Delay problem in single chip microcomputer

o景天o

Delay problem in single chip microcomputer [Copy link]

I am a novice in microcontrollers. When I was writing a program, my teacher mentioned that there were too many delays in my program and it was difficult to put it into practice. He recommended the vt_time method to me, which uses a timer to do timing.

I wrote a light program here

void main()

{

system_init();

while(1)

{

led_display(); //Light flip program

vtimer_set(&vt_led, 2000); //Set the interval time
while (!vtimer_expired(&vt_led)); //Judge whether the time is up

}

}

Is it okay to write like this? I feel that the idea I wrote is the same as the delay. Will there be any difference when the MCU processes it? When the MCU processes this timing, is it still in an idling state?

dcexpert

Delay uses a single-chip microcomputer loop waiting method, which is a blocking mechanism. The system cannot process other tasks in the delay state, so the efficiency is low.

By using RTOS or timer, the corresponding task will be executed only when the set time is reached, and multiple tasks can be executed in time.

o景天o

dcexpert published on 2020-3-10 15:23 Delay uses a single-chip microcomputer loop waiting method, which is a blocking mechanism. The system cannot process other tasks in the delay state, so the efficiency is low. &nbs ...

So if I write it this way, is it still the same as using delay? The light is on, wait for the time, and then execute the next step when the time is up, and the light will flip.

sint27

o景天o posted on 2020-3-10 15:29 So if I write it this way, is it still the same as using delay? The light is on, wait for the time, and then execute the next step when the time is up, and the light flips. .

Yes, actually it is not much different from delay.

o景天o

sint27 posted on 2020-3-10 17:10 Yes, in fact, it is not much different from delay

I would like to ask, for example, how to remove the delay' (debounce) in the key detection. How to write it? And is it better if I write this LED like this?
if ((vtimer_expired(&vt_led)) //Timeout returns 1

{

led_display(); //Light flip program

vtimer_set(&vt_led, 2000); //Set the interval time

}

chunyang

The Delay instruction is used for very short delays. Longer or very long delays should be done with a timer so that the MCU can still process other tasks or enter a low power state.

huo_hu

o景天o posted on 2020-3-10 17:37 Then I would like to ask, for example, in the key detection, how to remove the delay' (debounce). How to write it. And this LED I like this...

This can

sint27

o景天o posted on 2020-3-10 17:37 Then I would like to ask, for example, in the key detection, how to remove the delay' (debounce). How to write it. And this LED I like this...

You can use a timer or time slice framework to do this. For example, you can detect a key press every 5ms and confirm that the key press is valid after several consecutive times.

眼大5子

sint27 posted on 2020-3-11 07:59 You can use a timer or time slice framework to do this, for example, detect a key press every 5ms, and confirm that the key press is valid after several consecutive presses

Generally, I don't need to delay if the time exceeds 10 us.

安之若所

o景天o posted on 2020-3-10 17:37 Then I would like to ask, for example, in the key detection, how to remove the delay' (debounce). How to write it. And this LED I like this...

Can you tell me the method?