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?

• ratchet freak: look up blink without delay. Which will tell you how to do things concurrently.
• Jot: The NewPing library does not use pulseIn. With the blink-without-delay ( arduino.cc/en/Tutorial/BlinkWithoutDelay ) for the led and the NewPing (it is in the library manager) for the ultra-sonic sensor, you can do many other things as well, but don't use delay in the sketch anymore.

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.