Hello, I ordered this sensor since the Open air board says 3.3V
https://www.amazon.com/dp/B0C4H5GVDX?ref=ppx_yo2ov_dt_b_product_details&th=1
but the board layout looks like it fits the 5V better.
Has anyone done this yet?
The 5v one looks to fit the space better.
But also be aware that I’m almost certain it doesn’t use the standard orientation of the header pins as shown in the Amazon photos you linked to, but they use a right angle type header I hadn’t seen until this project.
Similar to this:
https://www.airgradient.com/shop/#!/SGP41-TVOC-NOx-Module/p/504083522/category=154292501
I’ve added a BME680 to an AirGradient Pro, but nothing else. I think you would probably end up removing the SGP40 if your device had one, in order to have a header for your own sensor.
I don’t have a TVOC on it. My indoor unit has one though. It would be cool to also be able to add a lux sensor but I don’t know if that is possible. I don’t think the outdoor unit has that level of expansion.
Yes. I added a barometer and a precise humidity/temperature sensors to my Outdoors sensor, because the Plantower temp/humidity sensors are pure crap.
Pretty much all sensors will work, and you can use a bit of wiring if needed. Luckily, you don’t need to ensure airflow for the barometer.
We currently test the build-in temperature and humidity sensor of the Plantower PMS5003T and it is off out-of-the-box. However with the right correction formulas you can get it very close to ambient.
See for example:
We are still collecting data to get a wide range of temperature and will then publish a more official correction factor.
I tried to build a calibration curve and put my sensor into a temperature-controlled fridge. The sensor went mad around -10C and started reporting temperatures around 6400C (no, I don’t live on the surface of the Sun).
But even ignoring obvious bugs, the temperatures were all over the place and not consistent.
Thanks for opening this topic, it made me realize how easy it will be to do this 
I will order two items from Sparkfun:
I’ll only need to find an open area inside the unit where there’s a hole in the PCB that I can use to mount the breakout board, and no soldering (or right-angle header) required
I’m already running ESPHome on my Open Air unit so adding these sensors will be trivial.
Interesting. I just got one of these.
diymore 2pcs BME280 5V Temperature Humidity Sensor Atmospheric Barometric Pressure Sensor with IIC I2C Breakout https://a.co/d/10gv5re
The ENS160 is heated up to operate. Not sure how clever it is to put the temperature and humidity sensor just next to it…
Your graph looks like HomeAssistant. Were you using ESPHome to build the calibration curve?
I was going to look at the calibrate_linear or calibrate_polynomial once I had some real world numbers to plug in and see how it compared, but I don’t have a trustworthy reference device I would compare against.
Yes, I tried to calibrate it for ESPHome.
I have access to some scientific equipment, including a temperature-controlled fridge that I can set to any temperature from +3C down to -35C. Its thermostat is accurate to within 0.5C, and I verified that with a NIST-traceable thermometer.
The idea was to gather enough datapoints, and then do curve fitting ( https://mycurvefit.com/ is awesome for that ). My attempt has failed. Even discounting the hotter-than-Sun bug, the readings were not consistent. For example, if I cooled the sensor down from 0C to -5C, it went from 4C to -2C. However, when I warmed it up back to 0C, the readings went only to 2C.
Out of my experiments, the absolute best sensor was TMP117 ( Adafruit TMP117 ±0.1°C High Accuracy I2C Temperature Sensor [STEMMA QT / Qwiic] : ID 4821 : $11.50 : Adafruit Industries, Unique & fun DIY electronics and kits ). It was off by less than 0.05C from the calibrated thermometer.
So the issue is more the reliability of the sensor readings than a failure of being able to fit it to a curve?
Correct. Temp/humidity sensors on the Plantower sensor are just not reliable enough by themselves. There’s nothing you can do to calibrate that away.
Oh, and the humidity sensor is also pretty useless. It can be 20% RH off.
The red line is accurate, I calibrated the sensor using saturated salt solutions ( Saturated Salt Solutions - Controlling Air Humidity ).
Can you share your raw data with us? Reference and the values you got from the PMs5003T. Then we can use that data together with the one we currently collect and compare.
The 20% on RH seems to match the research AirGradient is doing as well:
How we use Linear Regression to Drastically Improve Humidity Sensor Accuracy (airgradient.com)
Sure. I’ll export the temp data into Excel next week and I’ll post it here.