Xojo Web is an excellent way to expose the features of your electronics projects without having to attach any screen to them. It’s never been easier to build a Web GUI for your smart clocks, drones, POS, domotics, robots or just some automation services. Thinking about building a solar powered server to automate your tweets? Why not!

If you prefer, you can just expose a Web API instead that can be remotely consumed from another device.

What Raspberry Pi boards support ARM 64-bit Linux OS?

• Raspberry Pi Zero 2
• Raspberry Pi 3
• Raspberry Pi 4
• Raspberry Pi 400

Preparing your Raspberry Pi

The easiest way to get your operating system ready is by using the Raspberry Pi Imager.

At the moment of writing this article, it selects the 32-bit flavor by default. If you have one of the supported boards, go ahead and try Raspberry Pi OS (64-bit) or Raspberry Pi OS Lite (64-bit). The later won’t include any desktop environment, you’ll have to access by SSH.

Select your SD Card storage and press on Write. Optionally, if you want to set a hostname for your board, enable SSH, or even configure your Wifi, press on the gears icon.

In just a few minutes you will have a ready to boot SD card for your Raspberry Pi.

Remotely debugging your projects

This is one of my favorite features of Xojo.

In your Xojo installation Extras folder, you will find a “Remote Debugger Console” and “Remote Debugger Desktop”, that also works for your Linux 64-bit OS.

Depending on which flavor of Linux you’ve selected in the previous step, send the Console or Desktop ZIP to your board, run it and configure the settings.

Inside Xojo, go to Preferences and press on the Debugging tab.

That’s it. Now you will be able to remotely run and debug your applications. Add a few breakpoints and the execution will stop as soon as it reaches it, allowing you to explore the current state.

Deploying the final version

Once you’re ready to build the final version of your application, all the wires attached and components soldered, the last step is to “Deploy” your application.

There is a tutorial covering this step in detail: Deploying Web Apps on Linux.

If you create a Raspberry Pi project, please make sure you open a Forum thread. The Xojo community loves seeing this kind of projects!

What will you build?

Ricardo has always been curious about how things work. Growing up surrounded by computers he became interested in web technologies in the dial-up connections era. Xojo has been his secret weapon and language of preference since 2018. When he’s not online, chances are he will be scuba diving … or crocheting amigurumis. Find Ricardo on Twitter @piradoiv.

sudo apt-get install libunwind8

The Raspberry Pi OS (Raspbian) does not automatically update itself. Since it is always a good idea to keep your Pi up to date, you can do it easily from Terminal using these commands:

sudo apt-get update
sudo apt-get upgrade

To learn more about Raspberry Pi and Xojo:

• Getting Started with Raspberry Pi
• Programming the Raspberry Pi with Xojo book

And don’t forget, you can build Console and Desktop apps for Raspberry Pi with your free Xojo license.

I decided what would work for me is to have demo app automatically launch when the Pi boots. This would allow me to demo the app and project anywhere just by plugging in the Pi. There are several ways that a Pi can automatically start an app. After doing a bit of Google research I decided on this approach:

1. Open the /etc/rc.local file (you’ll want to use sudo):

   sudo nano /etc/rc.local

2. Add lines to automatically start the app you want. My app was a console app that used GPIO, so I added these two lines:

   export WIRINGPI_GPIOMEM=1
   /home/pi/Documents/Xojo/LCDPanel &

For reference, this is my rc.local file contents:

#!/bin/sh -e
#
# rc.local
#
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
#
# In order to enable or disable this script just change the execution
# bits.
#
# By default this script does nothing.

# Print the IP address
_IP=$(hostname -I) || true
if [ "$_IP" ]; then
 printf "My IP address is %s\n" "$_IP"
fi

export WIRINGPI_GPIOMEM=1
/home/pi/Documents/Xojo/LCDPanel/LCDPanel &

exit 0

You can develop and build console and desktop apps for the Raspberry Pi using Xojo 2019r1 or later for free.

Download Xojo today and get started!

Fun times at XDC:

Download Xojo today and get started with this simple music player app for your Raspberry Pi that can play mp3 and aac (m4a) files from a folder.

By default Raspberry Pi sound output is sent to the HDMI port. There is also a headphone port that can be used for sound output to make it easier to hook up speakers. To switch between the sound outputs, you use this command at the Terminal:

sudo amixer cset numid=3 1

Other values you can use are: 0=auto, 1=headphones, 2=HDMI.

Create the Project

Create a Desktop project and call it MP3Player. For controls, you will add three buttons and a label to Window1. Arrange them to look like this:

Change the name of the label from “Label1” to “NowPlayingLabel” and make it as wide as the window.

Now add these properties to keep track of the song files to play and the currently playing song sound:

CurrentSong As Sound
CurrentSongIndex As Integer
Songs() As FolderItem

The music files are loaded as Sound objects and the CurrentSong property is the song that is currently playing. The Songs() array is an array of the MP3 and AAC files that were loaded from the selected folder. And the CurrentSongIndex is the position of the current file (in the array) to play.

With this setup out of the way, you can start adding code. The first thing to do is to load the music files from the selected folder. Add the Action event to the “Choose Music Folder” button and enter this code:

' Choose a folder, grab all music files in the folder
' and save in array
Dim musicFolder As FolderItem = SelectFolder
If musicFolder <> Nil Then
  CurrentSongIndex = -1
  ReDim Songs(-1)
 
  Dim count As Integer = musicFolder.Count
  For i As Integer = 1 To count
    Dim f As FolderItem = musicFolder.Item(i)
    If f <> Nil And (f.Name.Right(3) = "mp3" Or f.Name.Right(3) = "m4a") Then
      Songs.Append(f)
    End If
  Next
End If

PlayNextSong

The last line calls a method, PlayNextSong, that starts playing the next song in the array. Here is the code for the PlayNextSong method:

Sub PlayNextSong()
  If CurrentSong <> Nil Then CurrentSong.Stop
 
  CurrentSongIndex = CurrentSongIndex + 1
  If CurrentSongIndex > Songs.Ubound Then CurrentSongIndex = 0
 
  If CurrentSongIndex <= Songs.Ubound Then
    CurrentSong = Songs(CurrentSongIndex).OpenAsSound
    CurrentSong.Play
    NowPlayingLabel.Text = Songs(CurrentSongIndex).Name
  End If
 
End Sub

Note: Do not type the Sub/End Sub part of the method in the code editor; instead enter that information in the Inspector.

This code stops any currently playing song, increases the current song index by 1 (looping back to the start if the end is reached) and then loads the sound file from the array so it can be played. Lastly it updates the label with the name of the song file.

You can do a quick test with just this code in place. Run the project (using the Remote Debugger) on the Pi and choose a folder containing music files. The first song in the folder should start playing.

Adding Features

There are still two buttons on the window that don’t yet do anything. The Play button will be used to Play and Stop the current song. Add the Action event to the Play button and enter this code:

If CurrentSong.IsPlaying Then
  CurrentSong.Stop
Else
  CurrentSong.Play
End If

The Skip button skips to the next song. Add the Action event and have it call the PlayNextSong method:

PlayNextSong

You can now again run the project on the Pi to test out these new features. When music is playing, click the Play button to stop and play. Click the Skip button to skip to and play the next song.

If you’ve let a song play until it finishes, you’ll notice that the next song does not start playing. This is because there is no code to check if the current song has finished. If you recall the code in the Play button it checks a property called “IsPlaying” to see if the song is currently playing. That property could be also be used by a Timer to check if the song has finished playing so it could start playing the next song. However this won’t quite be enough. If the user manually stops the song, then IsPlaying will be false and the Timer will automatically start playing the next song, which is probably not the behavior you want. To track when a user has manually stopped the music, another property is needed. Add this to Window1:

IsSongStopped As Boolean

Now you can drag a Timer on to Window1 and add the Timer’s Action event handler with this code (you can leave the Timer with its default period of 1000 and Mode to Multiple):

If CurrentSong <> Nil Then
  If Not CurrentSong.IsPlaying And Not IsSongStopped Then
    ' The song is no longer playing and the user has not manually stopped
    ' so that must mean the song has finished on its own.
    PlayNextSong
  End If
End If

And lastly, you need to go back to the Play button Action event handler and change its code to set the value in IsSongStopped like this:

If CurrentSong.IsPlaying Then
  CurrentSong.Stop
  IsSongStopped = True
Else
  CurrentSong.Play
  IsSongStopped = False
End If

Run the project on the Pi and you’ll see that the next song starts playing about 1 second after the current song finishes.

More Raspberry Pi Projects

Are you interested in trying more Raspberry Pi projects with Xojo? Download Xojo for free and then check out the free Programming the Raspberry Pi with Xojo book available on the Xojo Dev Center, which contains this project and many others.

These projects are all free and show you how to hook up a variety of sensors to your Pi and then interface with them using Xojo. Topics include:

• Motion Sensor
• Relay Board
• Flame Sensor
• Humidity and Temperature Sensors
• Infrared Sensor
• Ultrasonic Sensor

These projects make use of the open source GPIO module that is included with Xojo and available on GitHub.

You can view all the Pi Projects here:

Xojo Pi/GPIO Projects

You can develop and build console and desktop apps for the Raspberry Pi using Xojo 2019r1 or later for free.

Download Xojo today and get started!

Raspberry Pi is essentially a tiny, inexpensive computer. Because it is tiny, it can be used in all kind of things that a typical computer does not work well with, such as robotics and embedded systems. Since it is also inexpensive, it functions as a great learning tool, making it possible for anyone to have their own computer. Additionally, because a Raspberry Pi is a fully functional computer, with input/output, storage and wifi capabilities, it can also be used to interface and control other things. This makes the Raspberry Pi a favorite amongst tinkerers, Makers, electronics hobbyists and anyone else with a cool idea for a project.

What makes the Raspberry Pi somewhat unique is that it uses an ARM processor (similar to what you see on cell phones and tablets), rather than an Intel CPU that is in most things categorized as “computers”.

Still, a Raspberry Pi is a full computer. You can connect a keyboard, mouse and display to it. You can plug in storage and install an operating system on it (typically Linux). Now, it is not a powerful computer, to be sure, but it is still powerful enough for many tasks.

Although you can program Raspberry Pi, it is not really as easy as it should be. You typically have to deal with scripts, command prompts and other things that make programming less fun. We aim to simplify programming for Raspberry Pi by allowing you to use the simple to learn Xojo IDE and programming language with it.

You can read more about Raspberry Pi, its origins and goals at RaspberryPi.org.

So if you want a Raspberry Pi, how do you get one? There are many places that sell Raspberry Pi and it is available in various configurations and price points. If you want a full kit, that includes everything you need to get started, you can find one at Amazon for about $70 USD. This kit includes the Raspberry Pi itself, a case, power supply, 8GB SD card with OS, USB wifi and cables.

Another common source of Raspberry Pi stuff is Adafruit. There you can buy the bare Raspberry Pi board for $40 or also get lots of other accessories and starter kits.

On the European side of the fence, RobotStore seems to have a lot of Raspberry Pi products.

To learn even more about Raspberry Pi, you might also want to grab MagPi, the free, official magazine of Raspberry Pi. Building for Pi console and desktop is free with a Xojo Pi license in Xojo 2019r1 and beyond!

Or let us walk you through: