serial.c

RT-Thread是发展中的下一代微内核嵌入式实时操作系统

#include "lib.h"

#define S3C4510_BASE_ADDR	0x3ff0000
#define S3C_REG    			*(volatile unsigned int *)

#define UARTLCON0       	(S3C_REG(S3C4510_BASE_ADDR+0xd000))
#define UARTCONT0       	(S3C_REG(S3C4510_BASE_ADDR+0xd004))
#define UARTSTAT0       	(S3C_REG(S3C4510_BASE_ADDR+0xd008))
#define UARTTXH0        	(S3C_REG(S3C4510_BASE_ADDR+0xd00c))
#define UARTRXB0        	(S3C_REG(S3C4510_BASE_ADDR+0xd010))
#define UARTBRD0        	(S3C_REG(S3C4510_BASE_ADDR+0xd014))

#define	USTAT_RCV_READY		0x20   /* receive data ready */ 
#define	USTAT_TXB_EMPTY		0x40   /* tx buffer empty */

/* initializes serial */
void rt_serial_init()
{
	rt_uint32 divisor = 0;

	divisor = 0x500; /* 19200 baudrate, 50MHz */

	UARTLCON0 = 0x03;
	UARTCONT0 = 0x09;
	UARTBRD0  = divisor;

	for(divisor=0; divisor<100; divisor++);
}

/* read a character from serial without interrupt enable mode */
char rt_getc()
{
	while ((UARTSTAT0 & USTAT_RCV_READY) == 0);

	return UARTRXB0;
}

/* write a character to serial without interrupt enable mode */
void rt_putc(const char c)
{
	/*
		to be polite with serial console add a line feed
		to the carriage return character
	*/
	if (c=='\n')rt_putc('\r');

	/* wait for room in the transmit FIFO */
	while(!(UARTSTAT0 & USTAT_TXB_EMPTY));

	UARTTXH0 = (rt_uint8)c;
}

/* display a string on console */
void rt_puts(const char* str)
{
	while (*str) 
	{
		rt_putc (*str++);
	}
}

/*@}*/