Because You Can: Linux On An Arduino Uno

October 13, 2023 by Jenny List 26 Comments

There are a few “Will it run” tropes when it comes to microcontrollers, one for example is “Will it run Doom?“, while another is “Will it run Linux?”. In one of the lowest spec examples of the last one, [gvl610] has got an up-to-date Linux kernel to boot on a vanilla Arduino Uno. And your eyes didn’t deceive you, that’s a full-fat kernel rather than the cut-down μClinux for microcontrollers.

Those of you who’ve been around a while will probably have guessed how this was done, as the ATmega328 in the Uno has no MMU and is in to way powerful enough for the job. It’s running an emulator, in this case just enough RISC-V to be capable, and as you’d imagine it’s extremely slow. You’ll be waiting many hours for a shell with this machine.

The code is written in pure AVR C, and full instructions for compilation are provided. Storage comes from an SD card, as the ATmega’s meagre 32k is nowhere near enough. If you’re having a bit of deja vu here we wouldn’t blame you, but this one is reputed to be worse than the famous 2012 “Worst PC Ever“, which emulated ARM instead of RISC-V.

Thanks [Electronics Boy] for the tip!

Teletext In Ireland, Another Broadcasting Leftover Bites The Dust

October 13, 2023 by Jenny List 14 Comments

Over the years we’ve reported on the passing of a few of the broadcasting technologies of yesteryear, such as analogue TV in America, or AM radio in Europe. Now it’s the turn of an early digital contender, as one of the few remaining holdouts of old-style teletext is to shut down its service. The Irish broadcaster RTÉ is to turn off its teletext service Aertel, which has been live in some form continuously since 1986.

Like all European countries, Ireland has had only digital TV for quite a few years now. The linked RTÉ piece implies that the Aertel service has been carried as the old-style data in the frame blanking period even when part of a digital multiplex rather than the newer digital teletext system, so we’d be really grateful if some of our Irish readers could flick on their TVs and confirm that.

In an internet-connected world it seems quaint that a limited set of curated pages could once have been such a big deal, but it’s easy to forget that for many the teletext system provided their first ever taste of online information. As it shuffles away almost unnoticed we won’t miss counting through the page numbers cycling by in the top corner as we waited for our page to load, but it’s worth marking its final passing from one of the few places it could still be found.

Teletext does pop up in a few projects here, most recently as the display engine for a game of DOOM.

Debian Bookworm Comes To The Raspberry Pi, And Wayland Is Now Default

October 13, 2023 by Jenny List 48 Comments

It must have been a busy week for the PR department at Raspberry Pi, with the launch of their latest single-board computer, the Pi 5. Alongside the new board comes something else, an updated Raspberry Pi OS version.

This is built from Debian 12 “Bookworm”, and supplants the previous “Bullseye” version. As well as the new OS base it comes with a pile of Pi-specific upgrades including an optimsied version of Mozilla Firefox. Probably most important is that henceforth (at least on 64-bit boards) its desktop will use the Wayland compositor rather than X11 to draw and manipulate windows. This is a development that has been in the works for a very long time — it must be almost a decade since the first Raspberry Pi blog entry about Wayland — so it’s welcome at last to see it.

The new tweaks as well as Wayland are supposed to deliver a much faster Pi experience, so we thought we’d break out the stopwatch and do some rough real-world tests. The bench 8GB Pi 4 here has a vanilla 64-bit Bullseye installed, so off we went to measure boot time, Chromium browser opening time, and Hackaday load time. It was time to download the new 64-bit Bookworm image and do the same. Have we just downloaded a power-up?

Both tests were done with an everyday boot, after the first-time OS set-up, and with all browser caches emptied. First up was a significant boost, with Bookworm booting in 37.14 seconds to Bullseye’s 53.5, but the Chromium opening was a little more disappointing. On Bullseye it took 7.15s, while Bookworm’s Chromium managed a more pedestrian 9.13s. The new Firefox takes only 7.95s to open. Both Chromium browsers load Hackaday in about 1.8s, while the new Firefox did the same job in a shade over 3s.

So allowing for our stopwatch reaction time and the ad-hoc nature of the test, this is a faster-booting OS, but the underlying hardware is still the limiting factor. We’re disappointed to see that there’s no update for the x86 version of the Raspberry Pi Desktop, and we hope they’ll be able to rectify this in the future.

Tiny Linux On A No-MMU RISC-V Microcontroller

October 11, 2023 by Jenny List 21 Comments

In the vast majority of cases, running a Linux-based operating system involves a pretty powerful processor with a lot of memory on hand, and perhaps most importantly, a memory management unit, or MMU. This is a piece of hardware which manages virtual memory, seamlessly giving each process its own memory sandbox in which it shouldn’t be able to rain on its neighbours’ parade. If there’s no MMU all is not lost though, and [Uros Popovic] gives us a complete guide to building the MMU-less μClinux on a RISC-V microcontroller.

The result is something of a Linux-from-scratch for this platform and kernel flavour, but it’s so much more than that aside from its step-by-step explanation. It’s probable that most of us have heard something of μClinux but have little direct knowledge of it, and he leads us through its workings as well as its limitations. As examples, standard ELF binaries aren’t suitable for these systems, and programmers need to use memory-safe techniques.

Whether or not any of you will run with this guide and build a tiny MMU-less Linux system, anything which expands our knowledge on the subject has to be a good thing. it’s not the first time we’ve seen a RISC-V microcontroller turned to this task, with a nifty trick to get round the limitations of a particular architecture.

Jenny’s Daily Drivers: SerenityOS, And In Particular, Ladybird

October 10, 2023 by Jenny List 36 Comments

As we continue on with the series in which I take a different OS for a spin every month I am afraid, dear reader, that this month I have a confession to make. Our subject here isn’t a Daily Driver at all, and it’s not the fault of the operating system in question. Instead I’m taking a look at a subject that’s not quite ready for the big time but is interesting for another reason. The OS is SerenityOS, which describes itself as “a love letter to ’90s user interfaces with a custom Unix-like core“, and the reason I’m interested in it comes from its web browser. I know that the OS is very much a work in progress and I’ll have to forgo my usual real hardware and run it in QEMU, but I’ve heard good things about it and I want to try it. The browser in question is called Ladybird, and it’s interesting because it has the aim of creating a modern fully capable cross-platform browser from scratch, rather than being yet another WebKit-based appliance.

A Pleasant Trip Into The 1990s

Part of a Linux desktop with the SerenityOS build instructions in the background, a terminal having built the OS, and the OS itself in a QEMU window. — My first look at SerenityOS after building it.

SerenityOS isn’t ready to be installed on real hardware, and there’s no handy ISO to download. Instead I had to clone the repository to my Linux machine and run the build script to compile the whole thing, something I was very pleased to observe only took about 40 minutes. It creates a hard disk image and opens QEMU for you, and you’re straight into a desktop.

When they mention ’90s user interfaces they definitely weren’t hiding anything, because what I found myself in could have easily been a Windows 9x desktop from the middle of that decade. There are a bunch of themes including some Mac-like ones, but should you select the “Redmond” one, you’re on very familiar ground if you had a Microsoft environment back then. It’s only skin-deep though, because as soon as you venture into a command line shell there’s no DOS to be found. This is a UNIX-like operating system, so backslashes are not allowed and it’s familiarly similar to an equivalent on my Linux box. The purpose of this review is not to dive too far into the workings of the OS, but suffice it to say that both the underpinnings and the desktop feel stable and as polished as a Windows 95 lookalike can be. The various bundled utilities and other small programs seem to work well, and without any hint of the instabilities I’ve become used to when I’ve experimented with other esoteric operating systems. Continue reading “Jenny’s Daily Drivers: SerenityOS, And In Particular, Ladybird” →

Raspberry Pi Reveals A Little About Their RP1 Peripheral

October 10, 2023 by Jenny List 50 Comments

The Raspberry Pi 5 is the new hotness from the Cambridge-based single board computer vendor, thanks in part to its new wonder-chip peripheral that speeds up much of its interfacing with the world. The RP1 hangs of the CPU’s PCIe bus and takes on many functions previously in the SoC, and those curious about it now have a little bit of information. Eben Upton has posted an article about the chip, and there’s a partial datasheet and a video in which the engineers talk about the chip as well.

The datasheet is intended to help anyone wishing to write a hardware driver for a Pi 5, and they admit that it doesn’t reveal everything on the silicon. We don’t expect them to put this chip up for sale on its own because doing so would enable their competitors to produce something much closer to a Pi 5 clone. It does reveal a few nuggets, though; there are a couple of Cortex M3 cores for housekeeping, and alongside all the interfaces we know from earlier boards it has, perhaps most interestingly for Hackaday readers, a 12-bit analogue-to-digital converter. This has always been on our Pi wishlist and is a welcome addition.

So, if you read the datasheet and watch the video below, you’ll learn a lot about the interfaces and how to talk to them, but not quite so much about the full workings of the chip itself. They hint that there’s more to be released, but since the Pi people have a history of not letting go of the family silver, we won’t expect the keys to the kingdom.

Have a read of our Pi 5 launch coverage.

Continue reading “Raspberry Pi Reveals A Little About Their RP1 Peripheral” →

Use Your Old SLR As A Digital Camera?

October 9, 2023 by Jenny List 43 Comments

Back in the late 1990s as the digital revolution overtook photography there were abortive attempts to develop a digital upgrade for 35mm film cameras. Imagine a film cartridge with attached sensor, the idea went, which you could just drop into your trusty SLR and continue shooting digital. As it happened they never materialised and most film SLRs were consigned to the shelf. So here in 2023 it’s a surprise to find an outfit called I’m Back Film promising something very like a 35mm cartridge with an attached sensor.

The engineering challenges are non-trivial, not least that there’s no standard for distance between reel and exposure window, and there’s next-to-no space at the focal plane in a camera designed for film. They’ve solved it with a 20 megapixel Micro Four Thirds sensor which gives a somewhat cropped image, and what appears to be a ribbon cable that slips between the camera back and the body to a box which screws to the bottom of the camera. It’s not entirely clear how they solve the reel-to-window distance problem, but we’re guessing the sensor can slide from side to side somehow.

It’s an impressive project and those of us who shot film back in the day can’t resist a bit of nostalgia for our old rigs, but we hope it hasn’t arrived too late. Digital SLRs are ubiquitous enough that anyone who wants one can have one, and meanwhile the revival in film use has given many photographers a fresh excuse to use their old camera the way it was originally intended. We’ll soon see whether it catches on though — the crowdsourcing campaign for the project will be starting in a few days.

Oddly this isn’t the first such project we’ve seen, though it is the first with a usable-size sensor.