Monitoring & Logging Workshop temperature

[Bryce Walter]

(Mods: This may be a bit too Off-Topic for Workshops. Feel free to move to the Off-Topics forum if appropriate)

As a hobbyist, I work out of my attached, but unheated garage. This time of year the temperature becomes a limiting factor. 47 degrees is the critical line for me (Titebond III). There are a lot of weatherstations that could tell me the current temperature, but I wanted a solution to help predict what the temperature will be through the first few hours of cure time. I couldn't find anything out there that met my needs, so I ended up "building" my own solution.

Using a Raspberry pi device and a software-defined radio, I collect temperature & humidity data from Acurite thermometers. I have a thermometer inside my garage, and one outside. I process and upload that data for logging and visualization.

The result: https://thingspeak.com/channels/905684/

I can provide a more in-depth walk through of what I did if anyone is interested. (Requires a fair bit of IT/computer knowledge)

[Eugene Dixon]

Do the garage doors stay down throughout the data range? If they are used, how long does it take the temperature stabilize? Do you 'mark' the data logger when the doors are opened/closed?

[Bryce Walter]

It's set to display the last 5 days. I do park at least one car in the garage each night. So yes, the there's opening of a door a few times each day.

That has been one of the suprising things from the data. I don't see any noticeable temperature shifts from the doors opening.

A few things that I think factor in to that:
- The temperature probes have a plastic casing. That presumably provide some level of insulation against registering immediate/short-blips in temperature changes.
- My wife will tell you that I'm an energy cop. When it's cold, I keep the door open the absolute minimum amount of time (usually < 30 seconds). Out of a 3-car garage, having a single door open apparently doesn't lead to a massive air exchange.
-We haven't had extreme cold temps yet. The largest garage/outside temperature difference has been 20-25 degrees. I suspect super cold (0ish) weather should show a more obvious impact.

The other surprise has been how steady the garage humidity is. It hasn't moved outside of a pretty narrow range, except for when I pulled in a car when it was raining. That drove the humidity level up above 90% and took over a day to return to normal.

I'm currently not injecting events to show door open/close activity. I've considered that, but honestly would take more investment (time and money) than I personally would get value from.

[ChrisA Edwards]

I use a product called TempStick, it measures temperature and humidity and bluetooths to an app on my phone. I use it to monitor the temps in my greenhouse.

[Steven Cooper2]

That's pretty spiffy! I've been meaning to do something similar but less exciting with wired sensors, but dont really want to deal with piles of wires. I do have a couple RTL-SDR's around so something like this could be a fun little project.

Is most of what you used library based or did you have to roll a substantial amount of that side of things? I haven't picked up a raspberry pi yet and something like this looks like a good excuse.

[Jim Becker]

I have a good friend who does a lot of monitoring type things with raspberry pi devices...and his shop is about 85 miles away from where he's living. (His spouse is a pastor and their current assignment is several counties away from where their eventual retirement home and his shop is) He not only monitors things like temperature, but also now controls it since the recent installation of modern heating and cooling in both the house and the shop. He does remote video, too.

[Bryce Walter]

Steven,
I'm not a developer, so no coding. This was strictly integration/config type work.

rtl_433 does the work for grabbing and decoding the Acurite signals from the RTL-SDR device. It supports output to MQTT, so I dump that data to a MQTT broker on the raspberry pi. From there, Node-RED de-duplicates the data and publishes up to Thinkgspeak for logging & visualization.

The challenges I encountered:
-As of a few weeks ago, there was a bug in the Ubuntu Server image for the Raspberry Pi 4 device. Apparently it only affects the 1GB RAM model. Result is that the USB ports are problematic (important, since the RTL-SDR antenna is USB-based). I believe there is a fix/workaround, but I swapped to the 4GB model to resolve
-Signal strength of the Acurite broadcasts. I can receive the broadcasts through a garage door, but apparently not through a regular wall. I had to fiddle with temperature probe locations as a result. I didn't mess with gain or sensitivity levels, so there may options to improve reception through configs/settings
-Too much data. I wanted to stay on the free tier of Thingspeak. Acurite broadcasts 3 pulses of the same data every 16 seconds. Uploading all of that would quickly put me into the paying tier. I use Node-RED to subscribe to the local MQTT broker and have it publish data to Thingspeak only when the values change. Looking at my current data rates, I'd be able to support up to 15 probes and stay within the free tier.

This was my first project with a raspberry pi. I'd encourage you to give it a go, especially if you already have the RTL-SDRs. For Acurite probes, I used this outdoor and this indoors.

[Bryce Walter]

Jim,
Very cool. This project has made me realize how many opportunities there are to do fun stuff with raspberry pi's and getting into automation & remote control. I'm having to resist going too far down the rabbit hole, because that takes away my already limited time from making sawdust!

[Bruce Wrenn]

Not as fancy, but I have an Accurtite wireless in shop. Recently replaced 20+ year old unit with a new one (On sale at Walmart for $4.50.) It records high / low for each 24 hour period. As for temp swings due to door opening, it's like your fridge. You open door, but food doesn't spoil unless you keep door open.

[Monte Milanuk]

Bryce,

I for one would be *very* interested in reading more about your setup and how you got there, from start to finish. I know almost nothing about software radios and that sort of thing... most of my *nix/networking knowledge is from back in the day when I was 'into' open source stuff like Linux/BSD. Got tired of fighting it all the time, and kind of moved away. Nowadays with RPis it's a lot easier to have a functional sandbox to play around and just tinker, without having to dual-boot etc.

I've been kicking around the notion of setting up something like this, mostly 'just because' and/or to put a spare RPi to use

Have you considered putting together a page on GitHub describing the project? I know I'd be interested!

[Bud Millis]

Bryce,

I would love to see a write up on this along with some photos. I have a couple of R-Pis laying around and would like to put to use.

Very interesting.

Thanks,
Bud

[Bryce Walter]

I'll work on getting something more verbose written up this weekend and posted. Thanks for the interest

[Matt Schrum]

The result: https://thingspeak.com/channels/905684/

Love it, thank you for sharing the result. My last house I had a RasPi running the home alarm system (and corresponding web interface for remote access) and they're fun tools. Temperature logging, similar to your set up, was on my list for our greenhouse-- but then we moved and my project list got reset. I'll need to pencil some form of this back on my list for when I get free time again..