Pattern for doing 2 things at once.

Using Arduino Programming Questions
#1

I'm brand new to Arduino, but have a .Net development background.

What is the pattern that would be used if you want to pulse a LED (On for 1 sec, off for 1 sec), but at the same time, sound a buzzer every 300ms (On for 33ms, off for 300ms).

Because of the delay(1000) on the LED, the loop can't really handle the buzzer on/off. This is a threading issue, which I believe we have no threading.

So is there a pattern to handle this sort of situation?

It sounds like using delay in the loop is too blocking. Maybe some other timer? Spinning off a buzzer class that gets called to see if a change in the buzzer status should happen, and then loop has no delay... just Buzzer.Update() and MyLed.Update() and those methods somehow check a timer?

#2

Take a look at Using millis() for timing. A beginners guide, Several things at the same time and look at the BlinkWithoutDelay example in the IDE.

#3

I have found this youtube video useful for understanding blink without delay for two independent blinks.

#4

UKHeliBob:
Take a look at Using millis() for timing. A beginners guide, Several things at the same time and look at the BlinkWithoutDelay example in the IDE.

Thanks! That is a fantastic post! Reading now... and it makes sense... Thanks.

#5

Cralis:
Thanks! That is a fantastic post! Reading now... and it makes sense... Thanks.

So basically, here you are the OS, you yourself will handle the threads slicing.

#6

I wonder if anyone has ever counted what % of forum questions relate to this? Probably about 90%. And another 90% is about servo power, and let's not forget the 90% about switch edge detection.

#7

neiklot:
I wonder if anyone has ever counted what % of forum questions relate to this? Probably about 90%. And another 90% is about servo power, and let’s not forget the 90% about switch edge detection.

I don’t believe any of those figures.

A recent study showed that 84% of all statistics quoted on the Web are invented to suit the poster’s case :slight_smile:

#8

UKHeliBob:
A recent study showed that 84% of all statistics quoted on the Web are invented to suit the poster's case :slight_smile:

LOL

...R

#9

Thanks guys. I followed that example of using millis and have a flashing and fading LED. That’s way better.

I fear it could get quite complex. But much better nevertheless. I’ll try with an input next.

Great help. Thanks.

#10

Cralis:
I fear it could get quite complex.

It will, but so what if you have a zillion previousMillisRedLed and previousMillisLeftMotor and so on... you can manage them all from calls in loop() and keep everything tidy.

There are also a couple of "blink without delay in a box" examples around, such as this Flasher class at adafruit.

#11

Thanks nieklot! Just read that. Looking forward to now trying the more improved OOP version of my millis demo I’ve made. Thats going to make life a lot easier. Great article once again. Thanks for the link.

#12

As they say there "Put a little OOP in your loop"

#13