Arduino while loop timer

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Arduino while loop timer

By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I've not been programming for long and I just want to expand from electronic engineering with an Arduino UNO board.

If the global value equals 0 and the valid knock patter is true then flash a yellow LED 4 times using millis rather than delay so that it can still 'listen'. If another valid knock pattern is not heard within 6 seconds it will time out and reset global to 0 so that it can acknowledge the initial true pattern and flash the yellow LED. If the counter equals 1, wait for another valid knock pattern and if true within 6 seconds, increment the counter again and don't flash the yellow LED.

This project was inspired by the test panels used on passenger airplanes. I've seen them a lot and thought it would be a good place to start and learn about timing.

There are a few problems as I don't wish to reset millis every time and I'm using a button rather than the boolean within the knock detection script so I don't get lost in the code. I understand this won't respond 50 seconds later and it's a beginners mistake but proves what I've got if I hold down the button.

That is a lot to wade through so I may not understand your question but the bit of code below stands out as a problem:. Do you understand that there is no "resetting" of millis possible and that is merely a function that returns the number of milliseconds since the program launched? It will continue to increase as long as the program is running until it rolls over but that is a separate problem.

So a typical way millis is used to track time is, in setupto store it's current value into a variable and add your timeout period value to it:. Also be careful using delay - it is easy to use for flow control but for any program with more than one thing going on it can lead to confusing and hard to solve problems. Oh - there are more sophisticated ways of doing timing using the built-in timers on the chip to trigger interrupts but better to get the hang of things first.

I know there's delay used within the flashes but that will be changed to millisI'm just trying to get the basic function and understanding. Please be carefull with millis as they rollover after some time. Learn more. Arduino 'time out' function using a millis timer Ask Question. Asked 7 years, 1 month ago. Active 3 months ago. Viewed 20k times. If another valid knock pattern is heard withing 6 seconds, increment a counter.

Otherwise, time out and reset all values. And so on until if the counter is greater than or equal to 4 trigger the master LED array. Problems This project was inspired by the test panels used on passenger airplanes. Any help would be greatly appreciated! Matthew Murdoch Active Oldest Votes. Would nextUpdate and nextTimeout be defined before setup as an unsigned long?

Or is the nextTimeout a typo? Should be nextUpdate and yes, it would be an unsigned long. I've added a new code based off of what I learnt from your help below, new, slight I hope problem I've come up with the following sketch after playing around with your help.Timer interrupts allow you to perform a task at very specifically timed intervals regardless of what else is going on in your code.

Jump straight to step 2 if you are looking for sample code. Some commands take longer than others to execute, some depend on conditional statements if, while Arduino timer interrupts allow you to momentarily pause the normal sequence of events taking place in the loop function at precisely timed intervals, while you execute a separate set of commands.

Once these commands are done the Arduino picks up again where it was in the loop. Measuring an incoming signal at equally spaced intervals constant sampling frequency Calculating the time between two events Sending out a signal of a specific frequency Periodically checking for incoming serial data much more Lilypad, Duemilanove, Diecimila, Nano Did you use this instructable in your classroom?

Add a Teacher Note to share how you incorporated it into your lesson. The Uno has three timers called timer0, timer1, and timer2. Each of the timers has a counter that is incremented on each tick of the timer's clock. CTC timer interrupts are triggered when the counter reaches a specified value, stored in the compare match register.

Once a timer counter reaches this value it will clear reset to zero on the next tick of the timer's clock, then it will continue to count up to the compare match value again. By choosing the compare match value and setting the speed at which the timer increments the counter, you can control the frequency of timer interrupts.

The first parameter I'll discuss is the speed at which the timer increments the counter. The Arduino clock runs at 16MHz, this is the fastest speed that the timers can increment their counters. In many situations, you will find that setting the counter speed to 16MHz is too fast.

Timer0 and timer2 are 8 bit timers, meaning they can store a maximum counter value of Timer1 is a 16 bit timer, meaning it can store a maximum counter value of Once a counter reaches its maximum, it will tick back to zero this is called overflow. Clearly, this is not very useful if you only want to interrupt once a second. Instead you can control the speed of the timer counter incrementation by using something called a prescaler.

As indicated in the tables above, the prescaler can equal 1, 8, 64,and One last thing to note- certain timer setups will actually disable some of the Arduino library functions.

Timer0 is used by the functions millis and delayif you manually set up timer0, these functions will not work correctly. Additionally, all three timers underwrite the function analogWrite.

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Manually setting up a timer will stop analogWrite from working.Sometimes you want everything in the program to stop while a given condition is true. You can do this using a while loop. This example shows how to use a while loop to calibrate the value of an analog sensor. In the main loop, the sketch below reads the value of a photoresistor on analog pin 0 and uses it to fade an LED on pin 9. But while a button attached to digital pin 2 is pressed, the program runs a method called calibrate that looks for the highest and lowest values of the analog sensor.

Arduino Tutorial: Using millis() Instead of delay()

When you release the button, the sketch continues with the main loop. This technique lets you update the maximum and minimum values for the photoresistor when the lighting conditions change.

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Connect your analog sensor e. Connect your button to digital pin, again with a 10K ohm resistor to ground.

arduino while loop timer

Connect your LED to digital pin 9, with a ohm resistor in series. For more circuit examples, see the Fritzing project page. While the pushbutton is pressed, the sketch runs the calibration routine. This is a variation on the calibrate example.

Arduino or Genuino Board pushbutton or switch photoresistor or another analog sensor 2 10k ohm resistors breadboard.Pages: [1]. Making a while-loop timeout. I am new to this forum, so bare with me. For some time now I have been doing a project for my chickencoop. Evrything works as intended. I would like to incorporate a timeout function for my "Door Down" and "Door Up" function in case of reed switch failiure or some other fault with the door. I understand i have to incorporate a millis function in my while-loop, but im having trouble with understanding how to construct the code.

Code: [Select]. Re: Making a while-loop timeout.

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The art of getting good answers lies in asking good questions. Save the millis value before the door moves. Then, each time through the while loop check whether the current millis value minus the start value is greater than the required interval. If so then exit the while loop. If not then go round the while loop again. Please do not send me PMs asking for help. Post in the forum then everyone will benefit from seeing the questions and answers. Just use IF and allow loop to do the iteration.

That way you will only need to call Blynk. For the timing issue have a look at how millis is used to manage timing without blocking in Several things at a time. Note how each function runs very briefly and returns to loop so the next one can be called. And there may be dozens of calls to a function before it is actually time for it to do anything. Two or three hours spent thinking and reading documentation solves most programming problems. The correct way to busy wait for a time is: Code: [Select].

I understand that my while-loops are actually delaying my program while nyhet are locked in the loop. I understand that "howLongToWait" must be declared and sett to desired value earlier on.

Something like this? Quote from: PaulS on Oct 17,pm. Quote from: BulldogLowell on Oct 17,pm. Quote from: tomrudin on Oct 17,pm. Quote from: Robin2 on Oct 17,pm.Pages: [1]. Megagon Guest.

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Hi I've read that apparently you shouldn't use delays in an interrupt, but I've found for the simple light game I'm working on at the minute they seem to do the job. I have noticed that the length of the delays in an interrupt seems to be shorter then that of one outside an interrupt though, and I have no idea why this might be. Does anyone know why this might be happening, and if there's a better option then using delays?

Also, I've currently got a while loop with a for loop inside of it. Is there any way I can get the function to break out of the while loop with an interrupt, without it trying to finish the for loop first?

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Please read this discussion: Here. No technical PMs. If you are asked a question, please respond with an answer. If you are asked for more information, please supply it.

Arduino Workshop - Chapter Three - WHILE Loops

If you need clarification, ask for help. Do you know this tutorial?

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It helped me a lot. I've done lots of realtime programming, and the use of the Arduino delay together with timer interrupts seems to sometimes work, and often not. Many times the programming problems don't appear to be related to the timing components, but then when I rearrange things to get rid of the Delay function, things straighten out.

So I think the long and short of it is, many times, it will work. Sometimes, things go funny on you. Best to just develop the habit of avoiding it. If you need a delay, build your own clock out of one of the timers.

That way you have complete control of it. Good Luck. PaulVdB Jr. A very simple way to create a non super-accurate! Of course if an interrupt occurs while processing this line, the "delay" will take longer, but in some cases this might be even an advantage AWOL Guest. Or the optimiser might just remove the obviously pointless loop entirely, and you get no delay whatsoever.

arduino while loop timer

ISRs should be designed to complete as quickly as possible. The demo Several Things at a Time illustrates how to use millis to manage timing without blocking.

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Two or three hours spent thinking and reading documentation solves most programming problems. If you need to exit both the for loop and the containing while loop then you need to set a variable in the for loop which will cause the while loop to exit.A well known Arduino function is delay which pauses the program for an amount of milliseconds specified as parameter. At first glance you may doubt the usefulness of this function. If you want your code to just pause for ms at the end of each loop iteration, the code above is a bit silly.

The only difference between the code above and a code with delay at the end is that the loop in the above code will run quite accurately once each second. The loop in a code with delay will run a bit less frequent since it also takes some time to execute Serial.

Code-wise, we covered this in the last chapter. With millis we can ensure that the loop runs as often as we want, regardless of the execution time obviously as long as the execution time is less time the desired period.

With delay this is not possible since we do not know how long the loop execution time is. Accurate timing like this is very useful when sampling at a certain frequency or running filters, among other things.

This is not possible with delay since it pauses the entire code. This is a nice and easy way to synchronize executions in your code. You are able to run other code simultaneously as well. Just like delay has a microsecond-version called delayMicrosecondsmillis has micros. If you need better resolution, micros may be the way to go. More importantly: to learn how you can avoid the overflow issue alltogether, read this blog post. Stay tuned for more Arduino-related content in the future as well! October 15th — Updated with link to blog post about avoiding the potential overflow issue.

January 9th — Edited the code with some inputs from Dimitris from CityLab.

arduino while loop timer

Timing issues are often present in programming. Related Posts.Using delay causes your system to be stuck while waiting for the delay to expire. However replacing delays requires some care. This page explains in a step by step way how to replace Arduino delay with a non-blocking version that allows you code to continue to run while waiting for the delay to time out.

Here are a number of simple sketches each of which turn a Led on when the Arduino board is powered up or reset and then 10sec later turns it off. The first one is an example of how you should NOT write the code. The second is an example of code the works and the third is an example of using the millisDelay library to simplify the code. There are also examples of single-shot and repeating timers. If you already understand why you should not use delay and are familiar with Arduino, the importance of using unsigned longs, overflow and unsigned subtraction, then you can just skip to Using the millisDelay library Step 4.

The millisDelay library provides functionality delays and timers, is simple to use and easy to understand for those new to Arduino. This instructable is also on-line at How to code Timers and Delays in Arduino. Did you use this instructable in your classroom? Add a Teacher Note to share how you incorporated it into your lesson. In the setup method, which Arduino calls once on starting up, the led is turned on. Once setup is finished, Arduino calls the loop method over and over again.

This is where most of you code goes, reading sensors sending output etc. In the sketch above, the first time loop is called, the delay stops everything for 10secs before turning the led off and continuing. If you run this code you will see that the Run Other Code is not printed out for 10sec after the startup, but after the led is turned off ledOn equals false then is printed out very fast as loop is called over and over again.

The point to note here is that you really should not the delay function at all in the loop code. It is sometimes convenient to use delay in the setup code and you can often get away with very small using very small delays of a few milliseconds in the loop code, but you really should avoid using the at all in the loop method.

The previous sketch used a blocking delay, i. This next sketch shows you how to write a non-blocking delay that allows the code to continue to run while waiting for the delay to expire.

In the sketch above, in the setup method, the delayStart variable is set to the current value of millis. It starts as 0 each time the board is reset and is incremented each millisecond by a CPU hardware counter. More about millis later. Each time loop is called the code checks a that the delay is still running, and b if the millis has move on mS 10sec from the value stored in delayStart. When the time has move on by mS or more, then delayRunning is set to false to prevent the code in the if statement being executed again and the led turned off.

If you run this sketch, you will see Run Other Code printed out very quickly and after 10sec the Led will be turned off and if you are quick you might just see the Turned LED Off message before it scrolls off the screen. If you are familiar with unsigned longs, overflow, unsigned arithmetic and the importance of using an unsigned long variable, then you can just skip to Step 4 Using the millisDelay library.

The delayStart variable and number returned from the millis built-in function is an unsigned long. That is a number from 0 up to 4, If you add 1 to an unsigned long holding the maximum value of 4, the answer will be 0 zero. That is the number overflowed and wrapped around back to 0. You can imagine the overflow bit just gets dropped. This means, eventually, when the cpu adds one more it variable holding the millis result it will wrap around to 0.


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