Using two sensors with delay concurrently

Question

I want to use an ultra-sonic sensor and the led concurrently. I want the led to blink every 0.2 seconds and the ultra-sonic to measure distance without regard to the blinking.

The problem is I have the following code for blinking:

digitalWrite(13, HIGH);
delay(1000);
digitalWrite(13, LOW);
delay(200);

which makes the ultra-sonic sensor to be delayed as well, but I want it to keep measuring distance. Any tips?

Answer 1

There is a non-blocking library that works similar to delay() Virtual Delay. This sketch turns your Uno's built-in LED ON for 1 second, then OFF for 200ms, repeatedly.

#include <Arduino.h>
#include "avdweb_VirtualDelay.h"

VirtualDelay delay1, delay2;

void setup(){

  pinMode(LED_BUILTIN, OUTPUT);
  digitalWrite(LED_BUILTIN, LOW);

}

void loop(){

  // This sequence has a deadlock.
  if(delay1.elapsed()){
    digitalWrite(LED_BUILTIN, LOW);
    delay2.start(200);
  }

  if(delay2.elapsed()){
    digitalWrite(LED_BUILTIN, HIGH);
    delay1.start(1000);
  }

  // This breaks the deadlock. You can start with any
  // delay object you want e.g. delay2.start(0);
  DO_ONCE(delay1.start(0));

  // Your code here.

}

The library's author has an excellent tutorial on their website: avdweb Virtual Delay timer for Arduino.

Answer 2

You could try to use millis(). It is a timer that measures how long your program has been running. With some math, you could use millis to let your LED blink without delaying the ultra sonic sensor.