3 ms·

I needed to test the impact of a product we were developing on the air temperature distribution of a room (it really is warmer at the ceiling) so over the cours

I needed to test the impact of a product we were developing on the air temperature distribution of a room (it really is warmer at the ceiling) so over the course of a weekend I strung up 27 OneWire temperature sensors in 9 strings of 3 from the ceiling of my living room and wrote a script running on an mBed microcontroller (like an Arduino) that would poll the OneWire bus every 30 seconds and send the responses back to my laptop which would then record the data in a CSV for me to graph once the test was done. This also required me to make a OneWire library from the OneWire spec as back then there was no public implementation for running on an mBed. This test data formed the backbone of that company for the better part of a decade as it clearly showed when our product was running the temperature at the ceiling (across the whole room) reduced by 2degC and at the mid point of the room (head when sat in a sofa height) it rose by 2degC. Our product acted as a destratifier and the test rig to prove it took me from Friday evening to Sunday night to make as I was working elsewhere at the time.

anfractuosity 3y ago
That's a cool idea, I guess it was maybe ds18b20 you used? I'm curious if a very low resolution thermal imager such as Grideye could act in a similar fashion if you scanned the room using servos (https://www.adafruit.com/product/3538 https://www.adafruit.com/product/3538 is an example of a breakout board). Not sure of the accuracy though of such sensors for measuring temperature. Edit: Just noticed they have "an accuracy of +- 2.5°C" so not good enough I guess, whereas ds18b20 claims 0.5C.
- simonbarker87 3y ago
  > ds18b20 Yes that's the one. I couldn't remember/be bothered to check Thermal camera would only work if there was a surface to get the temperature of, we needed to know the temperature of the air in the middle of the room rather than the walls etc. We did think about hanging ping pong balls on string like the sensors I hung but then yes, accuracy becomes an issue compared to the ds18b20. Also this was in 2011 so I don't think we had the same variety of embedded device compatible stuff available and a proper thermal camera was out of our budget. Fun side note, I brought the test rig back to life a few months ago for fun, found the OneWire lib code I wrote, copied into the Arduino project (mBed was long gone) and it worked with about 2 minutes of tweaking. That's 13 year old code up and running like no time had passed ... I can't even imagine the pain of bringing back a 13 year old web project!

anfractuosity 3y ago

That's a cool idea, I guess it was maybe ds18b20 you used? I'm curious if a very low resolution thermal imager such as Grideye could act in a similar fashion if you scanned the room using servos (https://www.adafruit.com/product/3538 https://www.adafruit.com/product/3538 is an example of a breakout board). Not sure of the accuracy though of such sensors for measuring temperature. Edit: Just noticed they have "an accuracy of +- 2.5°C" so not good enough I guess, whereas ds18b20 claims 0.5C.

simonbarker87 3y ago
> ds18b20 Yes that's the one. I couldn't remember/be bothered to check Thermal camera would only work if there was a surface to get the temperature of, we needed to know the temperature of the air in the middle of the room rather than the walls etc. We did think about hanging ping pong balls on string like the sensors I hung but then yes, accuracy becomes an issue compared to the ds18b20. Also this was in 2011 so I don't think we had the same variety of embedded device compatible stuff available and a proper thermal camera was out of our budget. Fun side note, I brought the test rig back to life a few months ago for fun, found the OneWire lib code I wrote, copied into the Arduino project (mBed was long gone) and it worked with about 2 minutes of tweaking. That's 13 year old code up and running like no time had passed ... I can't even imagine the pain of bringing back a 13 year old web project!