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46 lines
1.4 KiB
C
46 lines
1.4 KiB
C
#include <avr/io.h>
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#include <util/delay.h>
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#include "uart.h"
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#include <avr/interrupt.h>
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void init_clk(void)
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{
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// ========= System Clock configuration =========
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// Set to external 16Mhz crystal, using the PLL at *2
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// set it to be a 12-16Mhz crystal with a slow start-up time.
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OSC.XOSCCTRL = OSC_FRQRANGE_2TO9_gc | OSC_XOSCSEL_XTAL_16KCLK_gc ;
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OSC.CTRL |= OSC_XOSCEN_bm ; // enable it
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while( (OSC.STATUS & OSC_XOSCRDY_bm) == 0 ){} // wait until it's stable
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// The external crystal is now running and stable.
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// (Note that it's not yet selected as the clock source)
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// Now configure the PLL to be eXternal oscillator * 2
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OSC.PLLCTRL = OSC_PLLSRC_XOSC_gc | 2;
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// now enable the PLL...
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OSC.CTRL |= OSC_PLLEN_bm ; // enable the PLL...
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while( (OSC.STATUS & OSC_PLLRDY_bm) == 0 ){} // wait until it's stable
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// And now, *finally*, we can switch from the internal 2Mhz clock to the PLL
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CCP = CCP_IOREG_gc; // protected write follows
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CLK.CTRL = CLK_SCLKSEL_PLL_gc; // The System clock is now PLL (16Mhz * 2)
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// ==============================================
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}
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int main(void){
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init_clk();
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init_uart();
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PORTD.DIRSET = 1 << 5;
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sei();
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for(;;){
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char tmp = USARTD0.DATA;
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if(!tmp)
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tmp='a';
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USARTD0.DATA = tmp;
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PORTD.OUTTGL = 1 << 5;
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_delay_ms(1000);
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}
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}
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