src/adafruit_blinka/microcontroller/raspi_23/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      = ws.WS2811_STRIP_RGB # 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         ws.ws2811_channel_t_count_set(channel, math.ceil(len(buf)/3)) # we manage 4 vs 3 bytes in the library
  40         ws.ws2811_channel_t_gpionum_set(channel, gpio._pin.id)
  41         ws.ws2811_channel_t_invert_set(channel, LED_INVERT)
  42         ws.ws2811_channel_t_brightness_set(channel, LED_BRIGHTNESS)
  43         ws.ws2811_channel_t_strip_type_set(channel, LED_STRIP)
  44
  45         # Initialize the controller
  46         ws.ws2811_t_freq_set(_led_strip, LED_FREQ_HZ)
  47         ws.ws2811_t_dmanum_set(_led_strip, LED_DMA_NUM)
  48
  49         resp = ws.ws2811_init(_led_strip)
  50         if resp != ws.WS2811_SUCCESS:
  51             message = ws.ws2811_get_return_t_str(resp)
  52             raise RuntimeError('ws2811_init failed with code {0} ({1})'.format(resp, message))
  53         atexit.register(neopixel_cleanup)
  54
  55     channel = ws.ws2811_channel_get(_led_strip, LED_CHANNEL)
  56     if gpio._pin.id != ws.ws2811_channel_t_gpionum_get(channel):
  57         raise RuntimeError("Raspberry Pi neopixel support is for one strip only!")
  58
  59     # assign all colors!
  60     for i in range(len(buf) // 3):
  61         r = buf[3*i]
  62         g = buf[3*i+1]
  63         b = buf[3*i+2]
  64         pixel = (r << 16) | (g << 8) | b
  65         ws.ws2811_led_set(channel, i, pixel)
  66
  67     resp = ws.ws2811_render(_led_strip)
  68     if resp != ws.WS2811_SUCCESS:
  69         message = ws.ws2811_get_return_t_str(resp)
  70         raise RuntimeError('ws2811_render failed with code {0} ({1})'.format(resp, message))
  71     time.sleep(0.001 * ((len(buf)//100)+1))  # about 1ms per 100 bytes
  72
  73
  74 def neopixel_cleanup():
  75     global _led_strip
  76
  77     if _led_strip is not None:
  78         # Ensure ws2811_fini is called before the program quits.
  79         ws.ws2811_fini(_led_strip)
  80         # Example of calling delete function to clean up structure memory.  Isn't
  81         # strictly necessary at the end of the program execution here, but is good practice.
  82         ws.delete_ws2811_t(_led_strip)
  83         _led_strip = None