Progress of opengd77 on DM1702

BI4ILQ
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Progress of opengd77 on DM1702

Post by BI4ILQ » Sun Mar 12, 2023 6:55 pm

BD4VOW mentioned that DM1702 has different pcb designs to support GPS functions. will opengd77 support this model? I wonder if opengd77 will be updated to support the APRS function?

VK3KYY
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Re: Progress of opengd77 on DM1702

Post by VK3KYY » Sun Mar 12, 2023 8:34 pm

GPS support can be added easily if the connection pins to the GPS module are known

FM APRS.

Tx may be possible but not Rx, because there is no direct audio path from the AT1846S FM TRx IC to the CPU

No one had time to try to write code to test whether the hardware, is capable of generating the audio tones needed for 1200 baud.

The radio hardware is not designed for this purpose, so no one knwos if this is possible using the tone generators in the AT1846S or HR-C6000

BI4ILQ
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Re: Progress of opengd77 on DM1702

Post by BI4ILQ » Mon Mar 13, 2023 3:36 am

OK, Maybe the APRS function is not necessary. I want to know whether 1702 is on the future support list of opengd77? Because it supports GPS and is cheaper.I can also help with the work of localization.

VK3KYY
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Re: Progress of opengd77 on DM1702

Post by VK3KYY » Mon Mar 13, 2023 7:15 am

I don't have any information about the hardware in this radio

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Re: Progress of opengd77 on DM1702

Post by VK3KYY » Mon Mar 13, 2023 8:49 am

KenFromNN wrote:
Mon Mar 13, 2023 8:41 am
Looks like there is teardown video on Youtube: https://www.youtube.com/watch?v=SGcaRGApYKE
It is named "Baofeng DMX DMR Radio Quick Raw Teardown" i.e. about Baofeng DMX, but it seems that hardware is the same.
It is not possible to write firmware based on a video teardown

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BD4VOW
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Re: Progress of opengd77 on DM1702

Post by BD4VOW » Mon Mar 13, 2023 10:32 am

VK3KYY wrote:
Mon Mar 13, 2023 8:49 am
KenFromNN wrote:
Mon Mar 13, 2023 8:41 am
Looks like there is teardown video on Youtube: https://www.youtube.com/watch?v=SGcaRGApYKE
It is named "Baofeng DMX DMR Radio Quick Raw Teardown" i.e. about Baofeng DMX, but it seems that hardware is the same.
It is not possible to write firmware based on a video teardown
I've ordered one with GPS today, If I have time, I will try to do some research on this model.

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BD4VOW
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Re: Progress of opengd77 on DM1702

Post by BD4VOW » Mon Mar 13, 2023 6:22 pm

The porting of any new model is not something that can be promised.
This is a non-commercial open source project. The team members are using their spare time to participate in the project.
If you are interested in porting a new model, you can reverse engineer the related model , and feedback the technical details obtained to the team, so that it is possible to make effective progress.

SP2ONG
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Re: Progress of opengd77 on DM1702

Post by SP2ONG » Thu Mar 16, 2023 9:43 am

Hi,

I own one DM-X radio (DM1702) and if I can make an OpenGD77 version for this model I will be happy to test it.
I realize that it's a long way to go to make OpenGD77 for this radio and it requires a lot of work and may not succeed
but I keep my fingers crossed and wish Amo good luck

73 Waldek

VK3KYY
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Re: Progress of opengd77 on DM1702

Post by VK3KYY » Thu Mar 16, 2023 10:26 am

Additionally, It is not just the hardware which has to be reverse engineered

The firmware encryption also needs to be cracked

I did a quick search and found this

https://github.com/OK2MOP/MD1702-tools

But I can't see any encryption key data

I also checked RadioTool https://github.com/v0l/radio_tool

but it does not support the DM-1702 / DMX

If you are serious about porting to this radio, I'd recommend you first find all possible versions of the manufacturers official firmware and start to analyse those firmware files.

They will be encrypted, but often the header can be identified because it may be the same for all firmware versions.

The TYT radios like MDUV380 and MD9600 and the DM-1701 effectively use the same key for all firmware versions, but the GD-77 doesn't exactly do this

The GD-77 has an additional value obfuscated in the header, which is different in each firmware version, and is a seed into the encryption table. This made it much more difficult to Kai DG4KLU to originally crack the GD77 firmware encryption

You'll also need to understand how the firmware is loaded into the radio. i.e in bootloader mode is it a STM DFUSe device like the STM32F405 based radios, or is it a custom bootloader protocol.

It seems that most STM32 based radios use a modified STM DFU bootloader with encryption / decryption added, but this does not seem to be the case for MK22 based radios

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BD4VOW
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Re: Progress of opengd77 on DM1702

Post by BD4VOW » Fri Mar 17, 2023 3:43 pm

Reverse engineering ongoing...
Image

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