2020-07-12
At the time of writing this post the outdoor temperature is 96F. This is according to the Google and verified by my personal temperature/humidity probe. It’s also very sunny with not a cloud in the sky. So what’s the attic temperature? I’m expecting a fairly high number due to high outdoor ambient temperature and lots of sun. Drum roll please … the system measured attic temperature is 106.1F. Not as high as I had thought Read more…
2020-07-09
In the last post I did some basic arithmetic to see if the system as designed should be able to measure 110F. This post is about verifying the physical reality to see if matches the pristine mathematical theory. To turn the VICTD into temperature in Kelvin the function is below. We know this from the previous post. $$T_K = V_{ICTD} \times 10^3 $$ Measuring the output of the probe I get a reading of 0.30111V. Read more…
2020-07-05
My home AC has been operating (fitfully) under the control of my system for a few weeks now. While doing so it has also been logging various parameters at one second intervals. I thought it would be interesting to look at the data. The first question was: what is maximum attic temperature. Since all of the data is in a Postgres database, that’s a very easy question to answer: bbb_hvac=> select max(attic_temp) as temp_f Read more…
2020-06-13
I don’t think that it’s an awe inspiring revelation that new ideas are sexy and exiting. Starting new projects, developing new designs, and shopping for and putting together BOMs is exciting. What’s not sexy and not exciting is working on the last 5% of the idea. The grinding out of the bugs and refinement of ideas and dealing with design decisions that you have no one to blame but your self. That’s where I’m at Read more…
2020-03-30
I have been working on integrating the grossly over-designed and needlessly complicated thermostat into the house. It has been mounted in the data closet (see here) and connected to the home network. All critical sensors and some of the optional sensors have been been installed. Of the optional sensors the attic temperature and the AHU supply air temp sensors have been installed. More on that later. The system is not yet controlling the house AC Read more…
2020-01-25
It has been a while since the last update and a whole lot of progress has been made. On the software side everything seems to work. For realsies this time. The full software stack compiles and runs(!) on both Linux and FreeBSD. On Linux it compiles using GCC and Clang. On FreeBSD only Clang is used since that’s the default compiler. To be fair I’ve only tested the client side stuff on FreeBSD, but as Read more…
2019-09-23
In the last post you said “The software is good shape.” I plug both boards into my workstation. Start the software. Error messages start spewing about bad checksums, buffer overflows etc. Narrow it down to a specific serial port. The serial port that’s built into the motherboard works just ducky. The port that’s an add-on card is causing problems. Start investigating. Eliminate cable, IO board, configuration, etc. Both ports work fine in text/human mode, but Read more…
2019-09-22
The hardware design is complete. All of the units that I will assemble have been assembled. The software is good shape. It hasn’t been touched in a few months, but last I worked on it it was in very good shape. The next step is actual physical assembly of the whole thing. Below are a few select pictures of the assembly progress. All taken with PotatoCam II. Where the magic happens, one of two. The Read more…
2019-09-16
Final assembly has begun. While waiting for the parts for the Beagle Bone expansion boards I started assembling the IO boards. I figures four at a time was a good idea. Find all the location on the first board and then copy that to the other boards. One component at a time of course. I was wrong. Five hours into this, my solder paste is getting dry, I’m getting anxious from sitting in one spot Read more…
2019-08-26
The VPSB (Vic’s Serial and Power Board) is functional. Fucking finally! The last function to be tested was the current monitoring of the attached peripherals and I am glad to report that it works. Not flawlessly, unfortunately. I will have to replace the 0.010 ohm resistor current sense resistor with something a bit bigger on “production” boards. Going to try a 1.5 ohm in its place. With two 3 ohm resistors in parallel current sensing Read more…