OpenGD77 User Guide

OpenGD77 User GuideOpenGD77 manual

OpenGD77 User Guide updated

I’ve now updated the OpenGD77 User Guide to include the new features in the Tier 2 Alpha 2 release.

A PDF of the guide can be downloaded from here

Notable changes to the functionality in the Tier 2 Alpha 2 version are as follow.


OpenGD77 Phase 1 User Guide

This user guide is a work in progress as is the Open GD77 firmware. If you find any errors or omissions please let me know so they can be corrected.

Due to the rapid pace of development some of photos of screens are now out of date, because the DMR TS and CC are now down shown on all DMR screens.

The photos will be updated when the firmware is not changing so quickly

The intention of the OpenGD77 firmware is to create a new fully featured non-commercial firmware that entirely replaces the Radioddity GD-77’s factory firmware. This firmware is specifically designed for Amateur Radio use, and has features not available in the official firmware.


The firmware is still under development and there are some key areas of functionality which have yet to be written.

1.    Currently the stable firmware only works on DMR with simplex hotspots or to other DMR radios for simplex contacts. This is because the firmware currently does not fully support DMR Tier 2 required for most commercial and MMDVM repeater systems.

However DMR mode can be used with a simplex hotspot and for DMR simplex operation.

There is pre-release (Alpha) version which supports Tier2 , repeater and duplex hotspot operation, but it currently has some minor issues.

Note. The Tier 2 version does not currently support Hotspot mode

2.    FM Rx and Tx transmission works.

This includes repeater operation using CTCSS on both Tx and Rx.

3.    On DMR, only Talk Group “calls” and Private calls are currently possible

Text messaging and other similar features are currently not supported, but are on the To Do list.

For a full list of current bugs, and proposed enhancements see

Now onto what’s great about the OpenGD77 firmware…

The firmware is designed for Amateur Radio use, especially on DMR, and has a number of features for Amateur Radio use which are not normally available on commercial DMR radios.

These include direct numerical entry of DMR TalkGroup numbers and use of the Rx Group list to control the TG’s selectable for each DMR “channel”

Also, as far as possible the firmware is open source. This allows anyone to modify the firmware to suit their own individual needs, and also for peer review and improvement of the firmware source code


Conceived by Kai DG4KLU, including development of the framework and all the FM and DMR Tx and Rx (Tier 1) functionality.

User Interface, Display driver, Codeplug API, EEPROM memory API, Flash memory API, Hotspot mode and many other features developed by Roger VK3KYY

Tier 2 repeater operation developed by Roger VK3KYY

Additions from Colin G4EML, including FM CTCSS and “All Channels” zone functionality This user guide: Alister G0NEF and Roger VK3KYY

Thanks to all the Beta Testers that provide detailed bug reports and user feedback, especially VK7ZCR, W1RHS and G4TSN

Download OpenGD77 Phase 1 User Guide

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