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neopixel_write: add support for PWM1 pins on Raspberry Pis #931

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neopixel_write: add support for PWM1 pins on Raspberry Pis #931

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23 changes: 18 additions & 5 deletions src/adafruit_blinka/microcontroller/bcm283x/neopixel.py
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Original file line number Diff line number Diff line change
Expand Up @@ -6,10 +6,16 @@
import atexit
import _rpi_ws281x as ws

try:
# Used only for typing
from typing import Optional
from digitalio import DigitalInOut
except ImportError:
pass

# 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
Expand All @@ -19,10 +25,10 @@
# 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
_buf: Optional[bytearray] = None


def neopixel_write(gpio, buf):
def neopixel_write(gpio: DigitalInOut, buf: bytearray) -> None:
"""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.
Expand All @@ -46,7 +52,7 @@ def neopixel_write(gpio, buf):
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)
channel = ws.ws2811_channel_get(_led_strip, _neopixel_detect_channel(gpio))

# Initialize the channel in use
count = 0
Expand Down Expand Up @@ -84,7 +90,7 @@ def neopixel_write(gpio, buf):
)
atexit.register(neopixel_cleanup)

channel = ws.ws2811_channel_get(_led_strip, LED_CHANNEL)
channel = ws.ws2811_channel_get(_led_strip, _neopixel_detect_channel(gpio))
if gpio._pin.id != ws.ws2811_channel_t_gpionum_get(channel):
raise RuntimeError("Raspberry Pi neopixel support is for one strip only!")

Expand Down Expand Up @@ -124,3 +130,10 @@ def neopixel_cleanup():
# strictly necessary at the end of the program execution here, but is good practice.
ws.delete_ws2811_t(_led_strip)
_led_strip = None


def _neopixel_detect_channel(gpio: DigitalInOut) -> int:
"""Detect the channel for a given GPIO, added for support PWM1 pins"""
if gpio._pin.id in (13, 19, 41, 45):
return 1
return 0
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