src/adafruit_blinka/microcontroller/bcm283x/neopixel.py

   1 import time
   2 import math
   3 import _rpi_ws281x as ws
   4 import atexit
   5
   6 # LED configuration.
   7 LED_CHANNEL    = 0
   8 LED_FREQ_HZ    = 800000     # Frequency of the LED signal.  We only support 800KHz
   9 LED_DMA_NUM    = 10         # DMA channel to use, can be 0-14.
  10 LED_BRIGHTNESS = 255        # We manage the brightness in the neopixel library
  11 LED_INVERT     = 0          # We don't support inverted logic
  12 LED_STRIP      = None # We manage the color order within the neopixel library
  13
  14 # a 'static' object that we will use to manage our PWM DMA channel
  15 # we only support one LED strip per raspi
  16 _led_strip = None
  17
  18 def neopixel_write(gpio, buf):
  19     global _led_strip # we'll have one strip we init if its not at first
  20
  21     if _led_strip is None:
  22         # Create a ws2811_t structure from the LED configuration.
  23         # Note that this structure will be created on the heap so you
  24         # need to be careful that you delete its memory by calling
  25         # delete_ws2811_t when it's not needed.
  26         _led_strip = ws.new_ws2811_t()
  27
  28         # Initialize all channels to off
  29         for channum in range(2):
  30             channel = ws.ws2811_channel_get(_led_strip, channum)
  31             ws.ws2811_channel_t_count_set(channel, 0)
  32             ws.ws2811_channel_t_gpionum_set(channel, 0)
  33             ws.ws2811_channel_t_invert_set(channel, 0)
  34             ws.ws2811_channel_t_brightness_set(channel, 0)
  35
  36         channel = ws.ws2811_channel_get(_led_strip, LED_CHANNEL)
  37
  38         # Initialize the channel in use
  39         count = 0
  40         if len(buf) % 3 == 0:
  41             # most common, divisible by 3 is likely RGB
  42             LED_STRIP = ws.WS2811_STRIP_RGB
  43             count = len(buf)//3
  44         elif len(buf) % 4 == 0:
  45             LED_STRIP = ws.SK6812_STRIP_RGBW
  46             count = len(buf)//4
  47         else:
  48             raise RuntimeError("We only support 3 or 4 bytes-per-pixel")
  49
  50         ws.ws2811_channel_t_count_set(channel, count) # we manage 4 vs 3 bytes in the library
  51         ws.ws2811_channel_t_gpionum_set(channel, gpio._pin.id)
  52         ws.ws2811_channel_t_invert_set(channel, LED_INVERT)
  53         ws.ws2811_channel_t_brightness_set(channel, LED_BRIGHTNESS)
  54         ws.ws2811_channel_t_strip_type_set(channel, LED_STRIP)
  55
  56         # Initialize the controller
  57         ws.ws2811_t_freq_set(_led_strip, LED_FREQ_HZ)
  58         ws.ws2811_t_dmanum_set(_led_strip, LED_DMA_NUM)
  59
  60         resp = ws.ws2811_init(_led_strip)
  61         if resp != ws.WS2811_SUCCESS:
  62             if resp == -5:
  63                 raise RuntimeError("NeoPixel support requires running with sudo, please try again!")
  64             message = ws.ws2811_get_return_t_str(resp)
  65             raise RuntimeError('ws2811_init failed with code {0} ({1})'.format(resp, message))
  66         atexit.register(neopixel_cleanup)
  67
  68     channel = ws.ws2811_channel_get(_led_strip, LED_CHANNEL)
  69     if gpio._pin.id != ws.ws2811_channel_t_gpionum_get(channel):
  70         raise RuntimeError("Raspberry Pi neopixel support is for one strip only!")
  71
  72     if ws.ws2811_channel_t_strip_type_get(channel) == ws.WS2811_STRIP_RGB:
  73         bpp = 3
  74     else:
  75         bpp = 4
  76     # assign all colors!
  77     for i in range(len(buf) // bpp):
  78         r = buf[bpp*i]
  79         g = buf[bpp*i+1]
  80         b = buf[bpp*i+2]
  81         if bpp == 3:
  82             pixel = (r << 16) | (g << 8) | b
  83         else:
  84             w = buf[bpp*i+3]
  85             pixel = (w << 24) | (r << 16) | (g << 8) | b
  86         ws.ws2811_led_set(channel, i, pixel)
  87
  88     resp = ws.ws2811_render(_led_strip)
  89     if resp != ws.WS2811_SUCCESS:
  90         message = ws.ws2811_get_return_t_str(resp)
  91         raise RuntimeError('ws2811_render failed with code {0} ({1})'.format(resp, message))
  92     time.sleep(0.001 * ((len(buf)//100)+1))  # about 1ms per 100 bytes
  93
  94
  95 def neopixel_cleanup():
  96     global _led_strip
  97
  98     if _led_strip is not None:
  99         # Ensure ws2811_fini is called before the program quits.
 100         ws.ws2811_fini(_led_strip)
 101         # Example of calling delete function to clean up structure memory.  Isn't
 102         # strictly necessary at the end of the program execution here, but is good practice.
 103         ws.delete_ws2811_t(_led_strip)
 104         _led_strip = None