Radioddity GD-77 - Open Community Firmware


About two years ago, I first took the plunge into DMR radio with the GD-77, at the time it was one of the relatively few sub-$100 DMR radios that supported both UHF and VHF on the same platform. For those who are unfamiliar with DMR, there is a remarkably sharp learning curve. The programming software (CPS) that comes with most radios does nothing to ease the transition, the GD-77 also has a few particular quirks which interrupt normal reception, often requiring the radio to be put into “promiscuous mode” in order to receive programmed talk groups. If this sounds like a negative review of the GD-77, it very much is, there are some desirable features vs other DMR radios on the market, and it’s very acceptable as a difficult-to-program analog radio.

The GD-77 was a complete disappointment as a DMR radio. One of the additional problems that complicates the management of the GD-77 is the firmware/CPS software versions are highly dependent on being of a similar build and generation, without agreement between these two bits of software, a codeplug might be written to the radio, however, attempts to test would be met with esoteric messages like “Be TX Fail”. In most cases, performing a factory reset was the only way to back out of this.

Enter the OpenGD77 Project. Previously there was what was called a “community edition GD-77 CPS” (now depreciated) which worked well. However, the new OpenGD77 provides substantially more than just a less buggy programming interface, that is compatible with the existing CPS (offering the same plus a few expanded options). Most importantly, the project also includes OpenGD77 firmware which makes radical improvements to the user interface as well as the display.

There are a few downsides to the OpenGD77 firmware, the principle complaint is the firmware has it’s own static setting for the control buttons. Meaning, you can’t simply set the accessory buttons to your desired features. Here is the firmware button mapping:

The other downside to the OpenGD77 Firmware is you lose the capability of accessing the encryption features of DMR. Not that these features are particularly strong, and yes, there are very valid points to turning this feature off as far as international compatibility (a lot of countries have put key escrow regimes into place fairly recently) as well as here in the US encrypted communications over amateur radio is limited to a single case by the FCC: Satellite control.

With all of that said, the OpenGD77 Firmware is worth checking out if you happened to buy a GD77 and haven’t been very happy with it’s performance. It really breathes new life into the radio and fixes a lot of long-standing issues I’ve had. The instruction manual provides a very good tutorial for how to install the new Firmware, and rather than duplicating any of that effort here, I suggest referring to the manual, as I’m positive some of this process may change with time.

  • Open GD77 User Guide
  • Author