### 使用Python实现三色LED流水灯效果 #### 实现环境准备 为了能够运行这些例子，需要确保安装了RPi.GPIO库用于控制树莓派上的GPIO引脚。可以通过pip来安装这个库[^1]。 ```bash pip install RPi.GPIO ``` #### 流水灯模式一：单向流动 在这个模式下，红绿蓝三种颜色依次点亮并熄灭形成一种向前推进的效果。 ```python import time import RPi.GPIO as GPIO pins = {'Red': 17, 'Green': 27, 'Blue': 22} def setup(): global p_R, p_G, p_B GPIO.setmode(GPIO.BCM) for pin in pins.values(): GPIO.setup(pin, GPIO.OUT) setup() try: while True: for color, pin in pins.items(): GPIO.output(pin, GPIO.HIGH) time.sleep(0.5) # 延迟一段时间让灯光持续亮起 GPIO.output(pin, GPIO.LOW) except KeyboardInterrupt: pass finally: GPIO.cleanup() ``` #### 流水灯模式二：双向交替闪烁 此模式中红色和绿色先一起亮再同时关闭；接着蓝色单独亮一次之后再次回到红色加绿色的状态循环往复。 ```python while True: GPIO.output(pins['Red'], GPIO.HIGH) GPIO.output(pins['Green'], GPIO.HIGH) time.sleep(0.5) GPIO.output(pins['Red'], GPIO.LOW) GPIO.output(pins['Green'], GPIO.LOW) time.sleep(0.5) GPIO.output(pins['Blue'], GPIO.HIGH) time.sleep(1) GPIO.output(pins['Blue'], GPIO.LOW) time.sleep(0.5) ``` #### 流水灯模式三：渐变过渡 通过调整PWM占空比可以创建平滑的颜色变化过程，在这里展示了一个简单的从红色到紫色再到青色最后返回的过程。 ```python p_R.start(0) p_G.start(0) p_B.start(0) try: while True: for dc in range(0, 101, 5): # Increase duty cycle from 0 to 100% p_R.ChangeDutyCycle(dc) p_B.ChangeDutyCycle(100-dc) time.sleep(0.1) for dc in reversed(range(0, 101, 5)): # Decrease duty cycle back down p_R.ChangeDutyCycle(dc) p_G.ChangeDutyCycle(100-dc) time.sleep(0.1) for dc in range(0, 101, 5): p_G.ChangeDutyCycle(dc) p_B.ChangeDutyCycle(100-dc) time.sleep(0.1) for dc in reversed(range(0, 101, 5)): p_G.ChangeDutyCycle(dc) p_R.ChangeDutyCycle(100-dc) time.sleep(0.1) except KeyboardInterrupt: pass finally: p_R.stop() p_G.stop() p_B.stop() GPIO.cleanup() ``` #### 流水灯模式四：随机跳跃显示 每次只激活一个LED，并且按照伪随机顺序切换下一个要被点亮的LED直到遍历完所有的可能性后再重新开始一轮新的序列。 ```python from random import shuffle color_list = list(pins.keys()) shuffle(color_list) for _ in range(len(color_list)*3): # Repeat three times the length of colors. for c in color_list: GPIO.output(pins[c], GPIO.HIGH) time.sleep(0.8) GPIO.output(pins[c], GPIO.LOW) time.sleep(0.2) shuffle(color_list) # Shuffle again after each full round. GPIO.cleanup() ```