XMega计时器和微秒 [英] XMega Timer and Microseconds

问题描述

我正在尝试从atxmega128a3u中释放一些数据，并且需要以最快4us的速度切换一个引脚，但是到目前为止，我还没有找到一个接近它的地方...

I'm trying to bit bang out some data out of an atxmega128a3u and need to toggle a pin as fast as 4us but so far I'm not getting anywhere close to that...

在这里，我将计时器设置为88us，但是大约是146us.

Here I'm setting my timer for 88us but am getting around 146us.

    int main(void)
    {

    //CRYSTAL SETUP
        OSC_XOSCCTRL = OSC_FRQRANGE_12TO16_gc | OSC_XOSCSEL_XTAL_16KCLK_gc; // 16Mhz Crystal
        OSC_CTRL |= OSC_XOSCEN_bm;
        while(!(OSC_STATUS & OSC_XOSCRDY_bm)); //Wait for crystal to stabilize.
        CCP = CCP_IOREG_gc;
        CLK_CTRL = CLK_SCLKSEL_XOSC_gc;
        //END CRYSTAL SETUP

        cli();
        TCC0.PERL = 0x80; //88us
        TCC0.PERH = 0x05;
        TCC0.CTRLA = 0x01;
        TCC0.INTCTRLA = 0x02;
        PMIC.CTRL = 0x02;
        sei();
    }
ISR(TCC0_OVF_vect) {
   PORTF.OUTTGL = PIN3_bm;
}

如何获得更快，更准确的响应时间?

How can I get a faster and more accurate response time?

推荐答案

这是您的完整代码吗?如果是，控制器将在执行sei()之后复位；因为已经到达程序代码的末尾.在示波器上看到的延迟可能是启动时间和晶振建立时间.

Is that your complete code? If yes, the controller would reset after executing sei(); since the end of the program code has been reached. The delay you see on the oscilloscope probably is the start-up and crystal setup time.

使用

while(true); 

在主体末尾构造. 我在这里放置了volatile NOP指令，以防止编译器优化空的wh​​ile循环.如果循环中还有其他代码，则可以忽略它.

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