tristantech
commented
8 years ago I became curious about this too. I think it has something to do with the vocoder. The IC is called the HR_V3000S according to the schematic. There is very little information out there about it, sadly. I found lots of other Chinese DMR radios mentioning use of the "DVIS HRV3000" as the vocoder. I presume "DVIS" is a knock-off of DVSI, which makes the real AMBE vocoders. "HR" is the same prefix as the DMR processor IC. It would not surprise me that China has reverse engineered or implemented the AMBE+ spec. I don't think this 6-pin chip is actually the vocoder, but perhaps it's a hardware token/dongle to activate the actual vocoder inside the STM32? I see that the pin map refers to it as a watch dog peripheral, but that doesn't seem to fit in.
Tapping the I2C bus would provide some valuable information. There is also a pack of code called "HR_V3000-vocoder-use" floating around on a bunch of sketchy Chinese download sites that you can find through Google. They make you either pay or upload lots of stuff to get the files. I think it would be very interesting to get a look at whatever that code is.
aeickho
kb9mwr
next week, i'll look on the calling functions .. to see with task is involved and i'll look to find the I2C address
on https://github.com/travisgoodspeed/md380tools/issues/40 --> Software Control Watch Dog Serial Clock Software Control Watch Dog Serial Data