Idly Wondering – RPi 400 Keyboard

A couple of days ago, I noticed a new release from the Raspberry Pi folks, a "$70 computer" bundling a Raspberry Pi 4 inside a keyboard, with a mouse, power supply and HDMI cable all as part of the under a hundred quid "personal computer kit". Just add screen and network connection (ethernet cable, as well as screen, NOT provided).

Mine arrived today:

Raspberry Pi 400 Personal Computer Kit

So… over the last few months, I’ve been working on some revised material for a level 1 course. The practical computing environment, which is to be made available to students any time now for scheduled use from mid-December, is being shipped via a Docker image. Unlike the TM351 Docker environment (repo), which is just the computing environment, the TM129 Docker container (repo) also contains the instructional activity notebooks.

One of the issues with providing materials this way is that students need a computer that can run Docker. Laptops and desktop computers running Windows or MacOS are fine, but if you have a tablet, cheap Chromebook, or just a phone, you’re stuck. Whilst the software shipped in the Docker image is all accessed through a browser, you still need a "proper" computer to run the server…

Challenges using Raspberry Pis as home computing infrastructure

For a long time, several of us have muttered about the possibility of distributing software to students that can run on a Raspberry Pi, shipping the software on a custom programmed SD card. This is fine, but there are several hurdles to overcome, and the target user (eg someone whose only computer is a phone or a tablet) is likely to be the least confident sort of computer user at a "system" level. For example, to use the Raspberry Pi from a standing start, you really need access to:

  • a screen with an HDMI input (many TVs offer this);
  • a USB keyboard (yeah, right: not in my house for years, now…)
  • a USB mouse (likewise);
  • an ethernet cable (because that’s the easiest way to connect to you home broadband router, at least to start with).

You might also try to get your Raspberry Pi to speak to you if you can connect it to your local network, for example to tell you what IP address it’s on, but then you need an audio output device (the HDMI’d screen may do it, or you need a headset/speaker/set of earphones with an appropriate connector).

Considering these hurdles, the new RPi-containing keyboard, makes it easier to "just get started", particularly if purchased as part of the Personal Computer Kit: all you need is a screen if the SD card has all the software you need.

So I’m wondering again if this is a bit closer to the sort of thing we might give to students when they sign up with the OU: a branded RPi keyboard, with a custom SD card for each module or perhaps a single custom SD card and then a branded USB memory stick with additional software applications required for each module.

All the student needs to provide is a screen. And if we can ship a screensharing or collaborative editing environment (think: Google docs collaborative editing) as part of the software environment, then if a student can connect their phone or tablet to a server running from their keyboard, we could even get away without a phone.

The main challenges are still setting up a connection to a screen or setting up a network connection to a device with a screen.

> Notes from setting up my RPi 4000: don’t admit to having a black border on your screen: I did and lost the the desktop upper toolbar off the top of my TV and had to dive into a config file to reset it, eg as per instructions here: run sudo nano /boot/config.txt then comment out line: #disable_overscan=1

Building software distributions

As far as going software environments to work with the RPi, I had a quick poke around and there are several possible tools that could help.

One approach I am keen on is using Docker containers to distribute images, particularly if we can build images for different platfroms from the same build scripts.

Installing Docker on the RPi looks simple enough, eg this post suggests the following is enough:

sudo apt update -y
curl -fsSL get.docker.com -o get-docker.sh && sh get-docker.sh

although if that doesn’t work, a more complete recipe can be found here: Installing Docker on the Raspberry Pi .

A quick look for arm32 images on DockerHub turns up a few handy looking images, particulalry if you work with a docker-compose architecture to wire different containers together to provide the student computing environment, and there are examples out there of building Jupyter server RPi Docker images from these base containers (that repo includes some prevbuilt arm python package wheels; other pre-built packages can be found on piwheels.org). See also: jupyter-lab-docker-rpi (h/t @dpmcdade) for a Docker container route and kleinee/jns for a desktop install route.

The Docker buildx cross-builder offers another route. This is available via Docker Desktop if uou enable experimental CLI features and should support cross-building of images targeted to the RPi Arm processor, as described here.

Alternatively, it looks like there is at least one possible Github Action out there that will build an Arm7 targeted image and push it to a Docker image hub? (I’m not sure if the official Docker Github Action supports cross-builds?)

There’s also a Github Action for building pip wheels, but I’m not convinced this will build for RPi/Arm too? This repo — Ben-Faessler/Python3-Wheels — may be more informative?

For building full SD card images, this Dockerised pi-builder should do the trick?

So, for my to do list, I think I’ll have a go at seeing whether I can build an RPi runnable docker-compose version of the TM351 environment (partitioning the services into separate containers that can then be composed back together has been on my to do list for some time, so this way I can explore two things at once…) and also have a go at building an RPi Docker image for the TM129 software. The TM129 release might also be interesting to try in the context of an SD Card image with the software installed on the desktop and, following the suggestion of a couple f colleagues, accessed via an xfce4 desktop in kiosk mode perhaps via a minimal o/s such as DietPi.

PS also wonders – anyone know of a jupyter-rpi-repodocker that will do the repo2docker thing on Raspberry Pi platforms…?!

Author: Tony Hirst

I'm a Senior Lecturer at The Open University, with an interest in #opendata policy and practice, as well as general web tinkering...

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