树莓派4B-Python-控制WS2812

客官°小女子只卖身不卖艺 2022-11-30 01:44 511阅读 0赞

本篇文章是使用树莓派4B点亮WS2812灯环，并实现多种颜色的变换。

### 树莓派4B-Python-控制WS2812B ###

*  WS2812
 *  参数介绍与工作原理
 *  与树莓派4B连接
 *  代码
 *   *  可能会出现的问题：

之前心血来潮，在本人那小电风扇上装了一个可控LED灯WS2812，只为了拥有更好的夜晚灯光视觉效果（好吧我承认是有点无聊）。

![风扇][20200825091137174.jpg_pic_center]

![WS812][]

# WS2812 #

> WS2812B是一个集控制电路与发光电路于一体的智能外控LED光源，其外型与一个5050LED灯珠相同，每个元件即为一个像素点。

![ws2812][]

# 参数介绍与工作原理 #

这里本人就不重复说明了，详情请参考以下博客/论坛等，希望对你有所帮助。  
[参考1][1]

[参考2][2]

[参考3][3]

[参考4][4]

# 与树莓派4B连接 #

![WS2812连接树莓派][WS2812]  
红色------5V  
蓝色------GND  
黄色------GPIO18

# 代码 #

首先需要安装相关库：

sudo pip install rpi-ws281x

**若没有安装pip的还得先安装pip：（装了则跳过此步骤）**

sudo apt-get install python-pip

以下为灯光多种变换的代码，一个函数一种变换：

import time
    from rpi_ws281x import PixelStrip, Color
    import argparse
    
    LED_COUNT = 16        # LED灯的个数
    LED_PIN = 18          # DI端接GPIO18
    
    # 以下可以不用改
    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
    
    # 以下为LED模式变换的各个函数
    def colorWipe(strip, color, wait_ms=20):
        """一次擦除显示像素的颜色."""
        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):
        """电影影院灯光风格的追逐动画."""
        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):
        """生成横跨0-255个位置的彩虹颜色."""
        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):
        """绘制彩虹，褪色的所有像素一次."""
        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=10, iterations=5):
        """画出均匀分布在所有像素上的彩虹."""
        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):
        """旋转的彩色灯光."""
        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, 255, 0))  # Red wipe
                colorWipe(strip, Color(0, 0, 0), 30)
                colorWipe(strip, Color(0, 255, 255))  # Blue wipe
                colorWipe(strip, Color(0, 0, 0), 30)
                colorWipe(strip, Color(255, 0, 255))  # Green wipe
                colorWipe(strip, Color(0, 0, 0), 30)
                
                print('Theater chase animations.')
                print('Rainbow animations.')
                rainbow(strip)
                colorWipe(strip, Color(0, 0, 0), 50)
                rainbowCycle(strip)
                colorWipe(strip, Color(0, 0, 0), 40)
                break
            while True:
                rainbowCycle(strip)
                #print('***********************')
                colorWipe(strip, Color(0, 0, 0), 100)
    
        except:
            colorWipe(strip, Color(0, 0, 0), 100)

## 可能会出现的问题： ##

问题1：提示 “strip.begin()” 该代码出错，显示错误为：

RuntimeError: ws2811_init failed with code -5 (mmap() failed)

原因：直接从IDE上运行了该程序。  
解决方法：从命令行上运行程序。方法如下：  
①假设程序文件放在桌面上

cd Desktop

②进入桌面后打开程序文件，假设文件名为123.py

sudo python3 123.py

③运行时若想要退出就按Ctrl + C  
问题2：  
不能使用中文注释？

**经过验证，其实是可以的使用中文注释的，并且根本不用删除注释再运行程序，完全不受影响**

问题3：  
出现ImportError: No module named \_rpi\_ws281x的错误提示

较大的可能是安装错了，用pip安装可能是Python2的，用pip3安装就能解决

sudo pip3 install rpi-ws281x

\#\#2020.8.29

[20200825091137174.jpg_pic_center]: /images/20221124/32954ca829a24fcebfc1a18cdf095bc9.png
[WS812]: /images/20221124/1e35dcc8560a46fdad03951365faec77.png
[ws2812]: /images/20221124/c46ac9a286ab447fa7b35eabeaf8842b.png
[1]: https://blog.csdn.net/tangxing1212/article/details/42964417?utm_medium=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-3.nonecase&depth_1-utm_source=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-3.nonecase
[2]: http://www.51hei.com/bbs/forum.php?mod=viewthread&tid=170712&from=album
[3]: https://www.dellts.cn/article/88.html
[4]: https://zhuanlan.zhihu.com/p/146410294
[WS2812]: /images/20221124/f679a8eb623e4c1ba2fd4033df5d3990.png