Internet Radio Player with Raspberry Pi, PiFace CAD and MPD/MPC

radio.py

import pifacecad
import os
import sys
import subprocess
from time import sleep

backlight = 0
status = "stopped"
channel_pos = 0
channelLink = ["mms://streaming.q-music.be/QBE_HI", "http://mp3.streampower.be/stubru-high.mp3"]
channelName = ["Q-Music BE", "Studio Brussel"]

# Update display and perform action depending on button pressed
def update_pin_text(event):
	global channel_pos
	global status
	
	if(event.pin_num == 0):
		status = "playing"
		os.system('mpc play')
		event.chip.lcd.set_cursor(0, 1)
		event.chip.lcd.write_custom_bitmap(1)
		event.chip.lcd.write(" ")
		display_channel()
		display_playlist()
	
	elif(event.pin_num == 1):
		status = "stopped"
		os.system('mpc stop')
		event.chip.lcd.set_cursor(0, 1)
		event.chip.lcd.write_custom_bitmap(2)
		event.chip.lcd.write(" ")
		clear_channel()
		
	elif(event.pin_num == 2 and status == "playing" and channel_pos > 1):
		os.system('mpc prev')
		clear_channel()
		display_channel()
		display_playlist()
		
	elif(event.pin_num == 3 and status == "playing" and channel_pos < len(channelLink)):
		os.system('mpc next')
		clear_channel()
		display_channel()
		display_playlist()
		
	elif(event.pin_num == 4):
		global backlight
		if(backlight == 1):
			event.chip.lcd.backlight_off()
			backlight = 0
		else:
			event.chip.lcd.backlight_on()
			backlight = 1
			
	elif(event.pin_num == 5):
		sleep(1)
		
	elif(event.pin_num == 6):
		os.system('mpc volume -5')
		display_volume()
		
	elif(event.pin_num == 7):
		os.system('mpc volume \+5')
		display_volume()
	
	else:
		sleep(1)

# Create the playlist with configurable internet radio channels
def create_playlist():
	subprocess.check_output("mpc clear", shell=True, stderr=subprocess.STDOUT, universal_newlines=True)
	
	for channel in channelLink:
		subprocess.check_output("mpc add " + channel, shell=True, stderr=subprocess.STDOUT, universal_newlines=True)

# Define and store custom bitmaps to be displayed
def custom_bitmaps():
	speaker = pifacecad.LCDBitmap([1,3,15,15,15,3,1,0])
	play = pifacecad.LCDBitmap([0,8,12,14,12,8,0,0])
	stop = pifacecad.LCDBitmap([0,31,31,31,31,31,0,0])
	playlist = pifacecad.LCDBitmap([2,3,2,2,14,30,12,0])
	
	cad.lcd.store_custom_bitmap(0, speaker)
	cad.lcd.store_custom_bitmap(1, play)
	cad.lcd.store_custom_bitmap(2, stop)
	cad.lcd.store_custom_bitmap(3, playlist)

# Init display by showing idle state    
def init_display():
	cad.lcd.blink_off()
	cad.lcd.cursor_off()
	cad.lcd.clear()
	cad.lcd.set_cursor(11, 1)
	cad.lcd.write_custom_bitmap(0)
	display_volume()

# Retrieve and display channel name based on playlist position    
def display_channel():
	global channel_pos
	channel = subprocess.check_output("mpc status | grep playing", shell=True, stderr=subprocess.STDOUT, universal_newlines=True)
	channel = channel[channel.find("#")+1:channel.find("/")]
	channel_pos = int(channel)
	channel = channelName[int(channel)-1]
	
	cad.lcd.set_cursor(0, 0)
	cad.lcd.write(channel)

# Write an empty row
def clear_channel():
	cad.lcd.set_cursor(0, 0)
	cad.lcd.write("                ")

# Retrieve plylist position and size from mpc and display
def display_playlist():
	playlist = subprocess.check_output("mpc status | grep playing", shell=True, stderr=subprocess.STDOUT, universal_newlines=True)
	playlist = playlist[playlist.find("#")+1:playlist.find("/")+2]
	
	cad.lcd.set_cursor(4, 1)
	cad.lcd.write_custom_bitmap(3)
	cad.lcd.write(playlist)

# Retrieve volume level from mpc and display
def display_volume():
	volume = subprocess.check_output("mpc status | grep volume", shell=True, stderr=subprocess.STDOUT, universal_newlines=True)
	volume = volume[7:volume.find("%")+1]
	
	cad.lcd.set_cursor(12, 1)
	cad.lcd.write(volume)
    
cad = pifacecad.PiFaceCAD()

custom_bitmaps()
create_playlist()
init_display()

listener = pifacecad.SwitchEventListener(chip=cad)

for i in range(8):
	listener.register(i, pifacecad.IODIR_FALLING_EDGE, update_pin_text)
	
listener.activate()