Why get an expensive Pi when I have an old phone?

Nowadays, I just get old laptops with broken screens and take the mainboard out. They are dirt cheap, often even have 16GB of RAM, you can just dump pretty much any linux on them and they are usually way faster than Pis.

The boards are of course bigger, which I guess will be a non-starter for many. They'll also require active cooling unless you downclock them considerably. They often also require more power, although many mainboards can be configured down two a few watts of power consumption, depending on what peripherals and speed you need.

Yeah, it's more work than just getting a Pi, but given the current prices, it makes sense for me.

This is the main issue:

> The open question is supply. Finding two good used phones is easy; finding a few hundred matching ones, with healthy batteries and predictable camera behaviour, would take more work. I feel increasingly confident that it’s possible.

RaspberryPies and such are commodity hardware. You can buy one, two, ten, twenty, a hundred, and it just scales along. All of those devices will, barring perhaps a few dead-on-arrival ones covered under warranty, just work out of the box.

A used smartphone will have issues which can vary from device to device, so scaling that would take a very dedicated refurbishing setup where the quirks are ironed out (and the unsalvageable ones discarded).

I would also expect that you are starting out at the other end of the bathtub curve: with new devices you will have a few that fail soon after unboxing and using them a bit, and then they will run fine for years until you start hitting the other end of the curve and wear-related faults pop up. With old cheap phones you would start out at that side of the curve, so if you buy one hundred of those, a bunch will fail at various points soon after deploying them.

The cost of that unpredictable behaviour seems high to me. So much so that I wonder if it wouldn't be cheaper to buy a lot of unsold stock of a certain type of budget smartphone from two or three years back. Those devices could run fine as long as they aren't connected to the internet directly.

I have recently taken to gathering old phones and putting Nerves on them (Nerves packages up the Erlang VM into a mainline kernel to run on a variety of devices). I got inspired by a talk by Marc Lainez at Goatmire who had put it on a variety of exotic devices (e.g., a Wii).

I am by no means an expert at this, but starting of with a device on the Postmarket OS list and Claude, you can get a lot of these old devices working with mainline Linux and nearly all drivers. The newer devices are a bit harder, but if you go back nearly a decade, they're very easy to get working.

So far I have repurposed a Fairphone 3, Nexus 5, Galaxy S20, and Galaxy Tab 3.0 7". All of them (except the s20) with all drivers working compared to stock. Others have done a lot too: https://github.com/mlainez/awesome-nerves-systems

For DIY projects you can use host USB, or get one of the Adafruit FT232H type boards for GPIO pins.

To a degree, I see the author's point. But there is a catch for me: I have a few older phones and the reason why I generally prefer Pi over an old phone is the OS. If I could get a full-fledged linux on a phone, I don't have a big reason to look at Pis: I don't need the gpio in almost all cases. For most phones however, this is not only not straightforward but in 99% of cases not possible at all.

> Why get an expensive Pi when I have an old phone?

Because the pi has a maintained kernel and a userspace I don't have to fight.

Reasons to get a Pi: GPIO support, software support, OS updates, free root & bootloader, more flexibility and customizability, extensive documentation and support, consistency, simplicity, more ports, battery optional.

Used phones are good for tinkering, especially for "display with sensors and battery attached" usecases, but there are still plenty of downsides. And unfortunately Linux on phones is just not ready for primetime, last I checked.

I shudder with horror when I think of all the good hardware that ends up in landfill every day, due to "no longer supported". It's absolute lunacy!

You could consider getting an older flagship phone perhaps 2022-2023 and have a strong portable device with a decent amount of compute power and not to mention ram. I'm starting to believe that these devices are under utilised and we will see some interesting applications using either with AI or without.

I particuarly think the economics of this are interesting, if you take the one plus 11 you can get one for around £200-250. The CPU is very capable and the alternatives are a PI 5 or N100. You get 16b of ram, a screen, gps, bluetooth a camera... the list goes on.

These devices could really shine as edge computing devices and I believe they are overlooked.

There are a few issues with Android devices. I have 2 Android phones lying around in my rack, as well as an Android tablet that I use as a dashboard.

1. Batteries swell over time. Replacing them is easy, but it's still harder than changing one inside a UPS hat. Most phones won't even start without a battery.

2. Software support will be awful. Maybe you'll get lucky and your device will be able to run postmarketOS.

3. There's no modularity, you're stuck with the full package. Don't feel comfortable having a camera or a microphone on a device with no security updates? Too bad, there's not much you can do about it.

Don't get me wrong, if you understand these risks, are fine with them, and Android devices cover your use cases — that's great, go for it! I just find SBCs with decent software support to be a better option for general projects.

I'm a big fan of the esp32. I needed a sensor to beep when a board came down a conveyor, and an esp32 with "VL53L0X Time-of-Flight Ranging Sensor Flight Distance Measurement Module" and a buzzer works perfect for about $10 in parts. Minus the 3d printed box and articulated arm to hold it the right distance away. Call it $10.25.

Rooting or flashing a modern phone is pain in the ass. Ideally the battery needs to be replaced with a 3.7V PSU (and BMS must be salvaged without cutting the battery accidentally). And for old phones it either old linux kernel, partially unsupported hardware or fork maintained by handful of hackers for free.

I guess laptops are way easier: more upgradeable and repairable, don't require unlocking mostly, battery can just be thrown away and it works with its native PSU. Just need to make sure power won't go out. And it is bulkier, though maybe less susceptible to overheating.

The main reason is that they are one of the few ARM computers sold with a pre-installed officially supported GNU/Linux distribution, at affordable prices.

Even with the prices increases that the PI has suffered, there no systems of vendors like Tuxedo, or System 76, at similar price point, with ARM support.

Well that's because for the Pi you have GPIO. If you just want to run homelabs or software only stuff, why not go for ITX motherboard with just in time components

Because big tech decides what you are allowed to run on your phones

I recently used Termux on a 7 year old low-end android to run a WordPress site with sqlite db and a golang sse pubsub service at a conference, via cloudflare tunnel, with dozens of people connected and doing some realtime collaborative stuff. Worked perfectly.

It was vastly more powerful than the old RPi 3 that i have, and significantly easier to work with given the screen, keyboard, wifi etc...

Recently did this with a few old Android phones I had lying around, now they are three k3s nodes added to my existing homelab, 24 cores and 30ish GB of RAM, battery limited to 80%, running vanilla debian apart from the custom kernel build

https://github.com/crazynucfan/phone-nodes

Nice thing about RPI is gpio, that can be used to configure the rpi with jumpers. All you need is a script that checks gpio state on boot and run scripts depending on jumpers placement. So you can get desired services started, configs applied etc without even connecting to the rpi.

This isnt new and has a major flaw. Phones are not made to be continously charged. You have to find or tinker your own solution to power it without battery which is more cumbersome than just getting off the shelf used hardware in the raspberry range.

Depending on what you are trying to do one of the biggest problems with repurposing old mobile stuff (including laptops) is that when they are repowered they need manual intervention to get back to business.

In other words if the power goes out you need to physically be there to get the device running your always on stuff.

I guess in general, the development experience on a Pi is much better, because it’s made to be tinkered with, right? In the other hand, Android phones are also nicely hackable. I’d just guess that for beginners, it’s much easier to install the Raspberry IDE and plug in the Pi (as opposed to learning how to connect and develop for an Android phone). But yeah, for pros or vibe coders, an Android phone might be the right or even better choice. And it’s great that Android phones can therefore be used a little longer before landing in a landfill.

Underrated bit: it has its own LTE modem and battery. Makes a decent watchdog for when the router or power dies and the Pi goes down with it.

The top comment should be that without opening the case and wiring in the power directly (not easy) for such old phones THIS IS DANGEROUS. The battery, when under load and plugged in the whole time, can and will swell and explode somewhere in the future.

Pis are too expensive. I just picked up a new Bosgame AMD 5300U 4/8 core 8 GB 256GB SATA SSD, 2.5 Gbx2 NICs, 2x SSD slots, for $199 on Amazon. Great OpenWRT/Proxmix/Mini-NAS. 8 watts idle.

Phones are cheap for what you get, but problems arise when you try to add something. Driving LEDs is the start. So how do you do that? Via a cloud service? How do you add an air monitor or servos? The pi and esp32s have an ecology of add-ons and a community to support you. Sure that could be built around a rooted phone, but it would take years.

>Why get an expensive Pi when I have an old phone?

>I’ve unlocked and rooted the Redmi

Herein lies the issue. I don't know fuck all about phones. I don't want to. They are engineered to keep me out, and that is a pain in the ass I don't want to deal with when doing hardware work. I want to own something that works the second I get it and doesn't fight me the entire way. Sure, I could let an LLM guide me through it or even do it for me, but why bother when the whole point of the hardware is for me to fuck off and use it as a subscriber to the OEM and carrier? This is tedium, removed by further spending. Not to mention documentation - what bullshit is the OEM hiding in their board or firmware thats going to ruin my day? I'm sure that some of these devices are great for reuse as a self contained server with media and modem, but is my old phone going to do this?

I'm not gonna spend $50 on ewaste to try to do something unless I want to use that ewaste (old keyboards, old toys? :3). Old phones are a non-sequitur because, again, they're engineered to keep me out.

I tried this once - with a little "fleet" of phones running 24/7 serving things. But it turned out that phones do not really like running 24/7 doing something. Eventually they started failing in various ways.

This is valid for one off projects but if you want something that can replicate/scale and easily integrate into a product then RPi or Jetson boards are great

Old phones are fine if you want to tinker but are a nightmare to try and actually 'do' something with. It sucks and shouldn't be the case but here we are.

Even better are old smartphones with Sailfish OS, Ubuntu Touch or PineOS - they are based on proper Linux with full control, not crippled like stock Android, unless you flash it (if you can).

Depends on what you want to do. In terms of ram and CPU I understand but if you want HDMI, I/O... And lot of documentation about existing projects, troubleshooting....

Locked bootloaders mostly

You can also find new prepaid phones for 50$ each. Just don’t activate them.

Brings back fond memories of running torrents with Transmission 2.84 on my old iPhone 4 with Cydia.

Nowadays I dumpster dive for old computers and parts to Frankenstein together what I can with Debian as headless servers.

One man's trash is another man's treasure, repurposed to sail the high seas.

Arrrr!

Not as a knock to the author but I feel like this is a wildly optimistic / simplified take. The type of audience pis serve is either industrial as part of a product or process or tinkerers that often want to follow some set process like installing retroarch.

Not to mention not all phones are hackable, they might not have the gpio or software you want or ecosystem (I’m quite fond of the Poe hats for example) and frankly if you’re buying a pi you’re obviously not the person who has the perfect hackable phone lying around or otherwise can easily source one

Thats a great read. I explored similar things with my rooted phone. Samsung galaxy m30s. Wrote something on it as well on what I did, may be you will also like this type of experimentation?

https://nimitbhardwaj.github.io/posts/hermes-agent-rooted-an...

On a similar note, old smartphones (depending how old of course) are way more powerful than a Raspberry Pi. You can turn them into a Kubernetes cluster [1].

[1]: https://blog.denv.it/posts/pmos-k3s-cluster/

Hey, I can answer that! Because me and my family have always had Verizon and when I recently went through alllllll the devices I have ever owned, I would need to go back to circa 2010's Galaxy S7 to be able to get a rooted device, which as Claude keeps reminding me, "isn't what I want, but might be good enough"....

Raspberry PI's don't give me near the struggle and I never dumbly signed a contract that I didn't really own the device I was purchasing (that I am completely aware of)

I was thinking about using my old phones with something similar, but I'm worried about battery. When permanently connected to charger, won't they swell, start fire or something like that after longer(er) period of time?

I too have a bunch of cheap android phones of diverse vintage lying around.

Some are bought with US carrier locks - never activated or unlocked. Any chance they can be unlocked with today's tools and not dumped into ewaste.

There are a few simple projects for home automation i have in mind but the rooting felt like a daunting task.

Well if you need cameras and GPS, then 6+ year old phones/tablets are obviously the cheapest way to do this in just about any country.

But a new pi is just a bad deal for anything right now.

What are some useful things you have built using pie? Which you use maybe on a daily basis.

Yeah, people mostly just buy things to satisfy their wants. the PI sells because its the more reliable, low-friction option for a lot of use cases,even if an old phone is technically stronger and cheaper

Are you gonna open-source this so others can also benefit?

I also keep using old android phone but the battery dies every few months if you keep plug-in power cable.

Why get an expensive Pi when you can get a cheap 1L PC / tini-mini-micro or SFF pc? Especially if you don't need GPIO pins?

My blog article about this: https://louwrentius.com/the-raspberry-pi-5-is-no-match-for-a...

What about GPIO support and Raspberry Pi OS updates?

Really? That’s the takeaway?

Sure, CPU wise an old phone can do the same job, but not the GPIO.

But hey, thanks AI delusion , even a fucking raspberry pi is now a purchase I gotta think 3 times about before pulling the trigger.

...or a new phone!

You can get a cheap Tracfone for like $20, never pay for the subscription, and run termux on it.

kernel wont get updates, no IO, no ports.

Need to fuck about pretty much per phone model,rather than install Debian, unattended-upgrades and forget about device for 2 years

For me if I don't have a need for the GPIO pins, it's "why get an expensive pi when I can get a used ex-corporate small form factor quad core, intel core i7-something desktop PC with 16GB of RAM and a real SSD"... For like 150 bucks on eBay. RAM apocalypse and price of equipment has affected this a lot (these used to be like 90 bucks depending on era of core i7), but they're vastly more useful when a general purpose x86-64 linux is installed on them. Or even just put proxmox on it and then various things inside that.