
You probably noticed the messages some of our rev 1.2
testers exchanged on the Yahoo group over the last few months … We tested and
tweaked, and then tested some more but unfortunately it’s just not ready.
A big “Thank you!” goes to all those who helped us design
and test this board. We owe you a beer! (or five?!)
We’ll continue to work on the MMDVM revision 1.2 boards, and
we hope we’ll find a solution
In the meantime, as a small and well deserved reward for
your patience, we’d like to present you a new board: the Rev 1.0.1 board.
We designed the new Rev 1.0.1 board with the following
I2C output (to
A serial output (to
sense and control lines to be used for DR1X conversation
on all the radio signals
The PCBs are ready and they’re heading to the CM. However,
it is mid-November and the timing is not really great. As the holiday season
approaches fast, the deadlines become really fluid… We’d love to tell you that
we’ll ship them in 2-3 week but we simply don’t know.
Our best guess is: “December”…
Once we get into production we will off course be releasing
the schematics (PDF)
A very interesting update from Jonathan posted on the facebook page 8/25/2016
After some investigating by some very clever people, it appears that a simplex (DMO mode) DMR system is possible without having to use radios with very fast TX/RX changeover times. Therefore I have started work on such a mode for the MMDVM. This would potentially allow for a tri-mode simplex gateway since D-Star and C4FM already allow for simplex use.
This will use exactly the same hardware as a duplex MMDVM, the same interface boards for example, but with only one FM transceiver instead of two, and of course no need for a duplexer.
I hope to get the first versions available next week. See the MMDVM Yahoo! group for more details.
Sorry about keeping you in the dark. You know how it is: the family and a full-time jobs leaves us very little time for hobbies. Not to mention the irresistible nice weather (at least up here in Canada)…
That being said, we’re a little bit behind the schedule with the new boards but we’re moving in the right direction.
First of all, the unreleased revision 1.1 that we mentioned at the Dayton Hamvention this year got so many improvements that we decided to launch it as revision 1.2. The change in name won’t affect the end users, but it helps us keep track of the things we do.
Here’s what kept us busy all this time:
• PCB change from 2 layers to 4 layers (New internal layers for 3.3V and GND)
• New filters and amps (designed by EB4FBZ)
• Improved routing of traces
• Added protection diodes to all external pins
• Adding one more op-amp in both transmit and receive paths for new filters
• Added one more radio status and one more control line
• Added two more status LEDs
• Added circuitry for both TCXO and crystal for low ppm clock (the boards will ship with TCXO)
• Corrected long standing connector spacing problem
• Changed from 270 degree turn trimmers to multi-turn trimmers
• Changed critical paths to higher quality resistors and capacitors
• Added solderable jumpers to bypass large bypass capacitors
• Added external RSSI input connector - goes to ADC pin on Due
Thank you for your patience and continuous support!