xmas_tree/tree.py

   1 # Example code for [charlieplexed] GPIO Xmas Tree for
   2 # Raspberry Pi by Andrew Gale.
   3
   4 import RPi.GPIO as GPIO
   5 import time
   6
   7 # The tree connects to the 6 GPIO pins furthest away from the
   8 # corner of Raspberry Pi i.e. *physical* pin numbers 21-26 on
   9 # the model A or B and 35-40 on the B+.
  10
  11 # Some Kickstarter supporters opted to receive a 'bi-colour'
  12 # LED as their stretch goal reward. This fits in the top
  13 # LED position (i.e. LED_0) but actually contains a second
  14 # LED that we shall call LED_7
  15
  16 # Bicolour LED fitted or not?
  17 # bicolour_fitted = False # the default is False
  18 bicolour_fitted = True # the default is False
  19
  20 # The time for which each LED is illuminated.
  21 # This is the place to tweak the brightness of the bicolour
  22 # LEDs by altering their illumination time.
  23 illumination_time_bicolour_green = 0.004 # the ON time for the bicolour green LED
  24 illumination_time_bicolour_red = 0.004 # the ON time for the bicolour red LED
  25 illumination_time_default = 0.001 # the ON time for all the other LEDs
  26
  27 # The following constants will be configured by tree.setup()
  28 # but we will set them to -1 for now.
  29 A, B, C, D = -1, -1, -1, -1  # The four Charlieplexing nodes
  30 total_illumination_time = -1 # Time for one whole cycle
  31
  32 # The following code to detect which version of Raspberry Pi
  33 # you are using is courtesy of Matt Hawkins at
  34 # http://www.raspberrypi-spy.co.uk
  35
  36 def getrevision():
  37   # Extract board revision from cpuinfo file
  38   myrevision = "0000"
  39   try:
  40     f = open('/proc/cpuinfo','r')
  41     for line in f:
  42       if line[0:8]=='Revision':
  43         length=len(line)
  44         myrevision = line[11:length-1]
  45     f.close()
  46   except:
  47     myrevision = "0000"
  48
  49   return myrevision
  50
  51
  52
  53 def single_led_on(n):
  54   if (A==-1):
  55     print "***********************************************"
  56     print "**                                           **"
  57     print "** ERROR: you MUST call tree.setup() first!! **"
  58     print "**                                           **"
  59     print "***********************************************"
  60     raise Exception('You MUST call tree.setup() first!!')
  61
  62   # First, set all the nodes to be input (effectively
  63   # 'disconnecting' them from the Raspberry Pi)
  64   GPIO.setup(A, GPIO.IN)
  65   GPIO.setup(B, GPIO.IN)
  66   GPIO.setup(C, GPIO.IN)
  67   GPIO.setup(D, GPIO.IN)
  68   GPIO.setup(A2, GPIO.IN)
  69   GPIO.setup(B2, GPIO.IN)
  70   GPIO.setup(C2, GPIO.IN)
  71   GPIO.setup(D2, GPIO.IN)
  72
  73   # Now determine which nodes are connected to the anode
  74   # and cathode for this LED
  75   if   (n==1): anode, cathode = C, A
  76   elif (n==2): anode, cathode = C, D
  77   elif (n==4): anode, cathode = D, C
  78   elif (n==8): anode, cathode = D, B
  79   elif (n==16): anode, cathode = B, D
  80   elif (n==32): anode, cathode = A, B
  81   elif (n==64): anode, cathode = B, A
  82   elif (n==128): anode, cathode = A, C
  83   elif (n==(256+1)): anode, cathode = C2, A2
  84   elif (n==(256+2)): anode, cathode = C2, D2
  85   elif (n==(256+4)): anode, cathode = D2, C2
  86   elif (n==(256+8)): anode, cathode = D2, B2
  87   elif (n==(256+16)): anode, cathode = B2, D2
  88   elif (n==(256+32)): anode, cathode = A2, B2
  89   elif (n==(256+64)): anode, cathode = B2, A2
  90   elif (n==(256+128)): anode, cathode = A2, C2
  91   else: return # invalid LED number
  92
  93   # Configure the anode and cathode nodes to be outputs
  94   GPIO.setup(anode, GPIO.OUT)
  95   GPIO.setup(cathode, GPIO.OUT)
  96
  97   # Make the anode high (+3.3v) and the cathode low (0v)
  98   GPIO.output(anode, GPIO.HIGH)
  99   GPIO.output(cathode, GPIO.LOW)
 100
 101
 102 def leds_on_and_wait(leds, wait_time):
 103   # This routine is passed an 8-bit value (in the "leds"
 104   # parameter) with one bit representing each LED. This routine
 105   # checks each bit in turn and, if it's set to '1' then it
 106   # turns the LED on for 0.001 seconds (or whatever is defined
 107   # in the constants at the top). The whole routine
 108   # loops around as many times as it can in the time specified
 109   # in the "wait_time" parameter, thereby creating the illusion
 110   # that all LEDs are on simultaneously (due to persistence
 111   # of vision) when, in reality, only one is on at a time.
 112
 113   # When used with a bicolour LED at the top of the tree, this
 114   # routine is passed a 9-bit value.
 115   # Bit 7 is for the red LED in the bicolour LED.
 116   # Bit 8 is for the green LED in the bicolour LED.
 117   # Bit 0: to maintain compatibility with code for a non-bicolour version of
 118   # the tree, if bit 0 is set then we want the bicolour LED to light BOTH LEDs
 119   # to mimic the yellow of the non-bicolour version of the tree.
 120
 121   if (bicolour_fitted):
 122     bicolour_leds = 0
 123     if (leds & 1):
 124       # bit 0 is set, so display bicolour as amber/yellow
 125       #leds = (leds & 0b001111110) # preserve the 6 standard red LED bits
 126       bicolour_leds |= (128+1) # enable the red and green bicolour LEDs
 127     if (leds & 128):
 128       # bit 7 is set so display bicolour as red
 129       #leds = (leds & 0b001111110) # preserve the 6 standard red LED bits
 130       bicolour_leds |= 128 # enable the red bicolour LEDs
 131     if (leds & 256):
 132       # bit 8 is set so display bicolour as green
 133       #leds = (leds & 0b001111110) # preserve the 6 standard red LED bits
 134       bicolour_leds |= 1 # enable the green bicolour LEDs
 135     if (leds & 2**9):
 136       # bit 9 is set, so display second bicolour as amber/yellow
 137       #leds = (leds & 0b001111110) # preserve the 6 standard red LED bits
 138       bicolour_leds |= (2**15+2**8) # enable the red and green bicolour LEDs
 139     if (leds & 2**16):
 140       # bit 16 is set so display bicolour as red
 141       #leds = (leds & 0b001111110) # preserve the 6 standard red LED bits
 142       bicolour_leds |= 2**15 # enable the red bicolour LEDs
 143     if (leds & 2*17):
 144       # bit 8 is set so display bicolour as green
 145       #leds = (leds & 0b001111110) # preserve the 6 standard red LED bits
 146       bicolour_leds |= 2**8 # enable the green bicolour LEDs
 147     leds = (leds & 0b00111111001111110) # preserve the 6 standard red LED bits
 148     leds = leds | bicolour_leds
 149   print '{:017b}'.format(leds)
 150
 151   for j in range(int(wait_time/total_illumination_time)):
 152     for i in range(16):
 153       single_led_on(leds & (1<<i))
 154
 155       if (bicolour_fitted and (i==0 or i == 8)):
 156         time.sleep(illumination_time_bicolour_green)
 157       elif (bicolour_fitted and (i==7 or i == 16)):
 158         time.sleep(illumination_time_bicolour_red)
 159       else:
 160         time.sleep(illumination_time_default)
 161
 162
 163 def all_leds_off():
 164   single_led_on(0)
 165
 166 def setup():
 167   global A
 168   global B
 169   global C
 170   global D
 171   global A2
 172   global B2
 173   global C2
 174   global D2
 175   global total_illumination_time
 176
 177   GPIO.setmode(GPIO.BCM)
 178
 179   # choose the correct GPIO pins depending on model
 180   revision = getrevision()
 181   print "** revision: ", revision
 182   if ((revision == "0010") or (revision == "0012")):
 183     print "Model B+ or A+"
 184     A, B, C, D = 21, 19, 26, 20
 185   else:
 186     print "Other model, probably Model A or Model B"
 187     print "Pi 2"
 188     # A, B, C, D = 7, 9, 11, 8
 189     A, B, C, D = 15, 3, 4, 14 # near corner
 190     A2, B2, C2, D2 = 21, 19, 26, 20 # near USB
 191
 192
 193   if (bicolour_fitted):
 194     total_illumination_time = 6 * illumination_time_default
 195     total_illumination_time += illumination_time_bicolour_green
 196     total_illumination_time += illumination_time_bicolour_red
 197   else:
 198     total_illumination_time = 8 * illumination_time_default
 199
 200   #print "total_illumination_time: ", total_illumination_time
 201
 202 def cleanup():
 203   GPIO.cleanup()
 204