Yes, my little temperature sensor app works with the real Sense Hat hardware. Here’s a picture.
Temperature sense app in action
Note: that picture is taken in low light so the shutter speed is long enough to catch all of the pixels. You don’t notice the LED scanning with the naked eye, but the camera really shows it (see picture below).
When that picture was taken, it was still in a case with a fan, but it was hard to see the display and the fan noise bothered me. I took it out of the case and added a right angle extender to the GPIO connector on the Pi, so the display stands up, which keeps everything cool enough that no fan is required. I then added four risers and the lid off another old Pi case with some rubber feet, which keeps the board off the ground (and also increases the airflow).
The new look — it’s showing “25”, but the scan lines weren’t all lit when I took the picture
It actually reads a couple of degrees too high, but the accuracy of the readings isn’t all that important as long as it tracks relative temperature values. I tested it by taking it out into my garage (in January), where the temperature dropped, the display turned red, and email was sent. Yay!
Wow. I have to say I never thought I was going to end up writing Python programs for fun and (no) profit. That is until I got a Raspberry Pi Sense Hat, at least.
The specific project I’m working on is a remote temperature monitor for an unoccupied site that I’m responsible for, to allow us to react if the furnace goes out there before the pipes burst.
Given the Python library for the Sense Hat, it was basically trivial to build a program that would watch for the temperature to go outside a given range, and send email to me if it did. It took a couple of hours longer than I expected it would to write, but my excuse is that it really was my first Python program. 🙂 (Also, it seems there are quirks around getting accurate temperature readings from the SH, so I’m still tweaking the program, but it’s basically working.)
Given the 8×8 display on the Hat, I even managed to provide a continuous temperature display. 8×8 is not enough pixels to make something look good, so you end up with something like this (as drawn by the Sense Hat Emulator developer tool):
Ugly but readable. For the inquisitive, here’s the “McQ’s First Python Program” version of a function to display the digits:
###########################################################
# Display two digits on the sense hat.
# Digit patterns
digits0_9 = [
[2, 9, 11, 17, 19, 25, 27, 33, 35, 42], # 0
[2, 9, 10, 18, 26, 34, 41, 42, 43], # 1
[2, 9, 11, 19, 26, 33, 41, 42, 43], # 2
[1, 2, 11, 18, 27, 35, 41, 42], # 3
[3, 10, 11, 17, 19, 25, 26, 27, 35, 43], # 4
[1, 2, 3, 9, 17, 18, 27, 35, 41, 42], # 5
[2, 3, 9, 17, 18, 25, 27, 33, 35, 42], # 6
[1, 2, 3, 9, 11, 19, 26, 34, 42], # 7
[2, 9, 11, 18, 25, 27, 33, 35, 42], # 8
[2, 9, 11, 17, 19, 26, 27, 35, 43] # 9
]
def display_two_digits (a_number, color):
global digits0_9
black = (0, 0, 0)if a_number < 0:
negative = True
a_number = abs(a_number)
else:
negative = False
first_digit = int(int(a_number / 10) % 10)
second_digit = int(a_number % 10)
# set pixels for the two digits
pixels = [black for i in range(64)]
digit_glyph = digits0_9[first_digit]
for i in range(0, len(digit_glyph)):
pixels[digit_glyph[i]] = color
digit_glyph = digits0_9[second_digit]
for i in range(0, len(digit_glyph)):
pixels[digit_glyph[i]+4] = color
# set pixels for a minus sign for negatives
if negative:
pixels[56] = color
pixels[57] = color
pixels[58] = color
# set bottom right pixel if number is more than 2 digits
if a_number > 99:
pixels[63] = color
# display the result
sense.set_pixels(pixels)
Of course, you pass in a color for the digits to show, so when the temperature is outside the range, you can show it in red. 😉
Anyway, feel free to point out all the noob Python programming mistakes. I’m always happy to improve.
So, I realized my last post was probably a bit confusing. The reason I was seeing issues with my older posts was that I had moved them to a new WordPress install because, as it happens, I have once again moved GCW to a new machine. This time, it’s another Raspberry Pi, but this new install has a few nice things going for it:
It’s an 8Gig model. I don’t actually believe I need that much space to run a web server most of the time, but I am running quite a few web apps on it now, and depending on what was going on, I was seeing some peaks on the 4Gig one that were pushing into swap.
It’s a brand new, fresh install on SSD. The old one was still running off a MicroSD card, with the website content stored on a separate SSD. Although this gave me lots of storage for the website, it meant that the install was just that tiny bit more complex than a standard one, so I was forever fiddling with it when updating, etc.
It’s even smaller!I love the size of the finished result. Here’s a picture to give you the idea. Note the size of the ethernet jack on the side for scale.
This time around, I’ve only got 500Gig of storage for the whole install including the website, but I’m no where near hitting that limit yet, so I’m very happy.
Most of my older posts seem to have extended entries for the titles. I’m not sure what’s going on, but I suspect it’s a side-effect of one too many export/imports. Something to figure out eventually.
Update: I managed to turn it off by hiding post abstracts. I’m not sure why this suddenly started happening however. Hm…
I apparently have joined the big leagues, although it’s a bit too early to say for sure. The ping time isn’t great, but I guess it will be good enough. For comparison, here’s what I had before the upgrade:
Ping: 4ms
Down 47.5
Up: 10.4
I’ve tried GeForce Now and it’s like night and day. The game looks basically like it’s running locally now.
As you can see from this post, GCW transferred over seamlessly too.
There have been a number of interesting things happening in the Raspberry Pi community lately.
One new hotness is the RPi 4 with 8Gig of RAM, which in addition to having more RAM than you will likely ever need on a machine like this, also has a slightly updated power module that improves the behavior with some USB-C power supplies. It does mean that you can now open too many Chromium tabs to keep track of on this platform too. 😛
Another interesting update is the support for booting off of USB drives, instead of the MicroSD card. This lets you use an SSD over USB3 as your main drive, which is both much faster than the built-in MicroSD, and will have a significantly longer lifespan.
Finally, there is the 64-bit version of Raspian (now renamed as Raspberry Pi OS), which actually matters given you can get a Pi with more than 32bits of address space, but it will likely also improve performance for many tasks once the beta kinks are ironed out.
Anyway, being the RPi geek that I am, here is my latest desktop…
An 8Gig RPi4 with a 500Gig Samsung SSD, in the awesome Argon ONE Pi 4 case, which has both a temperature controlled fan (that is almost always off under normal workloads) and, believe it or not, a working power button that does a safe shutdown! This is definitely the slickest Pi case I’ve used, even if moving all the ports to the back meant making it nearly 50% larger than the Flirc case, which was my previous favorite.
Anyway, even with an SSD that cost more than the Pi and the Argon ONE case together, and the Pi overclocked to 2GHz, it’s still too slow to be a great desktop experience, but it works well enough that I was able to write this post, while watching youtube videos, with several other apps open, including LibreOffice and Gimp, so it’s definitely real.
… I have always tried to push the limits of what you can do with them. More often than not, the limits I hit were caused by one of the core tenets of the platform, that everything you need to do will be done with web apps. It turns out, this was never true, and it’s looking increasingly less likely that it is going to ever become true.
Do you spend most of your time using the web and web-centric services?
Do you have specific local programs that you absolutely need, or could most of the things you do on a computer be accomplished with web-centric equivalents — along with Android and/or Linux apps to fill in any gaps?
At some level, these two questions capture both the history, and the problem with Chromebooks. When Chromebooks were first being developed, the notion that we might end up doing everything on the web was aspirational at best and, more cynically, was an attempt by Google to force people onto a platform they “controlled”. It rapidly became clear that the under-powered, first generation devices that were being built were too limited for day-to-day use, and as the complexity of applications that were being built on the web increased, they couldn’t even handle those web apps well.
Even more telling is that, even if we believed a web-based future would eventually come, what we have actually seen is the world going in a different direction: It’s not web apps that people run, but rather mobile apps. Question two above suggested we would use Android apps to “fill in any gaps”, but it’s Android (or iOS) apps that people typically use now, even if there are web app alternatives.
So what happened? Google added support for Android apps to Chrome, and Apple is in the process of doing the same on their platform. Want proof that it’s a mobile world? Just go take a look at the relative sizes of the Google Play Store and the Chrome Web Store. Go ahead, I’ll wait…
And the funny think about all this, is that yes, Chromebooks are useful now, because they can run the applications people are using, and have large screens and input hardware that makes using those applications easier than running them on phones. Oh well.
I have been a wireless headphone geek for a long time. To give you some idea how bad it is, I have all of:
Beats Solo3
Marley Smile Jamaica
Trekz Titanium (bone conduction)
Plantronix Backbeat Fit
Soundcore Liberty Air
Corsair Void Pro (times 2)
Steelseries Arctis 7
… and that’s only the ones that I still currently use.
When the Apple AirPods Pro and Sony WF-1000XM3 came out, I tried them both and decided to pick up the Sony’s based on a perceived slightly better sound quality. Since then, I’ve seen several reviews of them both, with some level of agreement on the sound, and indications that the noise cancelling is also better.
However, my overall experience with the Sony’s has been quite poor, to the point that in retrospect I’m confident the AirPods would have been the better answer. Honestly, the UX on the WF-1000XM3 is so bad that I can’t help but think Steve Jobs would have fired any team that came forward with something in the same state.
The first issue is the companion app which, despite several updates since I first ran it, is still frequently unable to connect to the headphones, or drops the connection at some point after it gets connected, or simply crashes completely. It also includes something called “Adaptive Sound Control”, which has the following Engrish description:
The app detects your actions and [Ambient Sound Control] is switched.
Whatever this is supposed to do, the behavior manages to be simultaneously be both intrusive and not useful. I turned it off almost immediately.
The headphones themselves are also unreliable. Sometimes when you take them out of the charge case, they don’t BT connect at all. Sometimes they connect (i.e. show up as connected in the BT device list) but don’t become available as headphones (doh!). If they do get connected, the connection will later sometimes drop for one or both of them.
And speaking of “one or both”, the strangest thing about them is the way they start up. They behave a bit like they are two different bluetooth devices that notice while they are connecting that they can work together. The start up sequence has three voice prompts:
Indicate they are powered on (“Power on.”)
Indicate the current battery level (“Battery fully charged.”)
Indicate they are connected (“Bluetooth connected.”)
However, because they sync up part way through the start up, you will hear somewhere between zero and three of those messages in each ear, and by that I mean a *different* number of messages in each ear. It’s a terrible experience.
[Aside: Hey Sony, there is absolutely no reason to ever say “Power on.”. If you say any of the other prompts, we know the power is on. 😉 ]
One final comment: the WF-1000XM3 — btw, who thought that was a good name for *anything*? — are quite a bit heavier on the ear than, for example, the SoundCore Liberty Airs. I didn’t realize how much of a difference this was until I used the Airs again recently. I now find myself going back to the Airs often, even though the WF-1000XM3 have clearly better sound.
I had an old, broken 2009 MacBook Pro sitting on a shelf because I had never gotten around to trying to fix it. It had three significant issues:
It randomly kernel panicked every once in a while
It had an SSD drive in it that no longer worked
Three of the keys on the keyboard didn’t work.
Last weekend, I finally decided to see if I could get it into working shape again. To start, I took the back off and removed the failed SSD drive. The MBP is too old to run a current version of MacOS, but it still has a working HD drive, so I decided to install Linux there.
To fix the keys, I tried removing the key caps and cleaning the switches, but after putting them back together they still failed. By chance however, I noticed that if I *smashed* the key beside one of the failed ones (in frustration? 🙂 ) then the original keys would start working for a bit. This led me to pulling that other key cap off and cleaning it, and after putting it back together all the keys worked.
This only left me with the random kernel panics, so I booted the Mac into hardware test mode and let it do a full test. Even after 10 minutes of hammering RAM and CPU (with the fans screaming), there were no failures, so I chalked the problem up to either a Mac driver issue, or something to do with the now removed SSD.
For linux, I just went with Ubuntu, mostly because there was a tutorial about installing on Macs that seemed pretty reasonable. The only wrinkle was the lack of a driver for the MBP’s discrete graphics card. I went for the easy option of doing nomodeset in grub, and ended up with…
I don’t think it’s worth putting a new battery in it, but if I needed a home computer for email and web browsing this would be perfectly useful. Nice!
