72 lines
1.1 KiB
C
72 lines
1.1 KiB
C
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#include <avr/io.h>
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#include <stdlib.h>
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#include <avr/interrupt.h>
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//#define USART_U2X_EN
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#define F_CPU 20000000UL
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#include <util/delay.h>
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#define USART_BAUD 2400
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#define UBRR_VALUE_DS 520
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#ifndef USART_U2X_EN
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#define UBRR_VALUE (F_CPU/16/USART_BAUD-1)
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#else
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#define UBRR_VALUE (F_CPU/8/USART_BAUD-1)
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#endif
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#if !(UBRR_VALUE == UBRR_VALUE_DS)
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#warning "Calculated UBRR value differs from the value given in the datasheet: "
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#define UBRR_VALUE UBRR_VALUE_DS
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#endif
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int cnt;
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void
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usart_init(void)
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{
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UBRR0H = (unsigned char)(UBRR_VALUE >> 8);
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UBRR0L = (unsigned char)UBRR_VALUE;
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#ifdef USART_U2X_EN
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UCSR0A |= _BV(U2X0);
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#endif
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UCSR0B = _BV(TXEN0) | _BV(TXCIE0);
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UCSR0C = _BV(UCSZ00) | _BV(UCSZ01);
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//UCSR0C = _BV(UCSZ00) | _BV(UCSZ01);
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cnt = 0;
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sei();
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}
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ISR(USART_TX_vect)
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{
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if(!cnt)
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{
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UDR0 = '\n';
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cnt++;
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}
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else
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{
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cnt = (cnt + 1) % 10;
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UDR0 = '0' + cnt;
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}
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}
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int main(void)
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{
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DDRC |= _BV(PC5);
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usart_init();
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while(!(UCSR0A & _BV(UDRE0)));
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UDR0 = '0';
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while(1)
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{
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PORTC ^= _BV(PC5);
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_delay_ms(500);
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PORTC ^= _BV(PC5);
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_delay_ms(1000);
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PORTC ^= _BV(PC5);
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_delay_ms(500);
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}
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return 0;
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}
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