Node.js & Raspberry Pi & WS2812B RGB LEDs strip All In One

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Node.js & Raspberry Pi & WS2812B RGB LEDs strip All In One

Node.js & Raspberry Pi & WS2812B RGB LED 灯带

Node.js

onoff

To interface with the GPIO on the Raspberry Pi using Node.js, we will use a Module called "onoff".

# install
$ npm install onoff

https://www.npmjs.com/package/onoff

https://github.com/fivdi/onoff

//include onoff to interact with the GPIO
var Gpio = require('onoff').Gpio;
var LED = new Gpio(18, 'out');


function blinkLED() { //function to start blinking
  if (LED.readSync() === 0) { //check the pin state, if the state is 0 (or off)
    LED.writeSync(1); //set pin state to 1 (turn LED on)
  } else {
    LED.writeSync(0); //set pin state to 0 (turn LED off)
  }
}

//run the blinkLED function every 500ms
var blinkInterval = setInterval(blinkLED, 500);

function endBlink() { //function to stop blinking
  clearInterval(blinkInterval); // Stop blink intervals
  LED.writeSync(0); // Turn LED off
  LED.unexport(); // Unexport GPIO to free resources
}

setTimeout(endBlink, 3000); //stop blinking after 3 seconds

https://www.npmjs.com/package/rpi-ws281x-native

pigpio

# 依赖项 pigpio C library
$ sudo apt-get update
$ sudo apt-get install pigpio

# version
$ pigpiod -v

https://github.com/joan2937/pigpio

$ npm install -S pigpio

https://www.npmjs.com/package/pigpio

https://github.com/fivdi/pigpio

const Gpio = require('pigpio').Gpio;

const PIN = 17;
const led = new Gpio(PIN, {mode: Gpio.OUTPUT});

// PWM 占空比
let dutyCycle = 0;

setInterval(() => {
  led.pwmWrite(dutyCycle);
  dutyCycle += 5;
  if (dutyCycle > 255) {
    dutyCycle = 0;
  }
}, 20);

https://www.npmjs.com/package/pigpio#pulse-an-led-with-pwm

GPIO

General Purpose Input Output

Breadboard

面包版电路连通图解

demos

GPIO channel 占用 bug ❌

RuntimeWarning: This channel is already in use, continuing anyway. Use GPIO.setwarnings(False) to disable warnings.

$ ./gpio.py 3
arg1 = 3
⏰ current datetime = 2023-05-13 00:37:25
/home/pi/Desktop/node-led/./gpio.py:28: RuntimeWarning: This channel is already in use, continuing anyway.  Use GPIO.setwarnings(False) to disable warnings.
  GPIO.setup(PIN, GPIO.OUT)
n = 3
开始闪烁⏳
i = 0
i = 1
i = 2
结束闪烁 👌🏻

https://raspberrypi.stackexchange.com/questions/55143/gpio-warning-channel-already-in-use

http://raspi.tv/2013/rpi-gpio-basics-3-how-to-exit-gpio-programs-cleanly-avoid-warnings-and-protect-your-pi

GPIO.cleanup() 将您在 RPi.GPIO 中使用的任何 GPIO 设置为 INPUT 模式。
如果该行为是可取的，请在退出脚本之前调用该方法

GPIO.cleanup()

#!/usr/bin/env python3
# coding: utf8

import RPi.GPIO as GPIO

from datetime import datetime
import time
import sys

arg1 = sys.argv[1]
print("arg1 =", arg1);

# shell 获取时间戳 ✅
# SH_DATE=$(TZ=':Asia/Shanghai' date '+%Y-%m-%d %T');
# datetime = $(date '+%Y-%m-%d %T')

# Python 获取时间戳 ✅
now = datetime.now()
# 转换为指定的格式
currentTime = now.strftime("%Y-%m-%d %H:%M:%S")
print("⏰ current datetime =", currentTime);

# $ pinout 命令查看，或 https://pinout.xyz/
# 指定 BCM 模式下的 GPIO 针脚编号是 12
# 对应的物理针脚编号是 32
PIN = 12
# BCM 模式
GPIO.setmode(GPIO.BCM)

# 指定 GPIO 针脚为一个电流输出针脚
GPIO.setup(PIN, GPIO.OUT)
# 输出低电平
GPIO.output(PIN, GPIO.LOW)

# index
i = 0
# 类型转换，str => int
n = int(arg1)

print("n =", n)
print('开始闪烁⏳')

while (i < n):
  print("i =", i)
  # 高电平，LED 点亮
  GPIO.output(PIN, GPIO.HIGH)
  # 休眠 1 秒，防止 LED 长时间点亮烧坏了
  time.sleep(1.0)
  # 低电平，LED 熄灭
  GPIO.output(PIN, GPIO.LOW)
  # 休眠 1 秒
  time.sleep(1.0)
  i = i + 1

# 输出低电平，LED 关闭
# GPIO.output(PIN, GPIO.LOW)
# 清除，释放内存
GPIO.cleanup()

print('结束闪烁 👌🏻')

poweroff

$ sudo reboot
$ sudo shutdown -h now

PCB Design Software

Fritzing

https://fritzing.org/

refs

https://www.w3schools.com/nodejs/nodejs_raspberrypi.asp

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