In this guide we are going to explain how an Anytone AT-D868UV walkie talkie can be converted into the new model AT-D878UV, since there are only software differences between both, the hardware being the same.
Although to do Honor to the truth, this last statement is not strictly true. There are three different versions of the Anytone AT-D868UV in terms of hardware:
- V1 : It carries a microcontroller model GD32F303V E of 512 KB of Flash. It uses the firmware V1 (v1.xx).
- V2 “initial”: It has several design changes and improvements on the PCB, but still uses the GD32F303V E of 512 KB of Flash and V1 firmware (v1.xx). Yes, somewhat confused.
- “Final” V2: It’s like the “initial” V2, but it has a model GD32F303V G with 1 MB of Flash and uses firmware V2 (v2) .xx)
In Spain this walkie arrived a year late and apparently all the units correspond to the “final” version V2, so potentially all are convertible to the AT-D878UV, with which it shares hardware.  How to know if your unit has the GD32F303V E or the GD32F303V G ? Very easy, open it. It is the most reliable way. At the time of writing this article has not yet found a correspondence between hardware versions and serial numbers, so the only way is to open it. Later I explain how. Remember that the convertible version carries the GD32F303V G .
What features and functionalities will we gain with the conversion?
- APRS by FM (“analog”)
- APRS configurable via menu from the walkie
- Roaming (automatic change between DMR repeaters)
- Support for Talker Alias
- New high contrast color scheme
- And future improvements of the AT-D878UV, since the development of the AT- D868UV seems to be paralyzed from the market launch of the new model
This is an experimental procedure that completely nullifies the warranty and can damage the device irreversibly.
Personally I have been able to convert several units of satisfactory form, and none has suffered any type of damage. However, I can not guarantee that these steps will work for your unit, nor will I be held responsible for any damages you may cause. If you go ahead, it is under your full responsibility.
For operation it has been used the following materials:
- ST-Link V2 (AliExpress)
- Set precision tweezers in different ways ( Amazon )
- Torx T9 ( Amazon )
- Breadboard 3 male-male cables ( AliExpress )
Windows need a system where we have downloaded all of the following:
- ST-LINK Utility
- Anytone AT-D878UV Firmware (mostrecent available)
- Anytone AT-D878UV Bootloader
- Anytone AT-D878UV Testmodes
1. Previous steps
1.1. Export our current codeplug from the CPS that corresponds to the firmware version we have on our AT-D868UV.
1.2. Record the Serial Number and the date of manufacture of the equipment that appears in the “Local Information” section, since it is corrupted during the process and it must be restored at the end.
Beware, that the serial number that appears in this window it is different from the one that appears on the back sticker of the equipment, under the battery.
1.3. Make an MCU Reset. To do this, you have to turn it on by keeping PTT + PF1.
2.1. Remove the antenna and battery.
2.2. Remove the two Torx screws that are housed in the lower part of the walkie, under the battery.
2.3. Remove the two upper wheels (volume and channels). They leave simply by pulling firmly.
2.4 Unscrew the metal part of the antenna connector. To do this, we can help with a flat-tipped screwdriver or clamp.
2.5 . Remove the rubber that lodges in the hollow of the antenna with the help of a pair of tweezers.
2.3. Unscrew the metal parts of the upper wheels. Again with the help of a flat-nose pliers or screwdriver
2.4. Separate the metal chassis from the plastic housing with the help of a flat object. Leverage a little bit carefully in one of the corners.
2.5. Disconnect the flex ribbons. There are two tapes, one thick for the screen, and one thinner for the GPS. We must push the mechanism with the help of curved tweezers to release the tapes. This operation must be done with care, since both the connectors and the tapes are very delicate.
2.6. Separate the plate from the front. Eye, that in this step will fall two black rubber bands lodged in the hollow of the wheels of channels and volume. We must not lose them.
2.7. Check the MCU model we have. If it is the GD32F303V G then we are in luck. The chip is the one that appears in the lower right corner, the largest on the board.
3. Preparation of the ST-Link
3.1. Connect the ST-Link to the breadboard cables. The three pins of the ST-Link that we need are:
- SWCLK (clock signal)
- SWDIO (data)
- GND (mass)
Be careful, because there are ST-Link models that have the pins in different order. Look at the serigraphy of yours.
3.2. Build a connector that fits into the holes in the board. In my case I used a bit of bodybuilder tape to keep the pins together, and I have doubled the pins so that they have the correct distance between them.
The direction of the terminals according to the walkie in the images is:  Clock – Ground – Data
4. Replacing the bootloader
This is where we perform the transformation of the AT-D868UV in AT-D878UV. We are going to change the bootloader by writing directly to the MCU’s flash memory, which will cause the CPS to recognize the unit as a genuine AT-D878UV and allow us to load its firmware.
4.1. Insert the battery. I have fastened it with a plastic wire. You can also use flanges, rubber bands, or even nothing if we are careful. The battery supports quite well on its own.
Battery clamped with a plastic wire 4.2. Configure the STM32 ST-Link Utility. For this we must go to “Settings”, set the connection type in 4.0 MHz SWD mode, and “Normal” connection mode.
4.3. Full backup of the MCU flash. In order to reverse the conversion, or recover the walkie in case something has gone wrong, we will make a full backup of the chip. To do this, we will configure the following memory address and dump size:
- Address: 0x08000000
- Size: 0x100000
Once established the parameters we will do the following:
- “Target / Connect”
- “File / Save”, and preferably put “.hex” extension
This file is very important because it will allow us to go back in case we want to revert conversion or problems arise, so we should keep it in a safe place and remember.
4.4. Replacing the bootloader. This is where the conversion happens. We will need this file:
Next, let’s write it on the walkie. For this, we will perform the following steps:
- With the walkie off, we will turn it on in firmware update mode by pressing and holding PTT + PF3 (orange button). The LED will flash red
- We connect the ST-Link cable to the walkie board
- We go to “Target / Program & Verify” in the menu
- We select the downloaded file “878MCU_bootloader.hex” before
- Mark “Verify while programming”
- Then press “Start”
- The programming of the bootloader is completed in less than 1 second.
5 . Loading the firmware of the AT-D878UV
5.1. Loading the firmware. We will download the last CPS corresponding to the model AT-D878UV and upload its firmware following the instructions of the manufacturer as with any other update to use. In essence it would be:
- Turn on in firmware update mode by pressing and holding PTT + PF3 (orange button). The LED will flash red.
- Use the CPS to write the firmware on the walkie.
- Turn on the factory reset mode by pressing and holding PTT + PF1. It will ask us if we want to reinitialize the walkie. We say yes.
5.2. Update of icons. Again, following the manufacturer’s instructions, we will load the icon update into the walkie.
- Turn on icon update mode by pressing and holding PTT + PF2
- Use the CPS to write the icon update on the walkie.
6. Restore the number of series
6.1. Download and unzip the following ZIP: Anytone AT-D878UV Testmodes
6.2. Open the file “normaltestmode.CDD” with a hexadecimal editor. For example, for Windows we can use HxD .
6.3. Find the position in the file where the serial number is located and write ours on top. It is very important not to delete anything of what there is, since in that case we will displace the contents of the file. We must click on the first digit and then write the digits of our serial number, overwriting existing ones.
6.4. We can do the same with the date of manufacture if we have previously annotated it.
6.5. Icon update mode. We must turn on icon updating mode by pressing and holding PTT + PF2.
6.6. Write the file on the walkie. We go to the CPS, choose “Tool / Firmware Upgrade” in the menu, and write the file “normaltestmode.spi” in the walkie as if it were a firmware update to use.
7. Restore the codeplug
7.1. Restore the codeplug from the CPS.
7.2. Update the DB of contacts. We can take advantage of the moment to upload the most recent database to the walkie.
7.3. Check the configuration of the walkie. The AT-D878UV has new configuration options. Take a look at the CPS to leave it to your liking.
And that’s it. At this point we should have a fully functional walkie-talkie AT-D878UV in which we have available all the new features of this model, and standard updates from CPS.
Now to enjoy it.
This guide is based in a collection of information from different sources, ordered and organized conveniently to provide a clear and simple procedure to follow.
The information has been obtained from: