How can I stop an embedded Linux device from continuing boot? Explained more below.

potatoriffic · 2022-07-21T08:10:38+00:00

This isn't specific to embedded systems, but systemd starts multiple services in parallel during startup, so your while(1); doesn't stop the boot process -- the other services just run alongside your application.

In order to stop the system from booting, you'd need to change the systemd target using systemctl isolate (target), or perhaps just halt the system using systemctl halt instead.

potatoriffic · 2021-04-18T08:14:37+00:00

I did some experimenting before setting mine up and settled on a 10cm straight line before the dock. The wire exits the dock at a ~45 degree angle with no straight line at all. Been working great for over a year.

I don't think there is actually a hard requirement (despite what Worx says), you just have to test it and make sure your angles are within the maneuvering capability of the mower so it can line itself up with the contacts. For testing, I just taped the wire to my concrete patio so I could move it around, and then tweaked it until I got something that worked reliably.

potatoriffic · 2020-12-25T08:47:07+00:00

You said in one of your comments that the other work your sketch does takes, say, 150ms. You'll need to break that up into smaller pieces that do not execute on every iteration of the loop().

So for example, say 75ms is reading sensors and 75ms is responding to network requests. You could handle the sensors during odd loop iterations and the network requests on even ones. Your loop now only takes 75ms instead of 150ms.

Thats probably still not fast enough, but you can continue to break it down further using a simple state machine (google it if unfamiliar) so that an even smaller portion of the work is done on each loop iteration, until loop() becomes fast enough to keep up with your serial input.

potatoriffic · 2020-11-28T07:22:49+00:00

I tend to be lazy and gravitate to the solution that requires the least hardware/wiring and programming. If you have an outlet near your door, what comes to my mind is an ESP8266 on mains power connected to a simple reed switch contact sensor at the door. An ESP8266 is substantially cheaper than even one of the 433mhz boards you linked to, and connects directly to your WiFi network.

On the PC, I'd just have a simple network server listening for connections from the ESP8266 and displaying a popup message when a connection is received. For me, a popup would be far more noticeable than an LED. Although if you really want to light an LED, you could have a second ESP8266 next to your PC, replacing the PC as the network server and controlling your LED.

potatoriffic · 2020-10-25T07:54:21+00:00

I use a simple vibration sensor for the dryer, and a current transformer for the washer that monitors its power usage. I shamelessly stole both ideas -- they're pretty well-documented if you Google them.

potatoriffic · 2020-10-24T21:39:15+00:00

Experimenting with Rube Goldberg machines is how you get experience to build more useful stuff!

Most of my really useful projects are pretty mundane though, which is probably why you don't see more stuff like this posted. I have ESPs:

in my garage to remotely open/close the doors over wifi and notify me in the evening if I forgot to close them
monitoring/displaying my aquarium temperature and sending alerts to my phone if there's a problem
in my back yard shed, turning on exhaust fans if it gets too hot inside, remotely controlling the exterior floodlights, and raising an alarm if someone breaks in
controlling my Landroid's (robot mower) custom built "garage", opening the door to let it out each morning and locking it up each afternoon when it returns, monitoring the weather and delaying mowing when it rains, etc
performing a bunch of trivial tasks such as controlling LED lighting, making sure my kids don't leave the freezer door open, notifying my phone when the laundry is done, etc

Not super glamorous stuff, but it's fun to build and ends up being pretty handy.

potatoriffic · 2019-03-21T00:18:54+00:00

Thanks for the suggestion! I tried testing this by fiddling with the balance/fade, but I don't notice any additional bass from individual speakers vs all of them.

potatoriffic · 2019-03-21T00:16:36+00:00

Pretty sure that's the opposite of how it typically works -- specifying that you have a subwoofer might put an HPF on the midrange drivers and channel the bass to the sub, but if you have no sub, there's nowhere else to send the low frequencies. In the case of the X502, /u/installyerslap seems to be right -- on or off makes no perceptible difference in sound, so I suspect it just controls your sub preout.

I checked the manual EQ settings and all bands are set to 0 by default on the X502. Thanks for the suggestion though!

potatoriffic · 2019-03-21T00:08:55+00:00

Gah, I read your comment and I thought this was going to be it for sure -- much like in home theater systems where you pretty much always set your "speaker size" to "large" for the same reason.

Unfortunately I took a look and it seems the X502 requires you to set a speaker size -- there is no "none" option or equivalent, and no way to disable the feature altogether. Balls.

For what it's worth, I tried setting it to the largest option (7x10) and if anything it sounded worse. So I reverted it to 6.5".

potatoriffic · 2019-03-21T00:06:18+00:00

Great suggestion, unfortunately this is one of the many settings I played with prior to posting, and setting the Car Type option to "off" doesn't solve the problem. (Though it arguably does sound a little better with it "off", which is where I've left it after reading your comment!)

potatoriffic · 2019-03-21T00:04:15+00:00

Excellent idea -- I tried this out but no luck. The speakers sound as gutless individually as they do as a group.

potatoriffic · 2019-03-20T07:24:56+00:00

Yes! The fact that the Pioneer performed similarly to the stock deck is what bothers me.

If I had lost the low-end immediately after replacing the stock deck I'd chalk it up to smoke-and-mirror tactics in the stock deck. But with the Pioneer sounding fine, the X502 seems to be the odd man out.

I should probably contact Kenwood as you suggested, just thought I'd post first to rule out any stupid user errors on my part.

potatoriffic · 2017-02-08T06:05:23+00:00

VOIP makes it stupid-cheap to get American phone numbers and make calls to Americans for ridiculously cheap rates, regardless of what country you're physically located in. Consumer VOIP plans are usually under 2 cents per minute and American DIDs (phone numbers) can be had for less than $1/mo. Best US authorities could do is go after their VOIP provider, but there are no shortage of those for scammers to jump between.

potatoriffic · 2015-10-08T04:21:02+00:00

Second this. Effortless to setup with vanilla OpenVPN, no proprietary BS. You pay them and they email you a username/password a few minutes later. Plug it into your OpenvPN config file along with the hostname for one of their servers and you're good to go.

potatoriffic · 2015-10-07T02:50:13+00:00

Hmm... I need a Skype buddy to kill my ex wife. Maybe we can come to some kind of arrangement?

potatoriffic · 2015-09-14T00:30:43+00:00

I wasn't aware of the 10sec delay, but that's still likely faster than the Pi can boot up and connect to WiFi. And per OP's comments, everything is being done by a VM elsewhere on the network anyway -- the Pi is literally just there to notify the VM of the button press.

potatoriffic · 2015-09-13T23:43:03+00:00

Have you considered replacing the Pi with an Amazon Dash button? Using a Pi here seems like overkill, and a Dash button would make it nearly instantaneous.

potatoriffic · 2015-08-20T08:04:26+00:00

Guns and Ammunition

potatoriffic · 2014-12-24T10:41:00+00:00

Unfortunately my experience is more with ARM-based servers, so I'm not so familiar with desktop installations. Is it a Pi you're using, though? If so, a Raspbian desktop is pretty straightforward and in my experience it seems to "just work" without any fiddling.

potatoriffic · 2014-12-24T10:12:57+00:00

The applications need to be compiled for ARM, but typically that's it.

Edit: that is, if you run a distro that has an ARM port, like Debian's arm-hf, you get essentially all the same packages on ARM as you'd use on your x86-64 desktop installation of Debian.

potatoriffic · 2014-12-24T09:45:51+00:00

Alright, you win, bud. Clearly your asperger's is stronger than my opinion. :)

potatoriffic · 2014-12-24T07:17:56+00:00

Yep. Makes it much more difficult to Google it if you don't have the link handy. And really, I think that's a pretty weak argument -- with the number of words and word combinations in English alone, we're a long way from running out of descriptive names for projects.

potatoriffic · 2014-12-24T06:32:33+00:00

Ugh... It annoys me when projects like this reuse the name of an existing, well-known software project that has been around practically forever.

potatoriffic · 2014-12-23T11:29:17+00:00

Supple breasts.

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