usartsend9bit.c

AVR单片机系列的ATmega162的USART编程

#include <avr/io.h>

void DelayMs(long int s);
void USART_Init(unsigned int baud);
void USART_Transmit(unsigned int data);

int main(void)
{

	DDRA=0x00;
	DDRC=0xff;
	
	USART_Init(25);
	

	while(1)
	{
		
		if((PINA&0x0F)!=0x0F)
		{
					if(!(PINA&0x01))
					{
						USART_Transmit('A'|(1<<8));
						PORTC&=~1;
					}
					else if(!(PINA&0x02))
					{
						USART_Transmit('B'|(1<<8));
						PORTC&=~(1<<1);
					}
					else if(!(PINA&0X04))
					{
						USART_Transmit('C'|(1<<8));
						PORTC&=~(1<<2);
					}
					else if(!(PINA&0x08))
					{
						USART_Transmit('D'|(1<<8));
						PORTC&=~(1<<3);
					}
		
			DelayMs(50);
		}
		PORTC=0xff;
	}


}

void USART_Init(unsigned int baud)
{
	
	UBRR1H = (unsigned char)(baud>>8);
	UBRR1L = (unsigned char)baud;
	
	UCSR1B|=(1<<RXEN1)|(1<<TXEN1)|(1<<UCSZ12);
	
	UCSR1C|=(1<<URSEL1)|(3<<UCSZ10);

}
void USART_Transmit(unsigned int data)
{
	while((UCSR1A&(1<<UDRE1))==0)
		;
	UCSR1B&=~(1<<TXB81);
	if(data&0x0100)
		UCSR1B|=(1<<TXB81);
		
	UDR1=data;
}


void DelayMs(long int s)
{
	int t;
	while(s--)
	{
		for(t=1000;t>0;t--)
			;
	}
}