AVR 上使用延迟的软件 PWM
我正在尝试使用 AVR ATMega16 上的延迟来完成简单的 PWM 生成
我正在尝试做的只是将 LED 占空比从 100% 淡入淡出到 0%，稍后我将扩展它以控制双色 LED 的两种颜色有很好的效果。
我以前用 PIC 在 mikroC 中完成过此操作，但不知何故，在 avr-gcc 中它并不那么容易，或者也许我遗漏了一些东西。
我的问题是我希望 LED 在 3 秒内完全消失，但我感觉它的消失速度更快。我还认为，它在高占空比上花费的时间比在低占空比上花费的时间更多。我的意思是，我看到 LED 亮了一会儿，然后它就消失了，但是当它变得暗淡时，它会非常快地移动到不同的工作周期，所以我想......
你对我所缺少的有什么想法吗？
代码可在此处获取：http://ideone.com/lUP5f
谢谢
I am trying to accomplish a simple PWM generation using delays on an AVR ATMega16
What i am trying to do is simply fade a led from 100% to 0% duty cycle, and later i will expand it to control two colors of a bicolor led to have a nice effect.
I have done this in mikroC with PICs before, but somehow it's not as easy in avr-gcc, or maybe i am missing something.
My problem here is that i want the led to fade completely in 3 seconds, but i feel its fading faster. I also think that it's spending more time on high duty cycles than on low ones. I mean that i see the led bright for a bit, then it fades, but when it becomes dim it moves to different duty cycles very fast or so i think..
Any ideas you might have on what i am missing ?
Code is available here : http://ideone.com/lUP5f
Thanks
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可能是保险丝设置有问题。时钟通常由熔丝控制，而不是由定义控制。然而，延迟功能使用#define F_CPU。可以贴一下你的保险丝设置吗？
您想要使用延迟而不是计时器来生成 PWM 是否有特定原因？如果您想了解计时器，我可以向您推荐这些教程：1)定时器教程 2)PWM
编辑：btw
uint8_t 允许值从 0 到 255编译器通常会为此生成警告：
It may be a problem with the fuse settings. The clock is usually controlled by fuses not by the define. However the delay function uses the #define F_CPU. Can you post your fuse settings?
Is there a specific reason that you want to use delay instead of a timer to generate the PWM? In case you want to have a look at timers I can recommend these Tutorials to you:1)Timer Tutorial 2)PWM
Edit: btw
uint8_t allows values from 0 to 255 the compiler usually generates a warning for this:
问题是 LED 不是线性的。
因此，将它们打开（例如以 50% 将其亮度降低到 50%）是行不通的。
您可以使用预定义的表（例如此处：http://www.mikrocontroller.net/articles/LED-Fading#Das_Demoprogramm）
您不需要能够阅读德语。只是研究这段代码..
有一些表，例如 16 位 PWM (pwmtable_16[])。
所以你可以写：
delay_us(pwmtable_16[a]);而不是
delay_us(a);The problem is, that LEDs are not linear.
So it doesn't work to turn them on for example with 50% to reduce their brightness to 50%..
You can use a predefinied table (for example here: http://www.mikrocontroller.net/articles/LED-Fading#Das_Demoprogramm)
You don't need to be able to read german. Just study this piece of code..
There are some tables for example for 16 bit PWM (pwmtable_16[]).
So you can write:
delay_us(pwmtable_16[a]);instead of
delay_us(a);