sensors – MakerBlock

This is the second time the XIAO board stopped working for an extended period of time. Rebooting the board, unplugging/plugging the power cable and adapter from the wall, and even pulling the board from the headers, didn’t work to get it back online. I finally pulled the board, plugged it into USB, then made a do-nothing change to the main.py file¹ and plugged it back into the headers, which worked perfectly. There were no obvious errors in the board – it just … needed a boring update to the code?

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Anyhow, I’d discussed some of the pros and cons of running three Wemos D1 Mini powered sensors² versus just one XIAO ESP32C3 powered sensors – but didn’t think about what happens when a single one goes down. Although the XIAO was out of commission, the three Wemos board kept going so I didn’t really lose any temperature data – especially since the data was so flat during from 12:30 AM to 9 AM this morning.

Admittedly, the locations for the three sensors aren’t perfectly matched. I have the three XIAO thermistors taped to the entryway flooring, taped to the metal plate just inside the family room, and one dangling in the air above the entryway out of any direct sunlight. The three Wemos AHT10’s are on the entryway floor near the entrance to the family room, well inside the family room on the mantleplace, and the last at the top of the stairs with the sensor in open air at almost the exact same height and area as the original XIAO ambient sensor. I actually wanted the second XIAO sensor over on the mantleplace as well – but didn’t want a run wires across the house that far to do it. I’m at peace with getting different readings from these sensors versus my historical readings because:

The AHT10’s are supposed to be more accurate – and also measure humidity which I’ll use near my 3D printer later on
There’s no really good way to tape the AHT10’s to a surface and that doesn’t really tell me much about the “feeling” of warmth inside the house anyhow
The floor readings were constrained by the amount of wire I had rather than really wanting measurements at those specific locations

Just looking at the charts of the incoming data suggests that the AHT10 sensor data is definitely less noisy than the thermistor data. Then again, it might be due to the way in which I’m taking readings every minute but then broadcasting the data every 5 minutes. I’m sure no one would notice or care if I sampled the data every 5 minutes, but when the peak heating coming in from that one picture window only lasts about 30 minutes, I think I’d like to get a better sense of what’s going on minute-by-minute rather than at 5 minute intervals.

Summer Science - Testing Effects of Window Coverings on Interior Temperatures

Changing something behind the comment line from “#==================” to the same thing with one less equal sign [↩]
Way more than triple the soldering [↩]

As with many of my projects, the scope and build has changed somewhat over time. This project started with me just taking readings around my house with an infrared thermometer at somewhat regular intervals. However, this was tedious and prone to variance as I measure things by hand. After that, I started using a single XIAO board with three hardwired thermistors around our entry way. The nice thing about this kind of a setup is that I really only have to build/program one board, set it up, and then let it send data to my PC. The downside is that there’s wires everywhere – and it used up my entire stash of glorious rainbow colored ribbon cable. ¹

Practice when I work on a project is to buy replacement parts for the pieces I use up after I’m done. This way, I will still have stuff on hand for my next project. So, I’ll need to pick up more colored colored ribbon cables, small solderable prototyping boards, and replacement microcontrollers. Back in the day, I would stock up on Adafruit Trinkets, but for about a lower price and a slightly larger footprint, I can get a XIAO board with more IO ports, memory, speed, and built-in wifi/bluetooth. The little prototyping boards I’d purchased aren’t available from the same seller on Amazon, which is too bad. I really like these boards because they’re bigger than just the microcontroller, have power rails that run down the center rather than the sides and horizontal rows, and rounded corners. They’ve been incredibly convenient.

With this project, I wired up three Wemos D1 Mini boards, each to a different AHT10 temperature/humidity sensors, and shoved them into my favorite enclosure – cheap tap lights.²

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As I’ve mentioned previously, I’m just not very good at soldering – which is why I go very slowly, checking, rechecking my progress as I go. Even so, I made two small and fixable mistakes, soldering the wrong connection somewhere and later accidentally bridging two contacts. Fortunately, some things are fixable.

The construction of these little wifi sensors isn’t very interesting. Rather than run each board off of 4.5 volts from three AA batteries, I’m using 3.0 volts from two AA batteries. By not passing that 4.5 volts through the voltage regulator to bring the power down to 3.3 volts, I should be able to save enough battery life to justify running this system off 2/3 the batteries. This meant I soldered the power connectors to the end and middle battery connectors. I have a suspicion that the XIAO boards are probably more power efficient, but if I don’t use those Wemos boards for something simple like this, well, I’ll probably never get around to doing it.

In any case, I now have these three sensors throughout the house near the locations of the prior sensors. I like these AHT10 sensors – but unlike the thermistors, I can’t really get the sensor right up against a surface. Hopefully it won’t matter much. While the readings directly off the flooring and metal plate were dramatic and gave a sense of the heat that was being absorbed and released by the house, it’s the actual temperatures in the house that are what I’m after. In the meantime, I’m running both systems in parallel so I can make sure they’re both pulling in reasonably consistent readings. If so, I’ll pull down the tangle of wires, wind them up, and set them aside for the next project.

Summer Science - Testing Effects of Window Coverings on Interior Temperatures

I picked up 15 feet for $5 about 13 years ago from Sparkfun, now selling for $7. Digikey also carries it for quite a bit more, but I haven’t run the math to figure out whether shipping makes a difference. [↩]
With some hunting, you can find a set of tap lights for about $1, they include a battery holder, switch, bright white LED, attractive sturdy case, and semi-translucent top. [↩]

Tag: sensors

Repeatedly Redundant (Sensing Sensors)

Now with remote sensors