Putting an Ultra-Tiny Linux Board in a Phone Charger Eventually | Hacker News Reader

Putting an Ultra-Tiny Linux Board in a Phone Charger Eventually

hackaday.com

110 pointsrbanffy49 comments

Relatedly, here's a GSM cellphone in a package only slightly larger than a normal USB plug: https://news.ycombinator.com/item?id=15676737

(2017)

So, we could fit phones inside USB connectors, 4 years ago. Nice >:(

Just slightly bigger, but one could actually build a similar thing at home literally for change coins: https://www.ebay.com/itm/284022359237 (or search for "SIM 800 module")

This one is a module that does GSM voice+SMS communication; just add a cheap GPS module if necessary, a small 8 pin uC that speaks serial, some code, a battery and voila. The problem with these devices is that they need a SIM card which I believe needs some form of registration pretty much everywhere, so unless there is some governmental screen to protect you, if you use any SIM based device to spy on others you'll be leaving behind sensitive traces useable to identify you.

Aww, if only Australia's 2G network were still up and running (it got turned down back when dinosaurs still roamed the earth :/), and 3G's getting nuked in 3 years as well.

These tiny things are so cheap!! Wow... but thinking about it, I'm not seeing SIMCom's logo in the corner, so it looks like some no-name factory somewhere has basically cloned the entire chip. Which is pretty incredible considering everything it does.

Do you guys think Linux on small SoCs are the future?

I’ve chosen the RPi 0W direction for a bathroom music player (Loodio.com) I’m working on because there are so many possibilities in the software and the goal currently is to make it so small a wall socket can support its weight. That way you never have to think about charging it, can do OTA updates and already supports so much software with Linux.

Perhaps the overhead is too high and you can already do a lot with Arduino etc?

The RPi 0W is orders of magnitude faster and bigger than the first Linux machines I used as a desktop and even the first Linux machines we used as login and mail servers for an ISP I used to run. We handled dozens of simultaneously logged in users on that machine.

So the overhead of Linux is not the issue, even with modern Linux kernels taking up substantially more space. But the overhead of any given distro may be.

You can certainly get lots of things done with a more basic device, but at this point if the unit cost of an RPi 0W works for you, it's certainly convenient to use something like that.

That said, you can do a lot smaller device and still run Linux. E.g. the smallest device I've run Linux on (and it was no record breaker by any means) had 4MB RAM and 4MB flash, and a mid 1990's low end x86 clone.

The Transcend WiFi SD-cards that I linked to elsewhere also is a good demonstration of how small you can get a Linux machine (or could, almost a decade ago)

faster and *smaller

I should have been more precise - I meant it has magnitudes more storage and memory. My first workstation had 16MB RAM (and we ran X on them) and 400MB hard-drives.

It's not an either/or thing or even a particularly new decision point. I generally just ask myself for smaller projects if an OS is justified/worth it? If so, go with a SoC or larger running an OS. If not, go with a microcontroller. All that has really changed is the area of overlap between microcontrollers and SoCs continues to grow so it increasingly becomes a requirements/preference decision vs. only one or the other being possible.

Linux has a ton of pull in this space, but you can still do a lot with thinner RTOSs on smaller, less powerful (and power-hungry) SoCs.

Yeah the fact I can SSH into the unit and install just about any services like a web server just makes me happy and I can focus on building cool software instead as if it was a fully featured server.

It’s excellent for development. Being able to have a complete development and debugging toolset inside the target environment is awesome for all sorts of reason.

One tiny problem: I don't have a wall socket in my bathroom, and I suppose many people don't. And even if they do it's likely occupied by the electric toothbrush.

The future is probably to have the CPU integrated in the speaker.

Yeah, many places there are specific restrictions on electrical equipment for bathrooms that includes e.g. specific sockets types. In the UK for example, most wall sockets in the bathroom use two prongs and are typically marked "shavers only". You can install three prong sockets that can take normal UK plugs in a bathroom, but they must have RCDs, and must be IP (Ingress Protection) rated, and the equipment to be used must also be IP rated to a certain level, depending on proximity to a bath etc.

As a result, most bathrooms in the UK only have the two-prong shaver outlets, if that.

Sure, but afaik new homes do. And the latest prototype we built was battery run but I made a lot of mistakes so I’m starting over with the raspberry and eventually making a battery version again with another mcu.

By the way, some portable speakers have a USB charging outlet which you could use as well.

When it’s time to DFM the plan is to contact a CM that makes portable speakers

I don't know where you're planning to get it manufactured, but I can recommend a CM in the UK that I used for my own Kickstarter project (vela.io) and have continued to do so for multiple rounds of reorders. I originally found them via an intro from another indie hardware maker who sells high end portable speakers. If you want a chat, send me a DM on Twitter where my username is the same.

I’m probably just going to travel down to China and meet with some factories to get rid of any middle hands. Thanks though!

No. Compared to an embedded device running targeted code, Linux will be slow, and consume more power. We're not in a post-computational scarcity period yet - responsiveness and battery life matter.

It's also much easier to handle applications that require very tight timing (examples: motor control, real-time signal processing) when you're using a microcontroller with bare-metal code or almost bare-metal with a very lightweight RTOS.

Would you call Arduino RTOS or do you normally go “deeper” for mass production?

Make sure to test your RPi 0W with the Bluetooth speaker you had in mind asap. Mine won't connect to my soundbar, which is complicating my setup for connecting my projector and soundbar wirelessly :(

Had some issues with it not showing up on iOS at first but is resolved. (First result on google) So the unit itself is now a Bluetooth speaker as well. Like so: https://www.instagram.com/p/CNsMwbhlSTj/?igshid=1wre6yuxymaz...

Just added a DAC/Amp + speaker inside.

a better idea would be to get it to replace the socket, give it a neat face plate.

Actually, you only need to have the input/output in place and plan for the wiring at building construction, because the--literally--biggest problem should be the power converter. Guess that's why you complain about weight, too.

Sure but that would raise the threshold for setup a lot for consumers. Maybe viable one day if I get a large order from a hotel chain or similar

Why not just buy something like this off aliexpress? I don't have one but I'd assume it'd be pretty easily hacked to run linux (or maybe it does already?) given it already has a camera and wifi:

https://www.aliexpress.com/item/1005002413810261.html?spm=a2...

In this case, the lede was buried a bit. The actual source article [0] talks about making this project completely open source and using components optimized for linux and networking from the get-go.

[0]: https://itnext.io/im-putting-a-wifi-router-into-a-wall-charg...

Neat.

Should combine it with power line internet for an almost completely unmonitored channel for data exfiltration.

There's the good old sdcards with wifi running Linux that seems like they'd be a good candidate for that.

EDIT: This is the one I was thinking of:

http://haxit.blogspot.com.au/2013/08/hacking-transcend-wifi-...

You can't combine it with power line internet out of nothing - you need an appliance already installed in the first place, and usually the data is encrypted over the power line anyway.

You can pick up homeplug signals from other houses if you're on the same phase. And the encryption isn't really the best.

Powerline internet to the fusebox where you turn it into 4G with another device.

You could use UPB to signal over the home wiring to another device.

https://en.wikipedia.org/wiki/Universal_powerline_bus

(Well, I guess there are several different protocols in this area, with their respective transceivers available. I used to use X-10, which has a much lower data rate.)

You'd only be able to get access to the fuse box at a very small company or at a residence. Either of which probably isn't monitoring their wifi or cellular (especially) channels.

Power line internet is very noisy in the RF spectrum.

“ I will ignore the “powered from mains” requirement for this round of the board and feed in 5V elsewhere.”

I feel this will be a challenge. The wall wart is the size it is because that’s the size of a transformer/rectifier for 120/240 to 5v. Trying to add a Linux machine to that but keep the same size is the tricky part.

I’m sure there’s something that can be done with Gallium Nitride. The chargers coming from that method are many times smaller than the contemporary. Often you can get a 90w charger where a 40w charger used to fit.

https://www.howtogeek.com/509209/what-is-a-gan-charger-and-w...

The example he shows is pretty big (but not suspisiously big) https://miro.medium.com/max/720/0*jUoQD3Udknc9b5Lx.jpg

Since there are a lot smaller chargers out there this should still be possible. https://store.storeimages.cdn-apple.com/4668/as-images.apple...

Transformers are fairly uncommon these days due low efficiency and large size.

You can build a much smaller (1-3 cm3) and more efficient system using more modern technology.

IKEA Koppla chargers would be perfect for this.

https://www.ifixit.com/Guide/IKEA+KOPPLA+Connector+(fix)/126...

I expect you could even fit a Raspberry Pi Zero inside if you replaced the charger electronics with something smaller.

Several smart plugs run OpenWRT already.

Whatever happened to SheevaPlug [1] ?

[1] https://en.wikipedia.org/wiki/SheevaPlug

They're still available in newer forms[1]. Its manufacturer, GlobalScale, is more an ODM for plug computers and provides reference devices.

There are also other smaller full package variants around. I used the Ionics PlugComputers for a PBX project ~8 years ago (no longer manufactured), and still have one of them running a PBX on debian under my desk[2].

[1] https://www.globalscaletechnologies.com/t-products.aspx [2] https://imgur.com/a/YuaLFtc

The RasPi eclipsed it in cost, usability, function, specs and performance.

Unfortunately the ulisp can run only on arduino. Otherwise it would be interesting.

But in the other hand if you just want a hacking device that can be there abd phone home, can arduino-ulisp fit the bill. Wonder.

Neat! If it’s a phone charger, instead of WiFi, why not work as a USB host and use the phone’s internet via tethering?

I assume because it would be more obvious to detect?

If it’s for a dead drop it would be more detectable if it were to connect to wifi or provide a WiFi network. Those frames can easily be detected (if that’s your threat model).

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