I've got 3 x 1-wire temperature sensors attached to my EMONTX V3.4 and each of them from time to time displays the default reading of 25.5 C, they are all wired in Screened Cat 6 in powered mode, with a twisted pair between 0 and VCC (3.3V?) and another pair between 0V & Data. If I add another sensor they all stop working and rebooting doesn't help.
Has anyone added sensors directly onto the Pi2 and had them appear in EMONTX? I'm using VLowWrite 8.5
Alternatively will adding a pullup resistor help at the far end of the run which is about 15 Metres away
Re: Has anyone used additional 1Wire sensors directly on the Pi?
Have you looked at the temperature sensors page, and followed up the links, and looked at the Dallas site? There's a lot of good information there about wiring and reflections etc.
Re: Has anyone used additional 1Wire sensors directly on the Pi?
Thanks Robert, I'll take another look at them - I'm guessing they should actually work in multiples on 3.3V and on a Screened Cat6? I was thinking the capacitance may be an issue
Re: Has anyone used additional 1Wire sensors directly on the Pi?
The Pi can be used for 1-wire temp sensors, the default pin unfortunately clashes with the rfm2pi reset pin but can be changed. There is no existing code available for reading the sensors directly into emonhub or emoncms but I suspect it wouldn't be difficult to knock something up.
On the emonTx v2 there was a small manufacturing defect on the PCB that resulted in the temp sensors being delivered 5v, this didn't present a problem for the emonTx's 3.3v inputs, if not running on batteries you could power your sensor network at 5v to "compensate" for the voltage drop from multiple sensors and a long run, this should also reduce any effect of the increased load on the 3.3v rail to benefit the AVR (and free up an AIO)
Just a theory :-)
Paul