Is there an affordable 1-Wire Humidity Sensor that can be used with BrewPi?


I’m looking for my Fridge a Humidity Sensor that can be used with the BrewPi Spark.
This is not for Beer Fermentation itself but I’m thinking of using this setup for Dry Ageing meat where I need to control and check the humidity as well. The BrewPi Spark would work perfectly for that, just need a humidity sensor that I can connect.

Thanks in advance.

As far as I know there are no 1-wire humidity sensors.
The best way to do this I think is to use a second microcontroller to interface the humidity sensor and let it talk to the BrewPi Spark over RS-485 (via serial to RS-485 chip MAX3082).

There’s also the DS2450 A-D converter. (I don’t recall if these are discontinued.)

It’s also possible to emulate the DS2450 using a tiny AVR -

Something like a DHT22 or DHT44 might work for Thomas’s application. I would imagine the BrewPi could be modified to utilize them fairly easily as they work perfectly with Arduinos. They’re technically three wires though, similar to the DS18b20’s - GND, vcc & Data, but unlike the DS18b20’s, they’re not addressable, so you can only have one on each data pin.

Derp (edit)… after thinking about it I realized you meant 1-wire as in the same technology as the DS18b20’s, not ‘one wire’.

here is a 4 port ad 1wire adapter that may be hacked, at on 16 bucks it may be worth it. are you going to do charcuterie ?
I have wanted to get in to salami making for some time.

alternative to the DS2459
Dallas DS2450 emulation with Tiny AVR

this may also be of some use to both of you.
this guys appear to be running a humidity sensor off of a 1 wire battery monitoring chip , it has a temp sensor and analog inputs <— 1wire temp with AD inputs <---- humidity sensor

Emulating a OneWire slave in a microcontroller is not allowed by Maxim. You can make software OneWire masters, but not slaves. So while I could make them, I would not be allowed to sell them, which is why I added RS-485.

The battery monitor IC would be a good option.

Maybe another good option would be to make a versatile I/O board with a microcontroller and RS-485 chip. It could interface various analog sensors, have fast PWM outputs and more.
The same board could be reprogrammed to read analog sensors, drive pumps, read thermocouples, etc.

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I think the simplest way to do this would be to use an Arduino (Uno or Nano) to bridge between a DHT22 and the RS485 bus on the BrewPi Spark. There are plenty of examples of using DHT11/22 sensors out there. I would think that the Spark would need additional programming to be able to interpret signals sent from the Arduino to log the humidity/temp data sent by the DHT22. The DHT22 does indeed have a 1-wire protocol, but this is not compatible with the Dalls One-Wire protocol that we all know and love. As an alternative, you could run my CellarWarden temp/humidity logging program on the RPi that hosts the BrewPi Spark’s web server (shameless plug!). This will provide an easy way to monitor temp/humidity using a DHT11 or DHT22 and also provides SMS/email alarm functionality.

Hmm. Would that mean that my fridge, where the humidity sensor will be, need additionally the arduino to get the humidity data?

There must be a simpler way to just connect a humidity sensor to a Photon or Spark via the brew pi and read the data every other second or so. That all sounds far to complicated.

What the brew pi does very well is connecting the temp sensors and SSR in very simple way. And now with etxtension boards even better.

Why are humidity sensors not as simple as the temp sensors? Any technical reasons?

PS: I want to use my fermentation fridge as well to make dry aged rib eye steaks from a full rib. With the Temp sensors, Temp control and fan I can do that. Only part that is missing is the humidity. Should be dry but not to dry.


Humidity sensors are quite simple, but the BrewPi Spark was not designed to interact with them. Maybe Elco will add this functionality at some point, but I know he’s quite busy working on ferm control and brewing control. There are no humidity sensors that are available that use the Dallas One-Wire protocol, so interfacing with the BrewPi Spark would need to occur over the RS485 bus, and the BrewPi would need to be programmed to handle this. As I mentioned, the simplest way to log humidity would be to use your RPi that serves up the BrewPi web server and connect up a DHT11 or DHT22 and use logging software like CellarWarden ( CellarWarden was inspired by BrewPi and is designed to do exactly what you want. That seems pretty easy, no?