Finishing Touches

A button on the case for the on/off switch would not be a bad idea and is not much trouble if you are happy with something basic. The solution is simply to connect a button to GPIO3 and GND and add the line dtoverlay=gpio-shutdown to /boot/config.txt. Of course, this minimal version does not resolve the problem of standby power draw, but if you have a switchable power strip anyway, this worry can also be avoided.

Besides the button, the case also has an infrared receiver and a power LED. Both are optional, but useful, especially because my existing web radio software already supports the infrared remote control. In the meantime, the push button has been replaced by a touch sensor, but the interaction with GPIO3 then only works with an inverter in the middle.

All in all, the case design consumed a lot of time, and because of the size, the Prusa MK3S 3D printer I used also reached its limits. For example, printing takes up almost the entire area of the print bed (20x25cm of 21x25cm), so I had problems with warping at the corners – the bed heater doesn't work optimally at the edges. Printing the two case parts took more than 10 hours each. Thanks to targeted test prints of critical parts, however, one print run each was sufficient for the final version.

I provide full details of the system configuration and the case models in my project repository [4], but because of the tight tolerances and matching to the available components, anyone who wants to take on the design certainly has some work ahead of them.

Software

The hardware is now neatly configured and has found an attractive home. Next, I introduce the software for the web radio, with some adjustments that not only concern the change from a 4x20cm display to the large Waveshare screen, but that also relate to basic operation. After all, the idea is not only to operate the web radio from the touchscreen in the device itself, but to use a matching remote and a fancy web interface.

The software presented here, although intended for the luxury living room appliance (Figure 7) with Waveshare's touch-enabled widescreen, also does its job independently of this particular hardware. Implemented in Python, it runs on any Linux system, from desktop to Pi Zero. With a few minor hacks, it should also be possible to run the program on Windows; the only requirement would be a working audio configuration for the sound output.

Figure 7: Raspberry Pi-based web radio for the living room system.

Before I get started with the installation and configuration, I'll take a look at some of the technical details of web radio.

The Longest MP3 in the World

Web radio, aka Internet radio, transmits (streams) a seemingly infinite MP3 file over the Internet. Instead of storing the file and then playing it back, the player accepts the stream directly and plays the audio data.

The player software can therefore be anything that calls up URLs and plays the received data directly, especially a web browser. Because virtually every radio station is now available on the Internet, you will often find a button for live playback of a program displayed prominently on the site (Figure 8).

Figure 8: Virtually every radio station today offers the option of listening in a web player.

The simplest web radio comprises a device with a browser (e.g., a retired smartphone) and a collection of links to your favorite stations. You don't even have to compile and maintain the link collection yourself because many portals [5] on the web take care of this detail [6] and also offer apps for iOS and Android. Because many AV receivers can also receive music as a Bluetooth stream, an almost complete solution in the simplest case is for the smartphone to pass the received stream to the receiver by Bluetooth.