хаха, китайсы такие китайсы: http://www.edaboard.com/thread352836.html
I've just checked and the problem was really caused by fake chinese DS18B20 chips. I've also created simple test to tell if your device is fake.
1.) Connect to your bus master
Fake does not work in parasitic mode while original does In fact fake will put down whole bus.
2.) Test using multimeter (i guess most reliable)
Diode test: + lead on DQ, - lead on DCC. Original DS18B20 will show nothing, fake will show approx 1.4V drop.
3.) Test powered devices using computer to find them in your network
default errata/trim value of fake devices is always 65535 while on real thing it can vary
default templow/temphigh values of fake device is -1/-1, while 70/75 on original?
I've written more info here:
https://wiki.spoje …/navody/electro/1-wire