How can I run multiple loops at the same time with an Arduino?

See the discussion here: http://www.element14.com/community/message/129449/l/re-multiple-arduino-functions-without-delay

Basically just check the millisecond timer and call a couple of functions at the appropriate times - one function to do the fading for one LED, and the other to do the blinking for the other LED.

There is more detail in that discussion thread.

Hello,

to run multiple loop at the same time, independently, you should ... NOT use a second loop !

The loop() function in the Arduino program skeleton is a sort of "fake"; as a matter of fact it is only a way to tell the CPU "do this sequence indefinitely", but it is not covering the loop following the concept for(..) { } as it is usually intended in C/C++ programming. So first of all forget this vision.

Another thing that is too frequently used but as a matter of fact is more a damage than an advantage is the Delay(). It is a function blocking the processor for a certain period, so it is not the worth to use it in your case, but I suggest to never use the Delay() in programs excluding when you are doing tests to see if a certain part works.

Instead you should use a counter. If you initialise a long int global variable you can read the time of the processor in every moment without stopping the execution of the entire program.

long timeCounter; // milliseconds counter
long timePassed; // The actual milliseconds time

// We need a "loop" doing event 1 every 10 ms, one doing event 2 every 5 ms
// and one doing event 3 every 25 ms
long delay1 = 10;    // ms for cycle of event 1
long delay2 = 5;     // ms for cycle of event 2
long delay3 = 25;    // ms for cycle of event 3

// Counters for the number of triggered events before the
// corresponding event starts
int countEvent1, countEvent2, countEvent3;

int TRIGGER = 5; // ms to trigger the milliseconds timer

int MAX1 = 2; // Number or triggered milliseconds to start event1
int MAX2 = 1; // Number or triggered milliseconds to start event2
int MAX3 = 5; // Number or triggered milliseconds to start event3

// Initialisation
setup {
     timeCounter = millis(); // read the actual internal time
     timePassed = 0; // we start with no time passed

     countEvent1 = 0;
     countEvent2 = 0;
     countEvent3 = 0;
}

// Infinite cycle
loop() {

     // Read the actual time
     timePassed = millis() - timeCounter;
     // The smallest unit of time that should trigger an event is for event 2 (5 ms)
     // so our trigger should count this smaller unit

     // Check if the time passed after last reading is the trigger time
     if(timePassed >= TRIGGER) {
          // It's time to manage the events
          if(++countEvent1 == MAX1){
               // Reset the trigger and start the event
               event1();
               countEvent1 = 0;
          } // Event 1 ???
          
          // It's time to manage the events
          if(++countEvent1 == MAX2){
               // Reset the trigger and start the event
               event2();
               countEvent2 = 0;
          } // Event2 ???

          // It's time to manage the events
          if(++countEvent3 == MAX3){
               // Reset the trigger and start the event
               event3();
               countEvent3 = 0;
          } // Event3 ???

     } // Trigger ??

} // LOOP

// ============ Event functions

event1() {
// Add the code for your event
}

event2() {
// Add the code for your event
}

event3() {
// Adde the code for your event
}

The IMO poorly worded example  " BlinkWithouDelay" shows how to achieve waht Shabaz has pointed you to.

I use an analogy of filling a paddling pool.

You can stand there holding the hose until it is full.

You can't do anything else ... which is what Delay() does.

OR

You can start the filling and come back at regular intervals.

You note the time and decide to come back 5 mins later to see if it is full.

Meanwhile you are free to do other things ...this is where the use of the Millis() timeer comes in.

Mark

some ideas on how it is possible to avoid this?

The best you can do is mark other answers useful ....

There are many methods to achieve a result, and some will argue this is the best way, others will argue this way.

As far as I am concerned, if the OP understands the concept, and the result does what they want, then they can refine or improve on it when they need to.

IMO writing short cryptic code just because it runs faster is a waste of energy if it just sits there waiting, and is difficult to understand.

mark

Mark,

IMO writing short cryptic code just because it runs faster is a waste of energy if it just sits there waiting, and is difficult to understand.

I have not understood if you refers in general or to my example in this question.

Enrico

No ones example, just that there are often several different ways to do something.

One might have lots of comments and do extra manipulation, while other methods might be one or two lines.

I have found that new comers sometimes get focused on the code, and don't understand what the concept is  ... hence the pool example.

Once you understand WHAT you are trying to achieve, it is often easier to understand the solution or answers provided.

In your example you use the 'long' declaration but a new comer doesn't understand why unless you point it out  ... yes they could look it up, but will they.

Sometimes we forget that it has become second nature to us, but for anyone new they are still learning ...

It's not unlike driving a car when you are teaching someone who has never done it.

Does that make sense

Mark

Hi Andrew

Have you got this working yet?