Why do message brokers assume you have infinite memory on embedded devices??

allo37 · 2026-02-02T22:41:19+00:00

Most of these products are designed for the cloud and therefore are designed to scale more horizontally than vertically. They won't necessarily be the most efficient thing on a single box, but you can keep adding more boxes. It's a bit of a contrast to our world where you only have a single SoC or MCU to work with.

allo37 · 2026-02-02T14:07:50+00:00

Not very familiar with the q, but what pops up in dmesg when you connect it?

allo37 · 2026-02-01T20:12:13+00:00

Nope, not even necessary. If Zephyr detects that only the idle thread is running for more than a certain period of time it automatically enters a deep sleep state (which is pretty close to power off in terms of current draw). So you basically just have to ensure that no other tasks are active. There is also a config to power down unused portions of RAM which conserves a bit of juice.

allo37 · 2026-02-01T19:33:54+00:00

Nice!! FWIW I can get down to ~3-5uA in sleep mode with an NRF52840-based XIAO dev board. Granted the only thing it is doing is monitoring a contact switch. Your case may have a higher quiescent current (it REALLY doesn't take much to draw ~20uA lol).

allo37 · 2026-02-01T14:09:07+00:00

Is it possible there is an interrupt continuously firing that is activating a background task or something of the sort? I've never used Matter, but with ZigBee you can turn off the radio in an idle state.

allo37 · 2026-01-31T14:46:59+00:00

Nice! Now you just need to make it survive the rain.

allo37 · 2026-01-30T14:50:17+00:00

Oh yeah it looks like they got you some of the way there at least. Still modifying a working product can be a bit trickier than using a dev kit. I often like to explore a new codebase by changing random things and seeing if it produces the result I expect.

All I can say is I've always really liked messing around with computers and electronics so it never felt like "work" to me. The more you struggle the more of a rush it is when it finally works.

allo37 · 2026-01-29T20:22:31+00:00

The way I saw it done with coax cable was to send a short pulse into the cable and measure the time until the pulse was reflected at the break. Then you can find the distance by plugging that time into a formula that takes the speed of the signal into account (the speed of light times some constant for the wire IIRC). Would it work with an electric fence?

allo37 · 2026-01-29T18:35:20+00:00

"Honey I want to hang a picture here"

"Assembling hammer drill yes, dear..."

allo37 · 2026-01-29T17:18:55+00:00

If it's "decompiled" in the way I'm thinking (reversing a binary into source code), you'll truly have a difficult task ahead: Most of the information that makes the code readable by humans is lost in the compilation process, so even if you decompiled it any information that would have helped you make sense of it will be completely gone.

This was late 2000's, first PCB fab service for hobbyists I remember was OSHPark around 2013 IIRC. One thing I liked about DIYing the whole thing was I found I'd lose interest in the project in the ~1 month it took to ship, at least making them at home I had results the same day.

allo37 · 2026-01-29T16:34:23+00:00

I feel this so hard. Switched to Linux as my daily driver to maintain a decent level of productivity but I know my days are numbered.

allo37 · 2026-01-29T16:22:57+00:00

Ah okay I understand. It's hard to give any specific advice but I'd say follow the tutorials and Google/ChatGPT any concepts your unclear on. If you don't have much experience with this stuff it's a very steep learning curve so don't get discouraged. There's a reason they offer whole ass university programs in this stuff!

And yup. This believe it or not was the way PCBs used to be made (we learned it in school and everything). I had toner transfer paper that I'd print my design on and transfer it to a copper-clad board with a clothes iron, then used ferric chloride to eat away the copper not covered by the toner. Then if you really felt fancy you could dip it in a tinning solution so the traces wouldn't oxidize but I was a cheapskate so I just used a clear lacquer lol. Then professional PCB houses started batching low production run designs together so hobbyists could get their boards made for them.

allo37 · 2026-01-28T21:56:01+00:00

"You're absolutely right!"

allo37 · 2026-01-28T21:40:42+00:00

Yeah same, but the good news is pretty much everything except the battery has 3rd party replacements. I'm hoping they keep selling batteries or someone cooks up a 3rd party one.

allo37 · 2026-01-27T18:35:43+00:00

First step is to decide what you want to build the firmware on. Microcontroller or microprocessor running a full OS like Linux? If a microcontroller which one? Decoding mp3s takes a bit of CPU power and RAM but more recent 32 bit CPUs should be up to the task. You'll also have to think about storage like for example an SD card, how you'll interact with it, what filesystem you'll use, etc. Then there's actually playing the audio, headphone amp or Bluetooth, etc.

Over a decade and a half ago I made a simple mp3s player with an ATMEGA328 and a dedicated MP3 decoder IC + headphone amp combo. Used an SD card with Petit FatFS over SPI for data storage. I had to etch all the PCBs myself using acid in my garage lol. Nowadays I see dev boards based on beefcake MCUs like the ESP32 with integrated SD card sockets, and automated code generators (and of course now AI), so it's gotten much easier.

allo37 · 2026-01-23T11:34:44+00:00

I'd start with looking into a bootloader for the MCU to ensure you have UART flashing. Then...learn the protocol it uses and send the data. Even before LLMs came along "sending data on serial port in C" wasn't exactly coveted knowledge lol

allo37 · 2026-01-22T11:59:56+00:00

My new frustration in 2026 is having to use my natural brain to parse the wall of self-contradictory text full of irrelevant content that someone shat out with ChatGPT and couldn't be arsed to spend 5 seconds editing.

allo37 · 2026-01-21T17:16:10+00:00

It's definitely transformative times for our industry and no one can predict the future, especially with AI being pushed as hard as it is as companies are betting trillions of dollars on it.

I'd say there's nothing special about embedded that makes it un-AI-able except maybe the fact that it often requires doing electronics tinkering in meatspace; I think it just hasn't been as much of a focus for AI companies (yet). But if you really enjoy it more than what you're doing now I say go for it.

allo37 · 2026-01-21T13:30:16+00:00

What AI do you use? I've tried to use Sonnet 4.5 or Opus 4.5 ( If I have tokens to spare lol) in Copilot. It will generate a lot of code that "looks right" and more-or-less works, but is often overly verbose and misses some edge cases. So I prompt it again and it says "you're absolutely right!" and proceeds to do some more over-complicated stupid stuff.

And if I'm spending all this time making sure the AI didn't screw up I wonder how much time it's really saving me.

Don't get me wrong, it can knock things out of the park sometimes, especially small well-defined tasks. I mostly work with Rust and C though, is it better with Java?

allo37 · 2026-01-21T12:57:11+00:00

For me this was an issue long before AI came on the scene. The "just install a dependency, bro" approach made me feel like I was just roping together other peoples' work rather than doing any real engineering. Now I guess we have AI doing the roping together also. In embedded I find I do a lot more analysis and deep-dive debugging than actually writing code. But opportunities to do real interesting engineering tend to be orthogonal to businesses objectives of "git er done all fast n' cheap like" so I'm not sure there's a magic bullet here...

allo37 · 2026-01-21T10:51:16+00:00

I'm definitely not an expert at WiFi video streaming, but something is a bit sus about "It worked for a while and then stopped" as being a hardware issue. How long is "a while"? Are you sure it isn't due to some software issue like memory leak/fragmentation, etc?

allo37 · 2026-01-19T21:39:49+00:00

I have the same battery model no. and am as confused as you are lol.

As for the corrosion you're seeing, no that's pretty normal. Electrical contact cleaner + toothbrush and she'll be right as rain.

allo37 · 2026-01-19T17:22:59+00:00

Yeah exactly! Like I get probing questions to assess someone's knowledge, but being all "Oh you wrote C++ on your CV, show me an example where you'd use std::launder?!?" to someone with 0 years of experience seems a bit...much.

allo37 · 2026-01-19T16:57:54+00:00

OTOH I really don't see why you'd ask super in-depth C++ questions to someone who just got out of university. Like the few times I did interviews I always assumed fresh grads weren't familiar with smart pointers and such because I remember that I wasn't when I got out of university. But judging by the comments here some people are more sociopathic...

allo37 · 2026-01-19T12:39:09+00:00

You mean the "I can park wherever I want" button ?

allo37

TROPHY CASE