There are thousands of free radio stations on the internet, and with this project you can listen to all of them from one tiny little box. So let’s build our streaming radio using a Raspberry Pi, a speaker and a few odds and ends…
What you’ll need
A wireless internet connection
2 x momentary switches
4 x female-to-male leads (to connect your Pi to a breadboard)
2 x 220-ohm resistors
4 x male-to-male leads
Speakers connected to 3.5mm headphone jack
Step 01 Let’s get set up
Firstly, we need to prepare our Pi. Using Raspbian, and a Pi connected to the internet, open a terminal and switch to the root user:
And update your list of packages, then upgrade your Pi to the latest software:
apt-get update && apt-get upgrade -y
Step 02 Install some extra packages
We need to install the Python packages to access the GPIO. In a terminal, logged in as root, enter the following.
apt-get install python-rpi.gpio
Now install MPlayer, which is what will be playing our audio.
apt-get install mplayer
Step 03 Set up your hardware
We will be using GPIO 23 and 24 to provide connections for two push buttons.
You will need 4 female to male leads to connect GPIO 23,24,3v3 and GND to the breadboard. You will also need 4 male to male leads, and 2, 220 ohm resistors. Please refer to the diagram for wiring guidelines.
Step 04 Setup the software
Copy the code listing into a file called radio.py and put that in your home directory – we’ll use the code as is for this guide, but feel free to edit the code to suit your needs later on.
Now open a terminal and switch to root, and edit your network interface config:
Step 05 Wi-Fi configuration
We want the Pi to automatically connect to your router via Wi-Fi during boot.
Edit your /etc/network/interfaces file to resemble this:
auto lo iface lo inet loopback iface eth0 inet dhcp allow-hotplug wlan0 auto wlan0 iface wlan0 inet dhcp wpa-ssid “ssid” wpa-psk “password”
Replace the “ssid” and “password” with your own details, but keep the quotation marks.
Step 06 Configure the radio to start at boot
In a terminal, as root, navigate to /etc/init.d/ and then create a file called radio
In that file, type in the following:
#! /bin/bash modprobe snd_bcm2835 amixer cset numid=3 1 python /home/pi/radio.py
This loads the kernel module for the sound card Amixer sets the output to the 3.5mm headphone jack (that’s what 1 means, HDMI is 2). Lastly it calls the Python script.
Step 07 Make it executable
Save and exit radio in /etc/init.d by pressing Ctrl+X and then answering yes to the prompt.
Now make radio executable by typing (as root):
chmod 755 radio
Then, as root, register radio to start on boot by typing in a terminal:
update-rc.d radio defaults
Step 08 Raspi-config
In a terminal as root, use raspi-config to change the boot behaviour of your Pi. We don’t want it to load the desktop – a terminal is all we need, as the project will not require a screen for future use…
Once complete, reboot the Pi and watch as the output from boot whizzes across the screen.
Once the Pi has finished loading, press one of the buttons on your breadboard. In a few seconds you should hear the audio come through the speakers that you attached to the 3.5mm headphone jack.
#!/usr/bin env python import time import sleep import os import RPi.GPIO as GPIO # I found loads of BBC Radio streams from http://bbcstreams.com/ GPIO.setmode(GPIO.BCM) GPIO.setup(23 , GPIO.IN) GPIO.setup(24 , GPIO.IN) while True: if GPIO.input(23)==1: os.system(‘sudo killall mplayer’) os.system(‘mplayer -playlist http://bbc.co.uk/radio/listen/live/r1.asx &’) if GPIO.input(24)==1: os.system(‘sudo killall mplayer’) os.system(‘mplayer -playlist http://bbc.co.uk/radio/listen/live/r6.asx &’) sleep(0.1); GPIO.cleanup()
This tutorial appears in the magazine and the Raspberry Pi The Complete Manual.