Kategorie: Mobile

The latest edition of The MagPi covers all the new products in depth, with detailed specifications, documentation, and interviews with the CM5 engineer. We’ve also got information on the new Raspberry Pi Pico 2 W, Raspberry Pi Hub, and Raspberry Pi Connect service.

There’s a lot of new products this month and we haven’t forgotten about the makers. This month’s mag is also packed with projects, from a Hackberry Pi to an Adventure Time electric guitar.

Priority Boarding is back!

Raspberry Pi 500 is in high demand. Subscribers to The MagPi can buy a Raspberry Pi 500 first with our Priority Boarding scheme. Take out a subscription to The MagPi and you’ll get a code via email to skip the line and get your Raspberry Pi 500 computer.

Introducing Compute Module 5 

Compute Modules make it easier for embedded customers to build custom products using Raspberry Pi hardware. Compute Module 5 puts all the power of Raspberry Pi 5 into an embeddable, programmable board that can be placed inside a development product.

Hackberry Pi Zero

This project takes an original keyboard from a BlackBerry phone and combines it with an ultra-modern Raspberry Pi Zero 2 W and 4-inch display.

Adventure Time Guitar

Raspberry Pi 5 is “the beating heart” of this impressive Adventure Time Self-Playing Guitar which features programmable buttons, custom speakers, and a touchscreen.

Get started with Raspberry Pi

It’s that time of the year when we welcome a new generation of makers to Raspberry Pi. Find out how to connect everything up, run an OS, and start using your Raspberry Pi with our guide to desktop computing and digital making.

Build your own streaming server 

This month KG builds a specialised LibreELEC-based Kodi box so our TV can talk to a server we build in issue 148.  We look at receiving those streams beyond the web interface by building a streaming media receiver box for your TV

Micro Journal

This Raspberry Pi Zero 2-based computer offers distraction-free writing Micro Journal is a modern solution with a nostalgic twist with all the charm of a vintage typewriter and delicious clicky Cherry MX keys.

You’ll find all this and much more in the latest edition of The MagPi magazine. Pick up your copy today from our store, or subscribe to get every issue delivered to your door.

We’ve been looking forward to the new Raspberry Pi Monitor for ages now – the inexpensive and lightweight display is perfect for so many uses, whether you’re in a classroom, at your desk, or on the go. We have five to giveaway, and you can enter the competition below…

Wax differs from most existing music managers in three ways. Instead of individual tracks, music is catalogued as ‘works’ – such as an album, a symphony, an opera, etc. Secondly, works are categorised by genre, but it also allows you to tag works in a way that is relevant to the genre too; symphonic works can include composer and conductor, while pop music comes with the group and title.

The final feature is that it will start playing music as soon as you’ve given it enough requirements (in the form of metadata), which you can then change on the fly.

Multi-core wonder

Wax is specifically designed for Raspberry Pi 4 because of its quad-core processor. “Wax uses one core to run the user interface, one for playing, one for ripping, and the fourth for time-consuming tasks like fetching metadata from the cloud, like MusicBrainz and Cover Art Archive,” Jeffrey says. “Many audiophiles worry needlessly that burdening a processor involved in playing a sound file can impair the quality of the sound it produces. The multi-processing architecture of Wax obviates this concern as the core responsible for playing the music is not simultaneously performing any other tasks.”

From the app you can select music starting by genre. “Works by the same composer are listed together,” Jeffrey tells us. “Likewise, multiple versions of each work are listed together. This hierarchical sorting makes it easy to survey the collection for the desired recording – possibly one that you forgot you had. Wax also provides incremental search if you already have a specific work in mind.”

Individual tracks or even the entire work can be added to the queue. You can also group tracks within a work – perhaps to represent the acts of an opera. “The other interesting feature is that the values in any column can alternatively be represented as a filter button,” Jeffrey continues. “[I can convert] the ‘subgenre’ field to a filter button by dragging the column header to the filter button area. Selecting a value with the filter button removes works from the list that do not match that value.”

Dive deeper

While the ‘gears and levers’ are usually hidden, you can enter a robust edit mode that lets you customise metadata, as well as creating new metadata for works. You can use the metadata downloaded from the online sources when creating and editing too.

Specific data is used to filter inside genres – the categories of data can be edited too. “WaxConfig is a separate program used for configuring Wax,” Jeffrey says. “Most importantly, this is where you specify genres, including their name and the primary and secondary keys. The Info page provides information about your collection, including the number of works in each genre.”

You can see an example of this in the image to the left. Jeffrey has put together a very in-depth guide on how to install and setup Wax, as well as going into more depth on how to use it. Performance on Raspberry Pi 4 is good too, especially on Jeffrey’s setup.

“I run Wax on a Raspberry Pi 4 with 4 GB of RAM,” Jeffrey tells us. “I use the NanoSound One DAC with the Argon One M.2 case. The NanoSound One DAC uses the TI PCM5122 DAC for high-quality audio output – 112 dB SNR. The Argon case makes it possible to integrate a 2TB SSD which I use for storing my sound archive.”

Even with the high-power audio hardware and no active cooling, the CPU temperature only reached 45C, with a CPU load of 2.4 (of a theoretical maximum of 4.0 due to the quad-core architecture). He even reckons a 2GB Raspberry Pi would do the job just fine.

“Wax makes it easy to find and appreciate the music I want to hear,” Jeffrey says. “Finding a recording of a specific work was often hard and always inconvenient when I had to sort through thousands of LPs and CDs. With Wax, I can make a selection from the comfort of my listening position. I sacrifice nothing for this convenience because Wax presents all the information I need to appreciate the recording — artist names, for example — and I am able to explore further, as I used to do by reading record jackets or CD liner notes, by accessing Wikipedia and liner notes in Wax from the comfort of my listening position. Instead of a wall full of recordings, my entire collection now fits in a tiny box powered by a Raspberry Pi.”

“I love the idea of using bumper stickers as a form of self-expression, but I got to thinking about how ‘permanent’ they are, and how my own style, mood and taste tends to change relatively quickly,” he says. “I wanted to see how I could resolve those things – could I make a bumper sticker that was always up to date? Would it still be interesting if it wasn’t permanent?”

On track

Figuring a changeable bumper sticker would be both practical and fun, he initially decided to experiment by connecting a Raspberry Pi Zero 2 W computer to a 5-volt HDMI display before working out a way to gather and share information about the song he was currently listening to in near real-time. He figured the best method would be to connect the Raspberry Pi device to the internet and make use of the online music service Last.fm. “It’s a ‘scrobbling’ tool that you can use to keep track of everything you listen to, regardless of where you’re listening from,” Guy explains.

By connecting Spotify to his Last.fm account, Guy had a way of grabbing details about his most recently played tune. Raspberry Pi could then pull that information and send it to the display for others to view. Since he wanted his project to look like a bumper sticker, this entailed creating an easily updated graphic – one with black text on a yellow background – that could be easily updated with new details – and Guy came up with the idea of using an image file that could be produced and rendered just before it was shown.

To enable this, Guy turned to a social website called Val Town which allows developers to code in the cloud. He wrote a small chunk of code – referred to as a val – that would access and fetch his Last.fm profile to gather details of the last song he was listening to. He then, with the assistance of Val Town’s AI, wrote another val to use a Javascript HTML5 canvas library to lay out the bumper sticker using the information gathered. This involved a lot of trial and error to make the text fit correctly, but he was able to successfully create, export and display a PNG image without any manual intervention.

Driving forward

With the nuts and bolts of the project in place, it was time to start refining. “I always start with components I already have or already know how to use,” Guy says. “I then quickly get as close as I can to a finished version, and then I see if there are any deal-breakers or cheap and obvious ways to improve the design. I find that momentum, as well as the ability to see and feel a project early on, really helps me stay on track, even if I know I’m going to have to revise things.

Given the idea was to create a device that looked as much like a real bumper sticker as possible, Dupont swapped out the display for an 11.3-inch strip LCD. “Size, shape, and readability came before anything else,” he explained. Figuring he’d be drawing power from a 12-volt car battery, he also grabbed a couple of breakout connectors and a buck converter to knock the power down to five volts.

Initial plans to connect the Raspberry Pi computer to the internet using a hotspot on his phone were revised as well. Dupont realised that he’d need to manually connect Raspberry Pi to the hotspot every time he got into his car and he knew, in his heart of hearts, that he would eventually tire of doing this, causing him to eventually consign the project to a drawer. To avoid this situation, he utilised a Particle Baron IoT development board which he also happened to have lying around.

“The main advantage of the board versus using the phone as a hotspot is that I never have to touch it or remember to turn it on,” he says. The board connects to Raspberry Pi and uses cellular data, the bonus being there are no monthly fees. The data is limited in quantity, but there’s more than enough for Guy’s intended use which makes for a perfect fit. With everything working, it was then a case of installing it, which required a spot of in-car wiring – and some dismantling of the vehicle’s interior panels.

The right path

The Raspberry Pi and other components were affixed to the back of the display panel which was also fitted with magnets to allow the device to be easily secured to the back of the car. For a neat finish, the device was placed in a heat-shrink sleeve that happened to be the perfect size. A bit of cutting was then required to allow the screen to show through, and Guy used some glue around the cuts for weatherproofing.

It works well. Powered by the car battery as soon as the vehicle is turned on, it immediately connects to the internet, grabs the required information and displays it. “Honestly, everything went pretty smoothly with this build,” Guy said. “It’s funny, but the thing that held me up the most was trying to figure out which HDMI settings would make this oddball display show what I wanted it to!”

Guy particularly likes the fact that it’s entirely automated so he always knows that it’ll be displaying his songs when he tootling down the road. “It lives with the car, which also means the sticker continues to work even if my wife is driving,” he laughs. “I’m afraid to ask whether she thinks that’s a bug or feature!”

“Using a Raspberry Pi Pico, a light dependent resistor (LDR), a breadboard, some DuPont cables, and tape, I automated the famous Google T-Rex game,” Bas explains. “The LDR detects differences in analogue measurements whenever it senses cacti, which are always dark-coloured and appear on the same plane. The analogue-digital converter [ADC] port of the Pico measures each passing cactus ten times per second. After a 0.2-second delay, the Human Interface Device [HID] library simulates pressing the ‘up’ button on the keyboard, making the T-Rex jump at the right time.”

For Bas it was a fun way to show people he teaches and trains how the HID libraries work in code: “I’ve found that simulating single or multiple key presses with embedded processors stimulates the creativity and inventiveness of training participants,” he tells us.

See the light

Raspberry Pi Pico was the obvious choice for Bas. “[It’s] easy to obtain, very cost-effective, and supports MicroPython, CircuitPython, and Arduino C++,” Bas says. “It has a small form factor, can be easily soldered onto a prototyping board using castellated connections, or placed into a breadboard using headers. Personally, I like the Pimoroni Pico Explorer Base for prototyping, as it includes a breadboard, LCD screen, buttons, and breakout connectors. I especially appreciate the MicroPython and CircuitPython capabilities – they’re easy to explain to students, powerful, [and have a] wide range of libraries.”

The build itself is fairly simple – an LDR is placed in front of the screen, with tape acting as ‘blinders’ to stop other light interference. A pull-up resistor was used to stabilise the measurements too.

“The program displayed the measured [light] values in real time, making it easy to define and adjust the threshold values to trigger the T-Rex’s jump,” Bas further explains. “I stored the delay time for simulating the ‘up’ button press in a Python variable, allowing for easy adjustments through Thonny.”

Jumping ahead

What’s next for the T-Rex Jumper? “I have various future plans for these types of educational setups,” Bas says. “I’m always excited when participants in my trainings come up with creative ideas for using HID functions in combination with sensors and actuators, as it means I’ve succeeded in educating them about computer science and improving their digital literacy. Personally, I find it very rewarding to develop and create accessibility tools for people with disabilities, as they can greatly improve quality of life and make a meaningful difference.

Speaking of the creative ideas they came up, here’s just a few: automatic typing poem generators, pedal-based keyboards, automated testing tools for user interfaces, automatic swiping of dating apps… the list goes on.