Confirming original onewire connections

Can anyone help me confirm my onewire connections. I’m covering to a spark unit and installing RJ12 connectors for the temp sensors.

RJ12 Pins:
1 - Blank
2 - Blank
3 - Green - power
4 - Black - ground
5 - Red - data
6 - Blank

Is this correct?

Note that my older onewire Colors are:
Green - Power
Red - Data
Black - Gnd

I think the new onewire wires are:
Red - Power
White - Data
Black - Gnd


You’re correct on all counts. For reference, the RJ12 pin layout can also be found on the sticker on the back of the Spark.

Hey, thanks for the quick reply. I can’t seem to get the Spark to recognize any of my three Onewire sensors. I have a newer one (that now comes with the RJ11 connector) and this one is recognized. The old ones were working fine with the Arduino. At this point I’m guessing I’ve damaged the old ones somehow. Think I had them connected wrong, initially as I mistakenly thought the red wire was +5V not data. Maybe I toasted them electrically?

If your Spark is connected to Brewblox, you can check the spark service logs (docker-compose logs --follow spark-one). An event is logged when a new OneWire device is connected.

If your physical wiring still allows you to connect your wires to Pi pins, you could try to implement a quick pi-side script to verify your sensor / wires.

I’d consider it unlikely that connecting data to 5V would fry your sensor, but there’s no way I can confirm or deny that remotely. A bad connection in your wire or your RJ12 connector also is a very real possibility.

I’ve looked at the logs and I don’t see anything that indicates an error with respect to the old temp sensors. It did say it successfully connected with the new onewire sensor.

I pulled the RJ12 connectors off and connected them to a manufactered telephone cable, just in case I made an error in using the modular plugs. This allowed me to verify the continuity with my multimeter. So I’m confident that they are wired and connected properly.

Next step is to try your recommendation going direct to the Pi. I’m more of a hardware guy (EE) and less of a software guy so this is my path of least resort. A quick look at the link you shared tells me I’ll need time to implement.

Thanks again,

1 Like

If you connected the data line to 5V it is likely that you have damaged the sensors.
If they are not recognized by the spark when data and ground are correctly connected, consider them toasted.
I would not waste time testing them another way.

Thanks. That was my first thought.

Btw, congrats on the installation process for Brewblox. So much easier than the first time I built my BrewPi, way back in 2015.


Temp sensors are good!
Last chance/question, I’m using RJ12, 6 pin modular plugs. Would I be better off using the 4 pin RJ11 plus?


RJ11 is fine. They are exactly the same, except that RJ11 only has the 4 pins in the middle. Form is the same.

The outer pins are used for RS485, so irrelevant here.
What did you change to make it work?

I reinstalled the Arduino. That was really the easiest as I used a new SD card for the Spark build. Just had to remove the RJ12 Jacks and reconnect the old terminals. .

I’ll order some RJ11 Jacks and try again. Or, I might just order new sensors that you have with the Jack’s installed along with the new expansion board.

By the way, does the old one wire expansion board work for this application? I suspect it would, but I do like the new version that supports the two SSR’s as well!


After multiple tries with my existing sensors and various connectors, I Brooke down and just bought new sensors from the store and…
Everything works. So much for my technician skills! Elco/Bob, thanks for the help. I’ve now repurposed my Arduino and old Pi3 and working from the Spark setup.