serial.c

RT-Thread是发展中的下一代微内核嵌入式实时操作系统

/*
 * File      : serial.c
 * This file is part of RT-Thread RTOS
 * COPYRIGHT (C) 2006, RT-Thread Development Team
 *
 * The license and distribution terms for this file may be
 * found in the file LICENSE in this distribution or at
 * http://openlab.rt-thread.com/license/LICENSE
 *
 * Change Logs:
 * Date           Author       Notes
 * 2006-08-23     Bernard      first version
 */

#include <rthw.h>
#include <rtthread.h>

#include "AT91SAM7X.h"

#define AT91C_US_RXRDY			((unsigned int) 0x1 <<  0)	/* US RXRDY Interrupt */
#define AT91C_US_TXRDY			((unsigned int) 0x1 <<  1)	/* US TXRDY Interrupt */
#define AT91C_US_RSTRX			((unsigned int) 0x1 <<  2)	/* US Reset Receiver */
#define AT91C_US_RSTTX			((unsigned int) 0x1 <<  3)	/* US Reset Transmitter */
#define AT91C_US_RXEN			((unsigned int) 0x1 <<  4)	/* US Receiver Enable */
#define AT91C_US_RXDIS			((unsigned int) 0x1 <<  5)	/* US Receiver Disable */
#define AT91C_US_TXEN			((unsigned int) 0x1 <<  6)	/* US Transmitter Enable */
#define AT91C_US_TXDIS			((unsigned int) 0x1 <<  7)	/* US Transmitter Disable */
#define AT91C_US_RSTSTA			((unsigned int) 0x1 <<  8)	/* US Reset Status Bits */

#define AT91C_US_USMODE_NORMAL	((unsigned int) 0x0)		/* USAR) Normal */
#define AT91C_US_USMODE_RS485	((unsigned int) 0x1)		/* USAR) RS485 */
#define AT91C_US_USMODE_HWHSH	((unsigned int) 0x2)		/* USAR) Hardware Handshaking */
#define AT91C_US_USMODE_MODEM	((unsigned int) 0x3)		/* USAR) Modem */
#define AT91C_US_USMODE_ISO7816_0	((unsigned int) 0x4)	/* USAR) ISO7816 protocol: T = 0 */
#define AT91C_US_USMODE_ISO7816_1	((unsigned int) 0x6)	/* USAR) ISO7816 protocol: T = 1 */
#define AT91C_US_USMODE_IRDA	((unsigned int) 0x8)		/* USAR) IrDA */
#define AT91C_US_USMODE_SWHSH	((unsigned int) 0xC)		/* USAR) Software Handshaking */

#define AT91C_US_CLKS_CLOCK		((unsigned int) 0x0 <<  4)	/* USAR) Clock */
#define AT91C_US_CLKS_FDIV1		((unsigned int) 0x1 <<  4)	/* USAR) fdiv1 */
#define AT91C_US_CLKS_SLOW		((unsigned int) 0x2 <<  4)	/* USAR) slow_clock (ARM) */
#define AT91C_US_CLKS_EXT		((unsigned int) 0x3 <<  4)	/* USAR) External (SCK) */

#define AT91C_US_CHRL_5_BITS	((unsigned int) 0x0 <<  6)	/* USAR) Character Length: 5 bits */
#define AT91C_US_CHRL_6_BITS	((unsigned int) 0x1 <<  6)	/* USAR) Character Length: 6 bits */
#define AT91C_US_CHRL_7_BITS	((unsigned int) 0x2 <<  6)	/* USAR) Character Length: 7 bits */
#define AT91C_US_CHRL_8_BITS	((unsigned int) 0x3 <<  6)	/* USAR) Character Length: 8 bits */

#define AT91C_US_PAR_EVEN		((unsigned int) 0x0 <<  9)	/* DBGU Even Parity */
#define AT91C_US_PAR_ODD		((unsigned int) 0x1 <<  9)	/* DBGU Odd Parity */
#define AT91C_US_PAR_SPACE		((unsigned int) 0x2 <<  9)	/* DBGU Parity forced to 0 (Space) */
#define AT91C_US_PAR_MARK		((unsigned int) 0x3 <<  9)	/* DBGU Parity forced to 1 (Mark) */
#define AT91C_US_PAR_NONE		((unsigned int) 0x4 <<  9)	/* DBGU No Parity */
#define AT91C_US_PAR_MULTI_DROP	((unsigned int) 0x6 <<  9)	/* DBGU Multi-drop mode */

#define AT91C_US_NBSTOP_1_BIT	((unsigned int) 0x0 << 12)	/* USART 1 stop bit */
#define AT91C_US_NBSTOP_15_BIT	((unsigned int) 0x1 << 12)	/* USART Asynchronous (SYNC=0) 2 stop bits Synchronous (SYNC=1) 2 stop bits */
#define AT91C_US_NBSTOP_2_BIT	((unsigned int) 0x2 << 12)	/* USART 2 stop bits */

#define BR    115200			/* Baud Rate */
#define BRD  (MCK/16/BR)		/* Baud Rate Divisor */

void rt_serial_init(void);

/**
 * @addtogroup AT91SAM7
 */
/*@{*/

/**
 * This function is used to display a string on console, normally, it's
 * invoked by rt_kprintf
 *
 * @param str the displayed string
 */
void rt_console_puts(const char* str)
{
	while (*str)
	{
		rt_serial_putc (*str++);
	}
}

/**
 * This function initializes serial
 */
void rt_serial_init()
{
	/* enable USART 0 */
	AT91C_PMC_PCER = 1 << AT91C_ID_US0;
	/* Enable RxD0 and TxDO Pin */
	AT91C_PIO_PDR = (1 << 5) | (1 << 6);

	AT91C_US0_CR = AT91C_US_RSTRX	|		/* Reset Receiver      */
				AT91C_US_RSTTX		|		/* Reset Transmitter   */
				AT91C_US_RXDIS		|		/* Receiver Disable    */
				AT91C_US_TXDIS;				/* Transmitter Disable */

	AT91C_US0_MR = AT91C_US_USMODE_NORMAL |		/* Normal Mode */
				AT91C_US_CLKS_CLOCK		|		/* Clock = MCK */
				AT91C_US_CHRL_8_BITS	|		/* 8-bit Data  */
				AT91C_US_PAR_NONE		|		/* No Parity   */
				AT91C_US_NBSTOP_1_BIT;			/* 1 Stop Bit  */

	/* set baud rate divisor */
	AT91C_US0_BRGR = BRD;

	AT91C_US0_CR = AT91C_US_RXEN |	/* Receiver Enable     */
				AT91C_US_TXEN;	/* Transmitter Enable  */
}

/**
 * This function read a character from serial without interrupt enable mode
 *
 * @return the read char
 */
char rt_serial_getc()
{
	/* Wait for Full Rx Buffer */
	while (!(AT91C_US0_CSR & AT91C_US_RXRDY));

	/* Read Character */
	return (AT91C_US0_RHR);
}

/**
 * This function will write a character to serial without interrupt enable mode
 *
 * @param c the char to write
 */
void rt_serial_putc(const char c)
{
	/*
		to be polite with serial console add a line feed
		to the carriage return character
	*/
	if (c=='\n')
	{
		while (!(AT91C_US0_CSR & AT91C_US_TXRDY));	
		AT91C_US0_THR = '\r';
	}

	/* Wait for Empty Tx Buffer */
	while (!(AT91C_US0_CSR & AT91C_US_TXRDY));

	/* Transmit Character */
	AT91C_US0_THR = c;
}

/*@}*/