Latest update from Jonathan....
Status - 3 March 2016.
Things are moving on nicely. A number of repeaters have opened up with the MMDVM, usually as DMR only, and I think many more are on their way. I would imagine that the number of MMDVM systems could top the 100 mark within a few months.
For the most part development is now slowing down, due to the various elements reaching maturity. So here is the status of each major component:
D-Star. This is pretty well complete and some serious bugs squashed within the last few weeks. The host D-Star repeater is simpler than the D-Star Repeater, but that’s fine by me as the original repeater software has become rather large to say the least. It’s possible/probable that some of the extra functionality of it will migrate over to the host, but I’ll be careful about which parts.
DMR: This has been the most fun to implement, lots of interesting and varied techniques to learn and use. The DMR side is pretty well complete. The only known missing part is the regeneration of ¾ rate data, so if anyone can give me some pointers as to how to progress I’d appreciate it. I can probably do the encoding, but decoding has me baffled.
Fusion: This is a mess. The more time I spend with it, the less enamoured with it I become. The host is RF only, and I don’t see that changing in the foreseeable future. Fusion has some great ideas, but most of it is pretty poor, and doesn’t lend itself to network transportation, unless you exclude VW mode, which would be a shame. I consider Fusion to be a curiosity! Any help in regenerating the audio would be appreciated. I think I have the callsign part correct, but I’m not sure.
Modem: Apart from supporting the STM32 series of chips, the only enhancement planned is to allow the MMDVM to co-operate with another repeater controller to form a multi-mode repeater (i.e. FM + MMDVM). This will include adding two new pins, one would be an MMDVM “I am busy” pin, and an input from the other controller to say that it is busy and the MMDVM should not operate. In later boards these pins will be added, but in the interim I have a quick and dirty solution. For a DMR only MMDVM, you can use the transmit out line to lock out the other controller, and I will add a compile option to allow the currently unused COS input to be used as the MMDVM lockout input.
Display: I will add support for other displays in due course, it’s a matter of identifying suitable ones that are cheap. The currently selected Hobbytronics display isn’t cheap, I know, but it fits the bill nicely. I am sure others will too.