Hello everybody, I've read almost all the posts about this topic on this forum and of course elsewhere on the net. I have an old RPi B+ and I'm trying to connect 4 DS18b20 temp sensors. These are wired on 3 to 5 m length ethernet cat 5 cable in star topology.
When I check
everything is fine, I see all 4 sensors detected and getting right temp. When I try to read temperature periodically after some time sensors start to give wrong CRC check and unreal temperature(-62C) and at some point I lose them (they dissapear from the folder). If I shorten the interval between readings, sensors tend to go into bad state and dissapear earlier. If I leave them connected without any readings, they stay connected for a long time.
I have 4k7 resistor and I don't use parasite power (I use 3.3V pin for power). From what I have read, one wire protocol is somehow sensitive in timing. Could this be an issue, when the RPi gets bigger load (more readings use more resources)? I don't thing this is an issue with wiring, since everything stays connected if there are no readings, is it? I would love to hear any suggestions, thanks