[嵌入式]树莓派驱动 WS2812 灯珠 不亮的问题

前言

树莓派在控制某些硬件外设上坑还真不少，今天就又踩了一个（其实有两天了）。其实越复杂的问题往往是有越简单的解决办法。
树莓派驱动ws2812 网上一搜几乎都是 用的 rpi-ws281x 这个库

安装

安装还是比较简单

sudo pip3 install rpi-ws281x

官方示例

看看官方的示例程序 ,这是一个名为 strandtest.py 的示例程序
当然还有其他的示例程序 Github链接

#!/usr/bin/env python3
# NeoPixel library strandtest example
# Author: Tony DiCola (tony@tonydicola.com)
#
# Direct port of the Arduino NeoPixel library strandtest example.  Showcases
# various animations on a strip of NeoPixels.

import time
from rpi_ws281x import PixelStrip, Color
import argparse

# LED strip configuration:
LED_COUNT = 16        # Number of LED pixels.
LED_PIN = 18          # GPIO pin connected to the pixels (18 uses PWM!).
# LED_PIN = 10        # GPIO pin connected to the pixels (10 uses SPI /dev/spidev0.0).
LED_FREQ_HZ = 800000  # LED signal frequency in hertz (usually 800khz)
LED_DMA = 10          # DMA channel to use for generating signal (try 10)
LED_BRIGHTNESS = 255  # Set to 0 for darkest and 255 for brightest
LED_INVERT = False    # True to invert the signal (when using NPN transistor level shift)
LED_CHANNEL = 0       # set to '1' for GPIOs 13, 19, 41, 45 or 53


# Define functions which animate LEDs in various ways.
def colorWipe(strip, color, wait_ms=50):
    """Wipe color across display a pixel at a time."""
    for i in range(strip.numPixels()):
        strip.setPixelColor(i, color)
        strip.show()
        time.sleep(wait_ms / 1000.0)


def theaterChase(strip, color, wait_ms=50, iterations=10):
    """Movie theater light style chaser animation."""
    for j in range(iterations):
        for q in range(3):
            for i in range(0, strip.numPixels(), 3):
                strip.setPixelColor(i + q, color)
            strip.show()
            time.sleep(wait_ms / 1000.0)
            for i in range(0, strip.numPixels(), 3):
                strip.setPixelColor(i + q, 0)


def wheel(pos):
    """Generate rainbow colors across 0-255 positions."""
    if pos < 85:
        return Color(pos * 3, 255 - pos * 3, 0)
    elif pos < 170:
        pos -= 85
        return Color(255 - pos * 3, 0, pos * 3)
    else:
        pos -= 170
        return Color(0, pos * 3, 255 - pos * 3)


def rainbow(strip, wait_ms=20, iterations=1):
    """Draw rainbow that fades across all pixels at once."""
    for j in range(256 * iterations):
        for i in range(strip.numPixels()):
            strip.setPixelColor(i, wheel((i + j) & 255))
        strip.show()
        time.sleep(wait_ms / 1000.0)


def rainbowCycle(strip, wait_ms=20, iterations=5):
    """Draw rainbow that uniformly distributes itself across all pixels."""
    for j in range(256 * iterations):
        for i in range(strip.numPixels()):
            strip.setPixelColor(i, wheel(
                (int(i * 256 / strip.numPixels()) + j) & 255))
        strip.show()
        time.sleep(wait_ms / 1000.0)


def theaterChaseRainbow(strip, wait_ms=50):
    """Rainbow movie theater light style chaser animation."""
    for j in range(256):
        for q in range(3):
            for i in range(0, strip.numPixels(), 3):
                strip.setPixelColor(i + q, wheel((i + j) % 255))
            strip.show()
            time.sleep(wait_ms / 1000.0)
            for i in range(0, strip.numPixels(), 3):
                strip.setPixelColor(i + q, 0)


# Main program logic follows:
if __name__ == '__main__':
    # Process arguments
    parser = argparse.ArgumentParser()
    parser.add_argument('-c', '--clear', action='store_true', help='clear the display on exit')
    args = parser.parse_args()

    # Create NeoPixel object with appropriate configuration.
    strip = PixelStrip(LED_COUNT, LED_PIN, LED_FREQ_HZ, LED_DMA, LED_INVERT, LED_BRIGHTNESS, LED_CHANNEL)
    # Intialize the library (must be called once before other functions).
    strip.begin()

    print('Press Ctrl-C to quit.')
    if not args.clear:
        print('Use "-c" argument to clear LEDs on exit')

    try:

        while True:
            print('Color wipe animations.')
            colorWipe(strip, Color(255, 0, 0))  # Red wipe
            colorWipe(strip, Color(0, 255, 0))  # Green wipe
            colorWipe(strip, Color(0, 0, 255))  # Blue wipe
            print('Theater chase animations.')
            theaterChase(strip, Color(127, 127, 127))  # White theater chase
            theaterChase(strip, Color(127, 0, 0))  # Red theater chase
            theaterChase(strip, Color(0, 0, 127))  # Blue theater chase
            print('Rainbow animations.')
            rainbow(strip)
            rainbowCycle(strip)
            theaterChaseRainbow(strip)

    except KeyboardInterrupt:
        if args.clear:
            colorWipe(strip, Color(0, 0, 0), 10)

测试

新建一个py文件，copy上面那个示例程序，使用命令行运行 (直接在IDE运行会报错，目前不知道解决办法)
比如 我建的名字为 test.py, 放在了桌面

cd Desktop
sudo python3 test.py

虽然没报错，但是灯是没有任何反应的，经过一番查找，在这里找到了原因，原来需要关闭音频输出。。。。。。

打开终端运行

sudo nano /etc/modprobe.d/snd-blacklist.conf

添加下列语句

blacklist snd_bcm2835

ctrl+o保存 ctrl+x退出

修改conf.txt文件

sudo nano /boot/config.txt

找到下列语句(一般是在最下面)

# Enable audio (loads snd_bcm2835)
dtparam=audio=on

注释掉第二行

# Enable audio (loads snd_bcm2835)
#dtparam=audio=on

ctrl+o保存 ctrl+x退出

重启

sudo reboot

再次运行程序，可以成功点亮