New project: External Ruuvi sensor boards

Current monitor, with accumulator or averaging. Something like the INA226, or so. Or a Maxim state-of-charge IC.

Is there a way to set up a poll on this forum or elsewhere?

Is a PIR a

Passive infrared sensor


Yes, it detects presence in area.

How a about an FSR? That would host for a range of new uses to RuuviTag:-)

Do you mean a force sensing resistor, e.g. a strain gauge?
Adding one on a same board with other sensors would probably expose the other sensors to too high mechanical stress, but we can consider it once the first board is out.

Yes, a force sensing resistor - but not actually ON the board. More like a connection that could be easily used for connecting an FSR (or several depending on physical space available) + software support on RuutiTag side to easily utilise it. Currently no board offers integration of FSRs with an easy way to transfer the data in BLE broadcast mode.

@lauri In regards to the temp range exceeding 85C, the DS18b20 is a very inexpensive 1-wire temp sensor with a range of -55C to 125C.

Any 1-wire sensors (temp, humidity, etc) are welcome.

I am using PLCs that support 1-wire sensors. I can run a few wires through a facility (or misuse a LAN cable), and then drop sensors anywhere I want… they simply show up on the “1-wire network”.

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Actually, we’re already prototyping with TMP117. It’s a lot more accurate sensor and can measure temperatures from –55°C to +150°C.

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what about an Thermocouple interface?

It certainly would be useful for something like oven thermometers. It might even be enough to activate both pull-up and pull-down resistor on ADC and take differential measurement off the thermocouple, with no extra components required.

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I like the ideas. Can we get a 3.5 mm jack for using it with an IR Blaster cable / Current Transformer for ac current measurements ? If not then how about an IR Blaster with ~4 IR transmitters and 1 IR receiver?

What about cases for all these sensors? Both the IR and VOC would need a special case to not block the signal and to allow enough air flow.


The sensor board will be wired externally outside the case, naturally this will mean that the external sensor board won’t have the IP67 rating of Ruuvi enclosure.

Idea is to make the sensor boards easy enough for anyone to make their own, maybe we should make one variant which has the connectors and 0.1" through holes for easy prototyping (@lauri)

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interesting idea. I’d like to try to measure a higher temperature (around 200 ° C) using a two-wire platinum sensor PT100 / 1000. the required accuracy is not great 5-10° C. do you think it really works?


PT100/1000 -sensors are resistive and quite expensive. It’s easier to measure thermocouple voltage directly with ADC and I’d think that temperature range and accuracy you’re looking for could be reached

Hi lauri!
Very helpful would be
a CO2 - sensor (for example SCD30 or its successor, or K30 (high precision, but ext. power required), or CozIR LP2
a O2 Sensor (like Alphasense LFO2-A4 or Membrapor M100) via LMP91000 or NJU9101 /I2C)
Would make the Ruuvi to a perfect HVAC control unit and more…

Voltage and Current for my caravan battery

But voltage also opens a range of analog sensors

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1-wire temp sensors and 1-wire addressable switches for sure. The switches can turn on actuators for closed loop control!

Is Ruuviconnector available for Ruuvitags?

On the next circuit board revision, yes. We’re currently testing the board and it’s projected to be mass produced starting from the H2 2021.

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