Now what we’ve tried to demonstrate here is that this whole idea about tight loops is relative. Especially compared to the last couple programs. The time from the start of the loop to the end of the loop is pretty significant. You know you’re gonna be there for a minute. You get into the 12 items or less line, but then the guy in front of you pulls out his checkbook, and starts writing a check. When the Arduino gets to this line of code, it’s kind of like going to the grocery store. The whole program comes to a standstill while we wait for this delay code to finish. The code starts fast, we do the serial print, but then we get halted right there at the delay function. Is this still a tight loop? Is the time, from the start of the loop to the end of the loop, a lot of time? No, this is definitely not a tight loop. You can see below we’ve added a thousand millisecond (1 second) delay to the loop. Next let’s add a delay to this program using the Arduino delay() function. We’re printing to the serial monitor, and then we’re doing a quick check to see if a button is being pressed. ![]() Is this a tight loop? So, from the start of the loop, to the end of the loop, is that pretty quick? Is the voltage at pin five high? If so, then we print something else to the serial monitor window. So we have declared a button and used an if statement to check and see if the button has been pressed. We’ll have the program check to see if a button is pressed, and if it is, we’ll have something new sent to the serial monitor Now that we have a function here, serial print, it will take (a tiny) bit of time to print “Ice Ice Baby” to serial monitor.īut this is still a pretty quick loop. It’s worth noting, however, that this loop is not as tight as the previous example. Is this a tight loop? That is, from the start of the loop to the end of the loop, does that take a lot of time? It takes very little time, so that’s a fast, tight loop. We will start serial communication, and then print something to the serial monitor window. Said another way, the interval from the start of the loop to the finish is short (therefore it is fast, or “tight”). Since there’s nothing inside of the loop to execute, the time it takes to go thru the sketch is practically zilch. So would you consider that empty sketch a tight loop? Definitely, that’s as fast and as tight as you can make a loop. But still, that’s relatively fast (your computer processor is likely running at Gigahertz speeds… that’s billions). In fact, it’s most likely that it’s multiple instructions. So that means that 16 million instructions are happening every second on the Arduino!Įach line of code isn’t necessarily one instruction. How fast does it execute the loop? It depends on which Arduino board you’re using, but an Arduino Uno has a clock speed of 16 megahertz. It executes the first line, then it executes the second, and then the third, and so on and so forth, until it gets to the bottom. Void loop then goes through every line of code that might be inside the loop (inside these curly brackets). ![]() And as you may know, void setup only runs once, and then it hands the show over to void loop. Starting with the most basic sketch, we’ve only got two functions: void setup, and void loop. Let’s take a look at an Arduino sketch for a demonstration of a tight loop. And when we say a tight loop, what does that mean? Once you start using the millis() function, you’ll be happier, more cheerful, and gosh darn it, people will like you.įirst let’s discuss the concept of a tight loop. And the more familiar you are with using the millis function, to help you time events in your Arduino code, the easier it will be to incorporate other parts into your program later on. The cooler, snazzier option is the Arduino millis() function. So you want something to occur at a set interval and you’re looking for a solution. If your answer is using the delay function, well, you’re kind of right. Part 1 helps us understand what the millis() function does, part 2 discusses tight loops and blocking code, and part 3 discusses when the millis() function outshines the delay() function. ![]() This is part 2 of our millis() function mini-series. How do you do that? Is there a function that is simple and straightforward that helps us with this? Yes there is! We will discuss the delay function, as well as the millis() function, in the video below: Have you ever been making an Arudino project and you want something to occur at a timed interval? Maybe every 3 seconds you want a servo to move, or maybe every 1 minute you want to send a status update to a web server.
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