OpenGD77

Guys

As I have both a GD-77 and Baofeng DM-1801 in pieces at the moment, I've made a youtube video showing the similarities and differences.

I think there is a high probability that I should be able to get the OpenGD77 firmware working on the DM-1801, however the internal connections from the CPU to the key elements of the radio, e.g. the mic, speaker, DMR chip, LEDS, PTT button etc etc are mostly different.
Hence although I can re-encrypt the OpenGD77 binary file so the Baofeng bootloader will accept it, only the display and part of the keypad appear to work at the moment.

Well, it also looks like the AT1846S chip is partially functional, but thats about it.

However, I think its just a question of spending a few hours using a continuity tester to work out the connections to the MicroController, and then the firmware should work.
And, I'll also need to work out the keypad mapping as it has 2 extra buttons!


youtu.be/EyWjvL0vz-E

great informative video, the 4 way key design looks a bit fiddly and, as you mentioned, the pressure on the screen would worry me.

i think i would rather buy another gd77 than the baofeng.

please don't abandon the gd77 in favour of the newer baofeng.

I'm definitely not abandoning the GD-77

The Baofeng radios seem to have worse RF performance than the GD-77.
I have seen some spectrum analysis plots of the RF Tx from a Baofeng RD-5R and it was quite dirty.

But since I already have one of these radios, I thought I may as well take it apart and potentially get the OpenGD77 firmware to run on it.

BTW.

I said in the video that there was an antenna switch chip, but I now don't think these radios have an antenna switch chip.

i have a DM-5R here (their first bodged attempt), they should just stick to analogue.

The early Baofeng UV-5R analog FM radios were quite dirty, throwing significant spurs and modulation byproducts. They were so bad that US FCC regulations for type acceptance were being violated for Part 90 (commercial FM private mobile radio standards). The radios were banned from importation into the USA.

After that, new versions of the radios were refined to pass the standards. They were still dirty, but not so dirty as to fail evaluation testing. With Part 90 acceptance, the new versions were imported again to the USA.

Their first digital versions of these radios DM-5R were initially shipped with Tier 1 operation only supported. Eventually, refined versions supported Tier I and Tier II operation.

https://ve3ips.wordpress.com/2016/09/16 ... er-beware/

The analog BF-5R was eventually type accepted in later versions:
https://fccid.io/ZP5BF-5R

Their Radioddity RD-5R is similar to other models:
https://fccid.io/2AJGM-DM-5R/Letter/Dec ... ty-3772971

Their revised radio was marketed as the Radioddity RD-5R, and is Tier II timeslot 1 and 2 compatible.

https://fccid.io/2AJGM-DM-5R

Here's the Part 90 acceptance for the 2018 version of the DM-5R. You can see the radiation spurs here.

https://fccid.io/2AJGM-DM-5R/Test-Repor ... rt-3772982

The company making all these operates under a large number of brands and corporate identities:

https://fccid.io/2AJGM

Here's the FCC evaluation page for the DM-1801:

https://fccid.io/2AJGM-DM1801

from http://members.optuszoo.com.au/jason.re ... 77mods.htm
i saw GD77 USE W25Q80BV 1M spi flash,and DM-1801 use 25Q16 2M,so need to change SPI driver to work on it.

bg7iyn wrote: ↑

Mon Mar 02, 2020 2:29 am

from http://members.optuszoo.com.au/jason.re ... 77mods.htm
i saw GD77 USE W25Q80BV 1M spi flash,and DM-1801 use 25Q16 2M,so need to change SPI driver to work on it.

I don't think this makes any difference.

I have some special GD-77 from the TYT factory with 8M flash chips and they work OK.

Its probably just the connections which are different, as it just uses GPIO pins as all the SPI are used for the connection to the C6000

VK3KYY wrote: ↑

Sun Feb 23, 2020 11:04 am

I'm definitely not abandoning the GD-77

The Baofeng radios seem to have worse RF performance than the GD-77.
I have seen some spectrum analysis plots of the RF Tx from a Baofeng RD-5R and it was quite dirty.

But since I already have one of these radios, I thought I may as well take it apart and potentially get the OpenGD77 firmware to run on it.

BTW.

I said in the video that there was an antenna switch chip, but I now don't think these radios have an antenna switch chip.

Yes,GD-77 have Better RF TX performance,so,don't abandon.

Definitely not abandoning the GD-77. Its the primary platform.

DM-1801