2 ms·

Nice CO2 graph. What did you use for the sensor & logging system? I bought an off-the-shelf CO2 monitor to tell me when I should open a window, but I can't extr

by sxp 6y ago

Nice CO2 graph. What did you use for the sensor & logging system? I bought an off-the-shelf CO2 monitor to tell me when I should open a window, but I can't extract the sensor readings from it. Any recommendations on good sensors compatible with standard home measurement systems? I have a Sense Hat for my RPi that logs temp & humidity and would like to add CO2 to it if possible.

sbierwagen 6y ago
It's a SCD30 talking to a flask.py script that logs the data with sqlite. Graph is done with plotly.js. All hacked together quickly, none of it working terribly well. Never tried to hook it into a home automation system. The SCD30 carrier board I used was one of the Seeedstudio grove units: https://www.digikey.com/products/en?mpart=101020634&v=1597 https://www.digikey.com/products/en?mpart=101020634&v=1597 Seeed says it's a 3.3/5V compatible unit, so you could even use it with your Pi if you buy a Grove base hat to add to your stack. I'm using it at 5V, so I don't have any direct experience with that configuration, though. In my experience the SCD30 autocalibration is worthless, so put it outside and manually set it to a plausible number. I used https://www.pmel.noaa.gov/co2/story/Space+Needle https://www.pmel.noaa.gov/co2/story/Space+Needle as a reference. I think the Grove library ran it at a 2 second poll rate by default, which results in a substantial amount of sensor self-heating. (It draws 75mA while reading co2, since it's a spectrometer) This gives you a tradeoff between accuracy and data staleness, I just run mine at 20s and point a fan at it. If you build it into an air handling unit, which is its intended application, that's not a problem.
- chx 6y ago
  > It's a SCD30 talking to a flask.py script that logs the data with sqlite. Graph is done with plotly. https://html9responsiveboilerstrapjs.com/ https://html9responsiveboilerstrapjs.com/ > 2. How do I install this? Um... are you stupid or something? Just attackclone the grit repo pushmerge, then rubygem the lymphnode js shawarma module – and presto! Here I am with twenty years of a programmer career, more than 15 years of that with open source (just to illustrate I am not unfamiliar with hacking) and ... uh ... I open the balcony door from time to time and air the bedroom before going to sleep. I am too old for y'all.
  - sbierwagen 6y ago
    I mean, I hadn't used flask since 2014, and had never used sqlite, plotly or an esp8266 (as a wifi transceiver) before. The project was intended as a learning exercise for playing around with those tools. Someone who just wants a CO2 sensor would buy https://www.amazon.com/dp/B0784TZFRW/ https://www.amazon.com/dp/B0784TZFRW/ , which isn't much more expensive than my pile of components and has way more functionality; and someone who was interested in the messing with technology aspect would want to figure it out for themselves. There's maybe 200 lines of code total, in the entire project. Someone who wasn't as determined to wander into blind alleys as I was could do it in a weekend.

by sxp 6y ago

sbierwagen 6y ago

It's a SCD30 talking to a flask.py script that logs the data with sqlite. Graph is done with plotly.js. All hacked together quickly, none of it working terribly well. Never tried to hook it into a home automation system. The SCD30 carrier board I used was one of the Seeedstudio grove units: https://www.digikey.com/products/en?mpart=101020634&v=1597 https://www.digikey.com/products/en?mpart=101020634&v=1597 Seeed says it's a 3.3/5V compatible unit, so you could even use it with your Pi if you buy a Grove base hat to add to your stack. I'm using it at 5V, so I don't have any direct experience with that configuration, though. In my experience the SCD30 autocalibration is worthless, so put it outside and manually set it to a plausible number. I used https://www.pmel.noaa.gov/co2/story/Space+Needle https://www.pmel.noaa.gov/co2/story/Space+Needle as a reference. I think the Grove library ran it at a 2 second poll rate by default, which results in a substantial amount of sensor self-heating. (It draws 75mA while reading co2, since it's a spectrometer) This gives you a tradeoff between accuracy and data staleness, I just run mine at 20s and point a fan at it. If you build it into an air handling unit, which is its intended application, that's not a problem.

chx 6y ago
> It's a SCD30 talking to a flask.py script that logs the data with sqlite. Graph is done with plotly. https://html9responsiveboilerstrapjs.com/ https://html9responsiveboilerstrapjs.com/ > 2. How do I install this? Um... are you stupid or something? Just attackclone the grit repo pushmerge, then rubygem the lymphnode js shawarma module – and presto! Here I am with twenty years of a programmer career, more than 15 years of that with open source (just to illustrate I am not unfamiliar with hacking) and ... uh ... I open the balcony door from time to time and air the bedroom before going to sleep. I am too old for y'all.
- sbierwagen 6y ago
  I mean, I hadn't used flask since 2014, and had never used sqlite, plotly or an esp8266 (as a wifi transceiver) before. The project was intended as a learning exercise for playing around with those tools. Someone who just wants a CO2 sensor would buy https://www.amazon.com/dp/B0784TZFRW/ https://www.amazon.com/dp/B0784TZFRW/ , which isn't much more expensive than my pile of components and has way more functionality; and someone who was interested in the messing with technology aspect would want to figure it out for themselves. There's maybe 200 lines of code total, in the entire project. Someone who wasn't as determined to wander into blind alleys as I was could do it in a weekend.