Serial.begin(115200) //start Serial in case we need to print debugging info The program : unsigned long startMillis //some global variables available anywhere in the programĬonst unsigned long period = 1000 //the value is a number of millisecondsĬonst byte ledPin = 13 //using the built in LED If the period has not yet elapsed then you can go on your way and possibly do other things until the next check. Remember the principle, as laid out above "you need to record the time at which an action took place to start the timing period and then to check at frequent intervals whether the required period has elapsed." If so, you presumably want to do something, otherwise why would you be timing ?"
Let's use those variables in a program that blinks an LED, not quite the same as the example in the IDE, but one that shows the use of millis() nevertheless. We know the current value of millis(), but when did the timing period start and how long is the period ?Īt the start of the program declare 3 global variables, as followsĬonst unsigned long period = 1000 //the value is a number of milliseconds, ie 1 second We are going to need at least 2 other variables in order to determine whether the required period has elapsed.
#Arduino millis free#
Feel free to use your own name but this is the one that I will be using.
#Arduino millis code#
Simple enough, but this line of code embodies a number of important ideas : It is also convenient to do this at the start of loop() and you do it like this currentMillis = millis() Whilst it is possible to read the value each time it is required it is more convenient to read it once in each pass so that within the program its value can be used as many times as needed and that it is consistent. In order to use millis() for timing the program is going to need to know its current value, perhaps more than once in each time through loop().
#Arduino millis how to#
You know how to set the pinMode() of an input and output.In the sample programs below there are some assumptions made as follows : If so, you presumably want to do something, otherwise why would you be timing ? To use millis() for timing you need to record the time at which an action took place to start the timing period and then to check at frequent intervals whether the required period has elapsed. The principle is easy to describe but there are some gotchas along the way that you need to look out for. In this thread I will try to explain the principles of using millis() for timing and apply it to some common areas where questions arise. Between the two you should have a clearer understanding of how to use millis() for non blocking timing. The programs presented here overlap with those in that thread but I have put my own spin on using millis() and described the programs in my own way. What they need is to understand the BWod principle before they can see how to apply it to their own situation. Quite often this only serves to confuse the new user because they don't just want to blink an LED or can't get their head around doing more than one thing at (apparently) the same time. (BWoD) and/or the excellent thread entitled Several things at the same time. When this occurs the new user is usually directed to the BlinkWithoutDelay example sketch
It is not usually long before new Arduino users discover that although the delay() function is easy to use it has side effects, the main one of which is that its stops all activity on the Arduino until the delay is finished (not quite true, I know, but that is usually how the problem presents itself).
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