Why get an expensive Pi when I have an old phone? (so.long.thanks.fish)

I feel like The Internet has this urban myth that says keeping a charged battery plugged in all the time will eventually cause it to explode and burn your house down, guaranteed.

I get that keeping a battery at 100% charge is not great for it in terms of longevity (ability to hold a charge). And it's obvious that heating the battery up by running the laptop at full tilt inside a backpack or something will turn it into a spicy pillow.

But I struggle to imagine the failure mode that reliably shows up when keeping the laptop powered on 24x7 that is never a problem for 8-16 hours of continuous use while plugged in (a very typical work day for my laptops).

Batteries degrade much faster when fully cycled repeatedly, and even then just about any laptop battery can easily make it 6+ years with low-to-zero risk of failure.

they did, with modifications

0: https://github.com/geerlingguy/mini-rack#build-showcase

In a better world we'd all have one in our homes, storing all our personal data and documents. The cloud would only be used for storing encrypted backups.

Many small businesses, kindergartens etc. could also have all their digital needs served this way.

Yes they would sometimes break down, but with the right setup, the fix would be a matter of booting a replacement from the right thumbdrive.

This let me standardize on amd64 and simplified a bunch of my deploy code.

For many (maybe even most) people they do the same thing. Some just want a HTPC, basic desktop, or small server, no GPIO needed. Raspberry Pis were definitely cheaper early on because you could actually buy boards at or near MSRP, but over time the price rose and mini PCs became cheaper.

You can make such a dongle yourself from ~any MCU dev board, but there are also productized "USB GPIO breakout" adapter boards, e.g. the Adafruit MCP2221A.

The "Pi as an SBC with GPIOs" case now only makes sense if you really, really require the Pi's compactness and/or monolithic-ness (as might be the case for e.g. ruggedized embedded systems like robots.)

Yeah, I don't disagree, but I would argue the Raspberry was always an applorange, and that's exactly what made it popular (together with the cheap price in the beginning, which made it basically an impulse buy). It brought people into microcontroller/embedded systems territory without having to actually deal with all of the stuff that made this so daunting. As you said, it is basically a normal Linux PC, just that it runs Arm and has GPIO. People who are really into electronics/embedded systems will use a proper microcontroller nowadays anyway, these have gotten so powerful and easy to use that there's really no reason for a Pi anymore. And on the other side, people who want a little server, a pi-hole, tailscale or octoprint or whatever, can just use an old used laptop/miniPC or similar. Since the Pi has gotten so expensive, I see basically no reason to get one anymore.

Suddenly the Kodi and the GPIO crowd (Arduino, ESP8266, ESP32, etc.) could work with the same board.

A new era, like the IBM PC or the iPhone. Changed computing forever.

EDIT: like other commenters noted, it seems like it made the intel NUC a reality.

Fantastic for one-off projects.

Nowadays they require cooling fans and cost absurd amounts considering the performance so there seems little point.

Most of my one off projects these days are now on microcontrollers.

At first it was a blessing that the Raspberry Pi gained popularity as a general purpose computer, not just for education and embedded applications. The additional demand and popularity brought more money and development attention to the ecosystem.

At some point, which I could never really put my finger on, this general purpose computer popularity grew so large that the embedded systems and educational aspects of Raspberry Pi seemed almost forgotten by the mainstream users. At a local in-person meetup group it was a running theme for people to brag about how many Raspberry Pis they owned for different purposes and to boast about using them for applications where they didn’t really fit. In person I’ve heard more about Raspberry Pi NAS systems (where people are always disappointed with the performance and the price of forcing a Pi into this role) or Raspberry Pi Kubernetes clusters (which mostly sat idle and could have been replaced by a single PC with more RAM).

This reached such a critical mass that it almost seemed like the mainstream discussion forgot the original purpose of the Pi and thought it was literally just another computer, but small. Most people who tried to use it for this purpose were left slightly frustrated by how it didn’t perform like they wanted a computer to perform.

So now every discussion about Raspberry Pi attracts comments about how nobody should buy a Pi when you can buy a NUC or laptop or some other used piece of hardware and it’s so much “better”. This is the right advice for a lot of people who wanted a powerful general computer but bought a Pi instead, but it’s also furthering the misunderstanding of what the Pi is for.

The real advice is that everyone should be shopping for the right tool for the job. There are a lot of cool applications for the Pi where a NUC or old laptop or phone doesn’t make sense because you actually need the compact size, the low-level I/O, or some other feature. However anyone who can put a NUC or laptop side by side with a Raspberry Pi and consider them both viable options for their project probably shouldn’t have been looking at a single board computer to begin with.

There is a parallel situation happening with the “just buy an ESP32” arguments. If an ESP32 solves your problem, you also probably shouldn’t have been in the market for a Raspberry Pi.

IMO, the problem with the Pi GPIO is that it's a collection of GPIO pins and low pin count buses for controlling peripherals, rather than a singular bus. The fact that it runs Linux without an RTOS monitor program or a sidecar of sorts adds to the problem.

Could you say more about this? What kind of setups work well? Is this really straightforward or are there any subtleties?

It makes more sense with high availability though. Their current situation seems rough.

So Nerves folks typically run Elixir on the Erlang VM. So you have the Phoenix web framework, Membrane media framework, Nx (nx_eigen) for basic inference, Emerge does well for embedded UI.

I've played around with clustering a bunch of these devices over Tailscale across my home. Opening cameras from one device and streaming to anothers display, willy-nilly. All experimental for me.

I've put Homex and Espex on them to have them integrate with Home Assistant. Feeding sensor data up or whatever I feel like.

Elixir already has a production embedded ecosystem through Nerves and web services have been the bread and butter for a long time. So you can do almost anything.

Perhaps not in the first world reality you live in, where you can buy a rpi 4 for a couple of bucks. But in third world countries they aren't readily available, and usually the imported prices exceed that of a decent PC.

You can find an old used phone for almost half the price that is still good enough for many daily processing tasks.

> You can just as well say why use an expensive PI when I have an old computer with a 1680ti and 12 gigs of ram.

That is a logical fallacy. A high end PC and an old used phone that you can buy in Ebay are in entirely different price ranges.

> Like yeah okay but what does that have to do with Pi? Entirely different device classes imo

Entirely different device classes, yeah, but both can execute the very same functions. The difference is one is much cheaper and you get 2x the processing power than the "more specialized" other. You can use both as local llm, serv ers, home automation... and even GPIO if you expose some wires from the phone.

There are exceptions, so not all phones will, but more will. I hope there'll be more time/effort put into hacking removable battery phones to accept hardwiring a PSU onto the battery terminals over the next 5 years.

I'm honestly curious to see if bypass charging is on, but it's been a while since I touched the device itself and it has been fine do far. YMMV

See: https://blog.denv.it/posts/pmos-k3s-cluster/

That's not universally true - a lot of android phones have a "bypass charging" mode where you run directly from the power supply, and indeed you can run them with the battery removed.

I once tried powering an android tablet with straight DC, turns it is EXTREMELY sensitive to slow power supplies, ie. it required a very beefy one. I had to add capacitors even to get it to work, it was really weird. But considering a battery can dish out some serious amps....

Also 4V sources are not common.

There is of course the issue that a phone uses momentarily high current when transmitting. So there needs to be beefy capacitor too.

I have done this many times, of course. Especially on Ebooks, for which you cannot find replacement superthin batteries. You use original connector and any small lithiums in parallel. Discarded e-cigarettes are good source for small lithiums.

Even using a timer to charge only every odd day still leads to the same thing.