uart.c

芯科rf资料

/*
** ============================================================================
**
** FILE
**  uart.c
**
** DESCRIPTION
**  Contains all uart and buffer handle  functions
**
** CREATED
**  Silicon Laboratories Hungary Ltd
**
** COPYRIGHT
**  Copyright 2008 Silicon Laboratories, Inc.  
**	http://www.silabs.com
**
** ============================================================================
*/


#include "S8051.h"
#include "uart.h"




/*------------------------------------------------------------------------*/
/*						GLOBAL variables								  */
/*------------------------------------------------------------------------*/
idata uint8 CircBuf[80];								//circular buffer length
idata uint8 i_ptr;							//circular buffer input pointer
idata uint8 o_ptr;							//circular buffer output pointer
idata uint8 BufChar;						//character counter 

extern xdata uint8 rs232_timer;				//timer variable
extern xdata uint8 uart_ch_sent;

/*------------------------------------------------------------------------*/
/*						LOCAL function prototypes						  */
/*------------------------------------------------------------------------*/


/*+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
  +
  + FUNCTION NAME:  void UartInit(void)
  +
  + DESCRIPTION:    initialize the UART peripheral
  +
  + INPUT:			None
  +
  + RETURN:         None
  +
  + NOTES:          None
  +
  +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
void UartInit(void)
{

	SCON0 = 0x10;                      // SCON0: 8-bit variable bit rate
                                       //        level of STOP bit is ignored
                                       //        RX enabled
                                       //        ninth bits are zeros
                                       //        clear RI0 and TI0 bits
   #if (SYSCLK/BAUDRATE/2/256 < 1) 
      TH1 = -(SYSCLK/BAUDRATE/2);
      CKCON &= ~0x0B;                  // T1M = 1; SCA1:0 = xx
      CKCON |=  0x08;
   #elif (SYSCLK/BAUDRATE/2/256 < 4) 
      TH1 = -(SYSCLK/BAUDRATE/2/4);
      CKCON &= ~0x0B;                  // T1M = 0; SCA1:0 = 01
      CKCON |=  0x01;
   #elif (SYSCLK/BAUDRATE/2/256 < 12) 
      TH1 = -(SYSCLK/BAUDRATE/2/12);
      CKCON &= ~0x0B;                  // T1M = 0; SCA1:0 = 00
   #else 
      TH1 = -(SYSCLK/BAUDRATE/2/48);
      CKCON &= ~0x0B;                  // T1M = 0; SCA1:0 = 10
      CKCON |=  0x02;
   #endif

   TL1 = TH1;                          // init Timer1
   TMOD &= ~0xf0;                      // TMOD: timer 1 in 8-bit autoreload
   TMOD |=  0x20;
   TR1 = 1;                            // START Timer1
   TI0 = 1;                            // Indicate TX0 ready
   ES0 = 1;                            // Enable UART0 interrupts
}


/*+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
  +
  + FUNCTION NAME:  void putch(char ch)
  +
  + DESCRIPTION:    print one character to Uart
  +
  + INPUT:			ch - a character 
  +
  + RETURN:         None
  +
  + NOTES:          None
  +
  +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/

char putchar(char ch)
{
	
	
	SBUF0 = ch;
	while( uart_ch_sent == 0);
	uart_ch_sent = 0;
	
	return 0;
}


/*+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
  +
  + FUNCTION NAME:  void UartRxISR(void)
  +
  + DESCRIPTION:    UART Receive interrupt handler
  +
  + INPUT:			None
  +
  + RETURN:         None
  +
  + NOTES:          UartInit() has to be call before
  +
  +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/

void UartRxISR(void)
{
	
	CircBuf[i_ptr] = SBUF0;										// get new character
	
	if(++i_ptr == CIRC_BUF_LEN) i_ptr = 0;						// buffer is circular
	if(i_ptr == o_ptr) 											// is the buffer full?
	{
		if(++o_ptr == CIRC_BUF_LEN) o_ptr = 0;					// if yes, inc output pointer
	}
	else BufChar++;
    rs232_timer = 1;                                            // restart rs232 rx timer                                         				
}

/*+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
  +
  + FUNCTION NAME:  char ReadBuffer(void)
  +
  + DESCRIPTION:    Read one byte from the circulat buffer
  +
  + INPUT: 			None
  +
  + RETURN:         the next character from the circular buffer
  +
  + NOTES:          None
  +
  +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/

char ReadBuffer(void)
{

	idata uint8 nextChar;

	if (BufChar)
	{
		BufChar--;												// decrement the buffer
		nextChar = CircBuf[o_ptr];								// get the last character	
		if(++o_ptr == CIRC_BUF_LEN) o_ptr = 0;	                // step to the next one 		
	return nextChar;
	}
}