serial.c

来自「这是arm10上面的linux环境下的串口通信源程序,方便学习和调试」· C语言 代码 · 共 75 行

#include "serial.h"
#include "pxa-regs.h"
/*
 * Initialise the serial port with the given baudrate. The settings
 * are always 8 data bits, no parity, 1 stop bit, no start bits.
 *
 */
void SerialInit(eBauds baudrate)
{
	/* Theory of operations:
	 * - Flush the output buffer
	 * - switch receiver and transmitter off
	 * - clear all sticky bits in control register 3
	 * - set the port to sensible defaults (no break, no interrupts,
	 *   no parity, 8 databits, 1 stopbit, transmitter and receiver 
	 *   enabled
	 * - set the baudrate to the requested value
	 * - turn the receiver and transmitter back on
	 */
	while((FFLSR & (0x1 << 5)) == 0) ;
	FFLCR = 0x00;
	FFLCR = 0x80;
	FFDLL = baudrate &0xff;
	FFDLH = baudrate >> 8;
	FFLCR = 0x00;
	FFLCR = 0x03;
	FFFCR = 0x00;
	FFIER = FFIER | 0x40;
}


/*
 * Output a single byte to the serial port.
 */
void SerialOutputByte(const char c)
{
	/* wait for room in the tx FIFO */
	while((FFLSR & (0x1 << 5)) == 0) ;
	FFRBR = c;
	/* If \n, also do \r */
	if(c == '\n')
		SerialOutputByte('\r');
}




/*
 * Write a null terminated string to the serial port.
 */
void SerialOutputString(const char *s) {

	while(*s != 0)
		SerialOutputByte(*s++);
		
} /* SerialOutputString */

/*
 * Read a single byte from the serial port. Returns 1 on success, 0
 * otherwise. When the function is succesfull, the character read is
 * written into its argument c.
 */
int SerialInputByte(char *c)
{
	if(FFLSR & 0x01) {
		*c = (char)FFRBR;
		return(1);

	} else {
		/* no bit ready */
		return(0);
	}
} /* SerialInputByte */