The microcontroller has its own PWM to control the brightness of the LED light. How to write it? ?

一百年后的自己

The microcontroller has its own PWM to control the brightness of the LED light. How to write it? ? [Copy link]

 

The register configuration has been configured. I just started learning microcontrollers and just came into contact with PWM. Now the register configuration is done, but how can the LED turn on and off later? I don't know how to write it.

I also know that the time that the high level occupies the entire cycle is the duty cycle. But how should it be written? ? ? ? ? ? ? ? ? ? Help! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !

29447945

Add a while (1) loop, change the duty cycle from 0 to 100 every 100ms, and the light will normally change from on to off.

一百年后的自己

29447945 Published on 2019-10-17 17:26 Add a while (1) loop, change the duty cycle at intervals of a certain period of time, such as 100ms, from 0 to 100 duty cycle, the light will normally change from bright to dark

I tried it. It didn't work. I changed the value manually.

29447945

Myself One Hundred Years Later posted on 2019-10-17 17:47 I tried it. It didn't work. I changed the value manually

Did you add a delay?

huo_hu

Just modify the duty cycle register

huo_hu

Is the configuration register locked?

一百年后的自己

29447945 posted on 2019-10-17 21:34 Is there a delay?

No addition

一百年后的自己

huo_hu posted on 2019-10-18 08:16 Is the configuration register locked?

Can I just edit this part?

29447945

Myself One Hundred Years Later was published on 2019-10-18 09:06 No

Each time you change the duty cycle, you have to delay it, otherwise you won't be able to see the change at all.

一百年后的自己

29447945 Published on 2019-10-18 09:10 Every time you change the duty cycle, you need to delay it, otherwise you can't see the change process at all

This is the register configuration I just changed.

Does each change of duty cycle require a delay?

一百年后的自己

29447945 Published on 2019-10-18 09:10 Every time you change the duty cycle, you need to delay it, otherwise you can't see the change process at all

Then I put it in the main function, and the while loop is fine. I also declared variables for the period and duty cycle. Changing the values in the main function should have an effect. But I didn't declare the change.

29447945

Myself a hundred years later posted on 2019-10-18 09:38 Then I put it in the main function, while looping all the time, right? And I declared variables for period and duty cycle, and then in the main function...

Here is the idea, you have to implement these functions yourself.

void main()

{

int pwm_value = 0;

pwm_init();

while(1)

{

set_pwm(pwm_value );

pwm_value += 10;

if(pwm_value >= 100)

pwm_value = 0;

delay_10ms();

}

}

一百年后的自己

29447945 Published on 2019-10-18 09:50 Here is the idea, you have to implement these functions yourself. void main() { int pwm_value = 0; pwm_init(); ...

OK, thanks

一百年后的自己

29447945 Published on 2019-10-18 09:50 Here is the idea, you have to implement these functions yourself. void main() { int pwm_value = 0; pwm_init(); ...

If I don't set the function at the beginning, and I directly change the duty cycle value, will the brightness of the LED lamp change? ? ? ? ? ? ?

29447945

Myself a hundred years later posted on 2019-10-18 11:24 If I don't set the function at the beginning, and I directly change the value of the duty cycle, will the brightness of the LED light change? ??? ??? ??? ???

Of course, you have to set the timer first, and then change the duty cycle. If you don't set the timer, it won't work. The delay time can be extended.

一百年后的自己

29447945 Published on 2019-10-18 12:17 Of course, you have to set the timer first, and then change the duty cycle before you can use it. If you don't set the timer, it won't work. The delay time can be extended a bit

The timer has been set, but now I have another question. I used an oscilloscope to see high and low levels.

The main thing is whether I need to use io to control the LED light after I configure the register.

Or can PWM directly dim the LED? If it can be dimmed directly, why doesn't the LED light up after I program it? I also turned on the PWM enable.

3312856

PWM can directly brighten and dim the LED, which is related to the driving lamp circuit.

3312856

Your PWM changes the switching time of the driving circuit within a unit of time, thereby adjusting the voltage of the driving circuit. The voltage changes the brightness of the lamp.