@computar, yes the voltage generators are controlled by 3bits each, this is correct. For 3bits we have 2^3=8 values of voltage for each voltage generated and I think that is enough. The big range of chips are not so big, they artificially inflated the supported list, you will find the same chip under many manufacturers and several package types, but in fact is just the same chip.
@BravoV, thanks for suggestion, perhaps this is what i do in the future, right now i will stay here a while. As i seen, many youtubers who watched Dave review landed here and this is good, not to say that a search on Google by tl866 firmware or tl866 schematic will give us first result this thread. But if the project will advance i will create a new thread as you suggested me, thanks again.
For statistical purposes i monitored the links posted and well, people are interested, over 30 countries so far
and this is not real statistics btw. My goal is if possible, to document the protocol used by this device and to help the open source/Linux community because they have always been less privileged. But this is hard work, the manufacturer should do this, but they are not interested, they only provide Windows support and if you have a major problem, like for ex. a firmware corruption then you must buy another device, they will not give you a new firmware, its a shame. But for $50 we want too much. Ok. i was bad, is Easter in my country and i should be good these days.