Node.js：如何延迟（不休眠）从一条线到另一条线以循环脉冲步进电机

Question

I'm controlling a stepper motor with onoff in a Raspberry Pi 3B+ and want to delay between setting pulse high and then low within a loop.

for (i=0; i < steps; i++) {
  pinPul.writeSync(1);
  delay here 10 milliseconds
  pinPul.writeSync(0);
  delay another 10 milliseconds
}

I don't want to stop the execution of any of the other stuff that's going on in the program during the delay.

Answer 1

Node.js uses a event loop. And you want to use sync functions that waits.

The default approach in js/node is using setTimeout() but it relies on callbacks and cannot be used on a for loop. To fix this you need to use the modern async/await .

async function sleep(ms) {
  return new Promise(resolve => {
    setTimeout(resolve, ms);
  });
}

async function ledLoop() {
  for (i=0; i < steps; i++) {
    pinPul.writeSync(1);
    await sleep(10);
    pinPul.writeSync(0);
    await sleep(10);
  }
}

ledLoop();

Just a comment. 10ms is too fast for the human eye. Change to 1000ms for better testing.

Answer 2

You could please help me with my code?

In the form below the code blocks until the time has passed.

I wanted to make the code to not block and executes everything else. What is the problem?

const dotenv = require('dotenv');
dotenv.config();
const preferenceService = require("../services/preference-service")
let rpio = {};
if (!process.env.DEVELOPMENT) rpio = require('rpio');

exports.irrigate = async (irrigationTimeInSeconds, sensorName) => {
    const preferences = await preferenceService.getPreference(sensorName)
    
    console.log("Pornire irigare - " + preferences.sensorName + "...")
    
    
    rpio.open(preferences.signalPin, rpio.OUTPUT, rpio.HIGH);

    async function sleep(irrigationTimeInSeconds) {
      return new Promise(resolve => {
        setTimeout(resolve, irrigationTimeInSeconds);
      });
    }

    async function irigare() {
      rpio.write(preferences.signalPin, rpio.LOW);
      await rpio.sleep(irrigationTimeInSeconds);
      rpio.write(preferences.signalPin, rpio.HIGH);
      rpio.close(preferences.signalPin);
    }

    irigare();
    
    return "Success"
} 

exports.getSensorNames = async () => {
    const preferences = await preferenceService.getPreferences()
    return preferences.map(preference => preference.sensorName)
}