OneWire wiring / daisychain

1

OK this is probably a dumb question- but I’m not sure how to wire up the OneWire expansion boards. I’ll be controlling a heater, cooler, fans and a light. I’d like to take advantage of the OneWire plug to have only one wire coming out of the brewpi.

Questions:

Do I just use standard RJ-11 to connect from BrewPi->Expansion Board? I did read that the RJ-11 pinouts need to be to the same pins, not crossed. And I guess RJ11 is actually just 2 conductors. Should it have 4, or 6?

Can I then daisy-chain the expansion boards? By just using another cable from board->board (which leaves a plug open for a temp probe which is cool).

Sorry for dumb questions- thanks for the help.

Eric

2

You will need a 4 wire RJ11 to the Expansionboard. It should NOT be crossed. You are also able to use RJ12 with 6 wires but the 2 outmost will not be used in this situation.

The pinout is as follow (from left):

RJ12 (6pin)

RS485-A, 12V, 5V, GND, OneWire, RS-485-B

RJ11 (4pin)

12V, 5V, GND, OneWire

You are able to daisy chain the boards as they are on a Onewire bus. And yes you are able to connect tempprobes in the left over ports. The temp probes is using 5V, GND & Onewire only.

3

OneWire bus :wink: But on the PCB, the Photon does talk to the OneWire bus master via I2C. I2C is not very suitable to talk over longer distances, that is why the outer pins of the board have RS485 as alternative to OneWire.