Spark 2 + BrewBlox OneWire Temp sensor


Im trying to get a OneWire temp sensor working on my Spark2 with the latest version of BrewBlox. I have now 4 One Wire sensors, 2 are unknown, 1 is brand new and the 4th is known working with a Spark 3 & BrewPi. Im unable to get any to register with the Spark2 when clicking ‘Discover New One Wire Blocks’.

As you can imagine, having no working temp sensors makes using the Spark2 with my brew setup a little challenging!

Am I missing something? How can I troubleshoot this?

Try them one by one. A defect sensor can take down the bus. It is almost certainly a hardware issue.

Did you get the sensors from us?

Hey @Elco ,

I got the Spark second hand so unsure where the temp sensors came from. It came with 2 - one looks identical to the ones on the brewpi store (epoxy set, rj11), the other has heat shrink around the top of the probe so prob not from you. I got the latest one last week from an online NZ store.

If the bus goes down, does the spark need restarting to recover or does it auto recover after a period of time?

It should find the sensors again, but you might need to click to discover them again.

The shrink wrap kind is shit, one water gets underneath the shrink wrap, it shorts or rusts the contacts and the sensor will fail.

The new one, did you attach an RJ11 probe yourself and did you check that it had the correct pinout?

Im certain one of the sensors came from the BrewPi Store as I have borrowed it from a friend who has a Spark 3 with 3 temp sensors - assumption is all bought from store. The 3 sensors work with his Spark 3 & BrewPi software.

This new sensor won’t be in liquid, so less concerned about shrink wrap.

The new sensor is attached to an RJ11 by me, it follows the same colour coding and pin out as the pre-purchased RJ11 and labelled pin out on bottom of Spark.

New sensor or re-made (known working) rj11 sensor are detected in any RJ12 port.

I lost the plot a bit. Do some sensors work with the spark 2 or none?
If none of the sensors work, it could be that the onewire bus master ic on the board was damaged or that one of the rj12 connectors is creating a short (spring pins pushed against eachother).

Hey Elco,

No, no sensors work on the Spark 2.

Have visually checked rj12 connectors, all look good. So I guess its an IC issue. I’ve flashed the spark back to BrewPi firmware and setup a BrewPi server, it also didn’t find any temperature sensors.

Is the bus master IC something that I can replace, im competent with electronics to a good level.


It is this IC that is most likely the problem:

If you have the skills and equipment to replace an 8 pin SOIC component, it is worth a try.

On a Spark 2, is it using the 6 pin DS2482?

Sorry, it’s the 6-pin DS2484R on the Spark 2.