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neopixel.py
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neopixel.py
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# SPDX-FileCopyrightText: 2021 Melissa LeBlanc-Williams for Adafruit Industries
#
# SPDX-License-Identifier: MIT
"""BCM283x NeoPixel Driver Class"""
import time
import atexit
import _rpi_ws281x as ws
# LED configuration.
# pylint: disable=redefined-outer-name,too-many-branches,too-many-statements
# pylint: disable=global-statement,protected-access
LED_CHANNEL = 0
LED_FREQ_HZ = 800000 # Frequency of the LED signal. We only support 800KHz
LED_DMA_NUM = 10 # DMA channel to use, can be 0-14.
LED_BRIGHTNESS = 255 # We manage the brightness in the neopixel library
LED_INVERT = 0 # We don't support inverted logic
LED_STRIP = None # We manage the color order within the neopixel library
# a 'static' object that we will use to manage our PWM DMA channel
# we only support one LED strip per raspi
_led_strip = None
_buf = None
def neopixel_write(gpio, buf):
"""NeoPixel Writing Function"""
global _led_strip # we'll have one strip we init if its not at first
global _buf # we save a reference to the buf, and if it changes we will cleanup and re-init.
if _led_strip is None or buf is not _buf:
# This is safe to call since it doesn't do anything if _led_strip is None
neopixel_cleanup()
# Create a ws2811_t structure from the LED configuration.
# Note that this structure will be created on the heap so you
# need to be careful that you delete its memory by calling
# delete_ws2811_t when it's not needed.
_led_strip = ws.new_ws2811_t()
_buf = buf
# Initialize all channels to off
for channum in range(2):
channel = ws.ws2811_channel_get(_led_strip, channum)
ws.ws2811_channel_t_count_set(channel, 0)
ws.ws2811_channel_t_gpionum_set(channel, 0)
ws.ws2811_channel_t_invert_set(channel, 0)
ws.ws2811_channel_t_brightness_set(channel, 0)
channel = ws.ws2811_channel_get(_led_strip, LED_CHANNEL)
# Initialize the channel in use
count = 0
if len(buf) % 3 == 0:
# most common, divisible by 3 is likely RGB
LED_STRIP = ws.WS2811_STRIP_RGB
count = len(buf) // 3
elif len(buf) % 4 == 0:
LED_STRIP = ws.SK6812_STRIP_RGBW
count = len(buf) // 4
else:
raise RuntimeError("We only support 3 or 4 bytes-per-pixel")
ws.ws2811_channel_t_count_set(
channel, count
) # we manage 4 vs 3 bytes in the library
ws.ws2811_channel_t_gpionum_set(channel, gpio._pin.id)
ws.ws2811_channel_t_invert_set(channel, LED_INVERT)
ws.ws2811_channel_t_brightness_set(channel, LED_BRIGHTNESS)
ws.ws2811_channel_t_strip_type_set(channel, LED_STRIP)
# Initialize the controller
ws.ws2811_t_freq_set(_led_strip, LED_FREQ_HZ)
ws.ws2811_t_dmanum_set(_led_strip, LED_DMA_NUM)
resp = ws.ws2811_init(_led_strip)
if resp != ws.WS2811_SUCCESS:
if resp == -5:
raise RuntimeError(
"NeoPixel support requires running with sudo, please try again!"
)
message = ws.ws2811_get_return_t_str(resp)
raise RuntimeError(
"ws2811_init failed with code {0} ({1})".format(resp, message)
)
atexit.register(neopixel_cleanup)
channel = ws.ws2811_channel_get(_led_strip, LED_CHANNEL)
if gpio._pin.id != ws.ws2811_channel_t_gpionum_get(channel):
raise RuntimeError("Raspberry Pi neopixel support is for one strip only!")
if ws.ws2811_channel_t_strip_type_get(channel) == ws.WS2811_STRIP_RGB:
bpp = 3
else:
bpp = 4
# assign all colors!
for i in range(len(buf) // bpp):
r = buf[bpp * i]
g = buf[bpp * i + 1]
b = buf[bpp * i + 2]
if bpp == 3:
pixel = (r << 16) | (g << 8) | b
else:
w = buf[bpp * i + 3]
pixel = (w << 24) | (r << 16) | (g << 8) | b
ws.ws2811_led_set(channel, i, pixel)
resp = ws.ws2811_render(_led_strip)
if resp != ws.WS2811_SUCCESS:
message = ws.ws2811_get_return_t_str(resp)
raise RuntimeError(
"ws2811_render failed with code {0} ({1})".format(resp, message)
)
time.sleep(0.001 * ((len(buf) // 100) + 1)) # about 1ms per 100 bytes
def neopixel_cleanup():
"""Cleanup when we're done"""
global _led_strip
if _led_strip is not None:
# Ensure ws2811_fini is called before the program quits.
ws.ws2811_fini(_led_strip)
# Example of calling delete function to clean up structure memory. Isn't
# strictly necessary at the end of the program execution here, but is good practice.
ws.delete_ws2811_t(_led_strip)
_led_strip = None