The OpenGD77 firmware project is what prompted me to get a Radioddity GD-77 (rebranded TYT MD-760) DMR radio back when the project was just starting out. And that project blossomed and gave us a lot of capability with a firmware designed for ham radio use and easily working with adhoc talk groups all the way to satellite functionality. The firmware project was later ported to the TYT MD-9600 mobile radio, and due to the same CPU chip it’s now been ported to the TYT MD-UV380/Retevis RT-3S dual band DMR handheld radio. And one of the greatest parts of this firmware in the MD-UV380 is it will now support over 300k contacts, and I was able to load the entire DMR database.
https://opengd77.com/viewtopic.php?f=19&t=2380
Worth noting this is alpha software and very experimental, but it’s been working fine on my radio so far with one caveat explained in the forum post above, the ECO modes have not been implemented from the firmware and it uses a bit more power than the stock firmware. But they are working on implementing battery saving modes, but with the complexity of the effort to get that done on the GD-77 it might take a similar effort. The developers don’t have the chip documentation, so some experimentation is required. Also, the screen layout is a carry over from the MD-9600, so some development there will probably ensue possibly making use of the color display. But its absolutely fabulous to get a ham friendly firmware for my TYT MD-UV380 handheld, and if you have one lying around have a look at the instructions and give the firmware a try as it wasn’t that difficult to install (of course I could just load my GD-77 code plug).
Update 9/20/2022: Eco modes have been added to the firmware and battery usage is much improved, but still early testing.
Update 10/01/2022: I’ve been using the 96 MHz firmware as they work on clock speed, and it’s been mostly stable with maybe one RX signal a day sounding like it’s underwater (like the early days of the GD-77 firmware). Here’s what Roger Clark has said they’ve discovered and keep in mind they don’t have the docs on the hardware and are having to experimentally figure out what works best:
We have discovered multiple problems related to the processor clock frequency, the flash memory latency settings, the Serial Peripheral Interface speed.
All of which affect DMR RX and Tx
Its going to take some time to resolve these problems.
https://opengd77.com/viewtopic.php?f=19&t=2403&start=40
TYT Battery Charger Issues:
Some of the TYT battery chargers are over voltage, 8.57 V vs desired 8.4 V, so some took to modifying them while others used a TP5100 chip to replace the built in board. My TYT MD-UV380 charger was over voltage and I installed a TP5100 chip after successfully doing the resistor correction below. But the cheap Chinese TP5100 uses components that vary a bit, so your performance might vary. Mine quick charges fine, but shuts off a bit early before a complete full charge. This is actually better for battery health so I left it, and my GD-77 charger is stock and not over voltage if I need the top off. The benefit of the TP5100 is you get almost an amp of charge until it tapers off for battery voltage, so a nice fast charger which will come in handy until they add ECO modes to the firmware.
TP5100 solution from OpenGD77 forum:
https://opengd77.com/viewtopic.php?f=8&t=564