OpenGD77: flashing GD-77, DM-1801, RT3S and MD-UV380 — step by step, with a backup

OpenGD77 is a free (open-source) firmware for DMR radios built on the NXP MK22 + AT1846S + HR-C6000 chips. It literally brings cheap "bricks" to life: a convenient interface, a built-in DMR ID database (you see the callsign and name of whoever is talking), flexible zones and scanning, a VFO mode, no commercial restrictions and active community development. Below is how to install it cleanly and how to roll back to the factory firmware if you ever want to.

Which radios are supported

Step 1. Install OpenGD77 CPS

Download the OpenGD77 CPS programmer from the official site opengd77.com and install it (at the end the installer will offer drivers — accept them). You will use this same CPS both to flash the firmware and to edit the codeplug.

Step 2. Make a backup so you have a way back

You can return to the factory firmware — but only if you have a backup. Right after installing OpenGD77 (or before it, if the CPS can read the stock firmware), use the CPS menu to save to disk: Flash, EEPROM and MCU ROM. Without these dumps you will not be able to restore the original.

Step 3. Put the radio into flashing mode (bootloader)

The key combination depends on the model. With the radio off, hold the buttons and apply power:

• GD-77 / GD-77S / DM-1801 / RD-5R: hold SK1 + SK2 and switch on. A green LED will light up and the screen stays dark — that is normal.
• RT3S: hold PTT + SK1 (the small button above PTT) and switch on. The LED will start blinking green and red.
• MD-UV380/390, DM-1701, MD-9600: hold PTT + the button above PTT and switch on — the radio will enter DFU mode (the STM DFUSe driver is required).

Step 4. Flash the firmware

1. Connect the radio to the PC with a cable (use the bundled cable for GD-77/DM-1801, a regular USB cable for STM models).
2. In OpenGD77 CPS open Extras → Firmware loader.
3. Select the exact model of your radio.
4. Point to the .bin firmware file (get the latest version from opengd77.com). Flashing starts right after you pick the file — it takes less than a minute.
5. When it finishes, turn the radio off and on as usual. The OpenGD77 screen should appear.

Step 5. Load a codeplug and the ID database

Fresh firmware means an empty radio. Next you need to load a codeplug (channels, zones, contacts) and the DMR ID database. If this is your first time building a codeplug, we have a separate walkthrough — the logic is the same for any CPS.

Returning to the factory firmware

Put the radio into the same bootloader, in the Firmware loader select the official firmware (or restore your saved Flash/EEPROM/MCU ROM dumps via the CPS). This is exactly why we made the backup in step 2.