serial.c

一个基于MMU的操作系统

#include <s3c2410.h>
#include <serial.h>
 
#define	TXD0READY	(1<<2)
#define	RXD0READY	(1)

void init_uart(void)
{//初始化UART
	int i = 0;
	GPHCON |= 0xa0;		//GPH2,GPH3 used as TXD0,RXD0
	GPHUP	 = 0x0c;		//GPH2,GPH3内部上拉

	ULCON0	 = 0x03;		//8N1	
	UCON0	 = 0x245;		//查询方式
	UFCON0 = 0x00;		//不使用FIFO
	UMCON0 = 0x00;		//不使用流控
	UBRDIV0 = 53;		//波特率为57600(PCLK=50MHz)
				//UBRDIV0=(int)(PCLK/(bps*16))-1
	for(; i < 10000; i++);
}

void putc(unsigned char c)
{
	while( ! (UTRSTAT0 & TXD0READY) );
	UTXH0 = c;
}

unsigned char getc(void)
{
	while( ! (UTRSTAT0 & RXD0READY) );
	return URXH0;
}

int printk(unsigned char* str)
{
	int i = 0;
	while( str[i] ){
		putc( (unsigned char) str[i++] );
	}
	return i;
}