DS18B20 temperature sensor sends 85 °C error value

[Robert.Wall]

@borpin

I think it is a single 10M to the breakout board and star from there (which should be fine - keep all the ‘star’ points the same length).

Not according to the literature: Guidelines for Reliable Long Line 1-Wire Networks | Analog Devices. Star points are only good with short distances to the sensors. Bus “daisy-chain” is the recommended method, with (as I wrote) a minimum length spur off the bus to the intermediate sensors.

It’s all been discussed before:

DS18B20 reliability considerations

Saw the stuff on DS18B20 sensors. I have had quite a few fail for various reasons and know quite a bit about the failure modes. First ones were hand soldered by me to CAT5 cable with heat shrink over each pin and then heat shrink over the assembly. They started failing in less than a few months after being buried. Was worse when it was wet. The ones that were not directly buried failed after a couple of years. Solid core CAT5 is not a good idea for this application. Next I purchased t…

Ds18b20 and emonTX3CM firmware - post 78 in particular.

I fully expect our antipodean colleague to weigh in before long.