millis() is a function that just returns the amount of milliseconds that have elapsed since the Arduino board began running the current program without freezing the program. To overcome the problem caused by using delay, a developer should use millis() function which is easy to use once you become habitual and it will use 100% CPU performance without generating any delay in executing the instructions. You can go through and check this out to make it more clear. The official documentation of Arduino clearly mentions this in its Notes and Warnings of delay() function description. But when we use delay(), if the user is pressing the first button then the program will stop for 2 seconds and if the user presses the second button before 2 seconds delay, then the microcontroller won’t accept the input as the program is in halt stage. So if one push button is pushed then the corresponding LED should glow for 2 seconds, similarly if second is pushed then LED should glow for 4 seconds. Consider we want to toggle two LEDs using two push buttons. The best example to explain the drawback of delay function is using two push buttons. This hampers the performance of the microcontroller in terms of speed and executing the instructions. Similarly if the delay is 10 seconds then program will stop for 10 seconds and processor will not allow to go for the next instructions until the 10 seconds passed. So if we are giving a delay of 1 second then the processor cannot go to next instruction until 1 second passed. Here comes the point, both functions pause the program for the amount of time passed in delay function. if we write delayMicroseconds(1000), then the delay will be of 1000 microseconds i.e. Similarly in delayMicroseconds() function, the parameter passed is in microseconds i.e. The only difference is that, in delay() function, the parameter integer passed is in milliseconds i.e if we write delay(1000) then the delay will be of 1000 milliseconds i.e. Both functions are identical in terms of generating delay. If the reference documentation of Arduino is considered then there is two type of delay functions, the first one is delay() and second is delayMicroseconds(). But before starting let's discuss that why we should not use delay() function in any project.
Arduino also has a delay() function which is used widely. Since the Arduino runs in low frequency and RAM compare to Laptop/Mobile/PC so the time given to each task will also be different.
The concept will be almost same for the Arduino Multitasking, except the time distribution will be a bit different. This is how the multitasking is done in most of the systems. Let’s discuss how OS manages multitasking.Īs seen in the picture, the CPU divides the time in the three equal parts and assign each part to each task/application. The end user use all these applications at the same time but OS takes this concept a bit different. The good example of multitasking in computers are when users run the email application, internet browser, media player, games, at the same time and if users don’t want use the application it runs in the background if not closed.
#ARDUINO MILLIS SOURCE CODE PC#
The MOS can be mobile or desktop PC Operating System. This kind of operating systems are known as MOS (multitasking operating system). Almost all operating systems feature multitasking. Multitasking simply means executing more than one task or program simultaneously at the same time. Before going into detail let’s start with understating Multitasking. So this article explains how we can avoid use of delay() function and replace it with millis() to perform more than one tasks simultaneously and make the Arduino a Multitasking controller. Here in this tutorial we will learn How Arduino performs Multitasking with Arduino millis function. Generally a delay() function is used in Arduino for a periodic task like LED Blinking but this delay() function halt the program for some definitive time and don’t allow other operations to perform. In embedded systems, microcontrollers can also handle Multitasking and performs two or more tasks simultaneously without halting the current instructions. The multitasking has led the computers to a revolution where one or more programs can run simultaneously which increases efficiency, flexibility, adaptability and productivity.
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