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IO Environmental Monitor: Notes and Suggestions
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IO Environmental Monitor: Notes and Suggestions

by AtomicPenguin on Tue Apr 27, 2021 8:08 pm

First of all, thanks to Brent Rupell for his educational "Adafruit IO Environmental Monitor for Feather or Raspberry Pi" Lesson. Very nice, and I learned a truckload.

I have a couple of suggestions/comments:

1. The advent of sensors with STEMMA connectors obviate the need for all the soldering. This makes the project much easier for "solder-challenged" folks. (I used a SparkFun Qwiic pHAT v2.0 on top of an RPi Zero W.) So you might wish to update the lesson - mentioning the option of using STEMMA connectors.

2. The "Small Plastic Project Enclosure - Weatherproof with Clear Top" makes a great project case. However, as the author is probably aware, the clear polycarbonate cover attenuates almost all of the UV radiation. (You may wish to mention this fact in the lesson.) So the UV sensor will be reading unrealistically low. Accordingly, I made a small hole in the cover, and mounted an Adafruit LTR390 UV sensor (which has STEMMA connectors) so that the sensor "looks" through the hole. Of course, the hole blows the "weatherproof" aspect, but you can't have everything.

Gary
Chief High Roboticist,
Will Robinson Memorial Robot Research Center

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Re: IO Environmental Monitor: Notes and Suggestions

by brubell on Fri Apr 30, 2021 10:46 am

Brent here- thank you for the feedback!

1. The advent of sensors with STEMMA connectors obviate the need for all the soldering. This makes the project much easier for "solder-challenged" folks. (I used a SparkFun Qwiic pHAT v2.0 on top of an RPi Zero W.) So you might wish to update the lesson - mentioning the option of using STEMMA connectors.


Yep, I'm considering updating this project to solder-free but there's no ETA.

2. The "Small Plastic Project Enclosure - Weatherproof with Clear Top" makes a great project case. However, as the author is probably aware, the clear polycarbonate cover attenuates almost all of the UV radiation. (You may wish to mention this fact in the lesson.) So the UV sensor will be reading unrealistically low. Accordingly, I made a small hole in the cover, and mounted an Adafruit LTR390 UV sensor (which has STEMMA connectors) so that the sensor "looks" through the hole. Of course, the hole blows the "weatherproof" aspect, but you can't have everything.


" the clear polycarbonate cover attenuates almost all of the UV radiation" Could you elaborate?

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Re: IO Environmental Monitor: Notes and Suggestions

by AtomicPenguin on Mon May 10, 2021 10:53 pm

Brent -

Sorry for the delay in replying.

In direct sunlight, with an LTR390 sensor, I got a UV reading of 132 without the poly cover, and a UV reading of 1 when the poly cover was in place.
In indirect sunlight through a glass window, I got a UV reading of 16 with no cover, and a UV reading of 5 when the cover was in place.

If you look at the datasheet for the LTR390, it shows a UV response curve that peaks at a wavelength of around 320 nm. Then search the web for "polycarbonate UV shielding" and I think you will find that the poly will shield almost everything below about 400 nm.

Anyway, thanks again for a very interesting and educational project.

Gary

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Re: IO Environmental Monitor: Notes and Suggestions

by brubell on Fri May 14, 2021 9:34 am

interesting - thanks for the info!

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