spi_drv.c

at89s52的spi程序,对单片机初学者有用处.

/*C**************************************************************************
* NAME:         spi_drv.c
*----------------------------------------------------------------------------
* Copyright (c) 2003 Atmel.
*----------------------------------------------------------------------------
* RELEASE:      cc03-demo-spi-0_0_1      
* REVISION:     1.1.1.1     
*----------------------------------------------------------------------------
* PURPOSE: 
* spi library low level functions (init, receive and send functions)                                               
* and global variables declarations to use with user software application
*****************************************************************************/



/*_____ I N C L U D E S ____________________________________________________*/
#include "config.h"
#include "spi_drv.h"

/*_____ M A C R O S ________________________________________________________*/

/*_____ D E F I N I T I O N ________________________________________________*/

/*_____ D E C L A R A T I O N ______________________________________________*/

// Here are some global flags to use with spi library
// These global flags arec used to communicate with higher level functions ( user application )
volatile bit b_spi_error;				// General pupose error flag
volatile bit b_spi_transmit_completed;	// for interrupt transmition use ( set when completed )
volatile bit b_spi_busy;				// set when spi interface is in use

// Here the globals variables to communicate with spi interrupt routine
volatile unsigned char *spi_string_ptr;	// pointer to data buffer
volatile unsigned char spi_nb_data;		// number of data



/*F**************************************************************************
* NAME: spi_master_init 
*----------------------------------------------------------------------------
* PARAMS:
* cpol: bit CPOL value
* cpha: bit CPHA value
* ssdis: bit SSDIS value
* speed: Uchar spi speed ratio transmission Vs Fper 
* return:   none
*----------------------------------------------------------------------------
* PURPOSE: 
* Initialize the spi module in master mode
*----------------------------------------------------------------------------
* EXAMPLE:
* spi_master_init(0,1,1,4); // init spi in mater mode with CPOL=0, CPHA=1, 
*                           // SSDIS=1 and bitrate=Fper/4 
*----------------------------------------------------------------------------
* NOTE:
*****************************************************************************/
void spi_master_init(bit cpol, bit cpha, bit ssdis,Uchar speed)
{
	b_spi_busy=0;
	b_spi_error=0;
	b_spi_transmit_completed=0;
	SPCON = 0;
	SPCON |= MSK_SPCON_MSTR;
	spi_set_speed(speed);
	if (cpol) SPCON |= MSK_SPCON_CPOL;
	if (cpha) SPCON |= MSK_SPCON_CPHA;
	if (ssdis) 	SPCON |= MSK_SPCON_SSDIS;
	SPCON |= MSK_SPCON_SPEN;
}

/*F**************************************************************************
* NAME: spi_slave_init 
*----------------------------------------------------------------------------
* PARAMS:
* cpol: bit CPOL value
* cpha: bit CPHA value
* ssdis: bit SSDIS value
* return:   none
*----------------------------------------------------------------------------
* PURPOSE: 
* Initialize the spi module in slave mode
*----------------------------------------------------------------------------
* EXAMPLE:
* spi_master_init(0,1,1); // init spi in mater mode with CPOL=0, CPHA=1, SSDIS=1
*----------------------------------------------------------------------------
* NOTE:
*****************************************************************************/
void spi_slave_init(bit cpol, bit cpha, bit ssdis)
{
	b_spi_busy=0;
	b_spi_error=0;
	b_spi_transmit_completed=0;
	SPCON = 0;
	if (cpol) SPCON |= MSK_SPCON_CPOL;
	if (cpha) SPCON |= MSK_SPCON_CPHA;
	if (ssdis) 	SPCON |= MSK_SPCON_SSDIS;
	SPCON |= MSK_SPCON_SPEN;
}

/*F**************************************************************************
* NAME: spi_transmit_byte
*----------------------------------------------------------------------------
* PARAMS:  tx_data: byte to send
* return:  byte received 
*----------------------------------------------------------------------------
* PURPOSE: 
* Send and receive a byte with spi interface 
*----------------------------------------------------------------------------
* NOTE: 
* If a current spi transfert is on going, the function performs an active wait polling on spi event.
* This function can be used both in slave and master mode
*****************************************************************************/
unsigned char spi_transmit_byte(unsigned char tx_data)
{
	unsigned char rx_data;

	if ( b_spi_busy )				// If current transfert is on going
	{
		while(!Spif_set()); 	//Wait end of current transfert
		rx_data=SPDAT;
	}
	SPDAT=tx_data;
	b_spi_busy=1;
	return	rx_data;
}


/*F**************************************************************************
* NAME: spi_get_data
*----------------------------------------------------------------------------
* PARAMS: none
* return: byte received 
*----------------------------------------------------------------------------
* PURPOSE: 
* Return the content of the spi data register 
*----------------------------------------------------------------------------
* NOTE: 
* This function performs an active wait polling
*****************************************************************************/
unsigned char spi_get_data()
{
	unsigned char to_return;
	while(!Spif_set()); //Wait end of current transfert
	to_return=SPDAT;		
	b_spi_busy=0;						// Release spi ressouce 
	return to_return;

}



/*F**************************************************************************
* NAME: spi_put_data
*----------------------------------------------------------------------------
* PARAMS: to_transmit: data to send
* return: none
*----------------------------------------------------------------------------
* PURPOSE:
* Send a data byte to the spi interface
*----------------------------------------------------------------------------
* NOTE: 
* This function should be use in spi slave mode to load spi data register
* with the next data to be transmited in slave mode
*****************************************************************************/
void spi_put_data( unsigned char to_transmit)
{
	SPDAT=to_transmit;

}



/*F**************************************************************************
* NAME: spi_transmit_burst_polling
*----------------------------------------------------------------------------
* PARAMS: *ptr_buf: data to send
* nb_data: number of data to send
* return: none 
*----------------------------------------------------------------------------
* PURPOSE:
* Transmit a data string throught the spi interface in polling mode 
*----------------------------------------------------------------------------
* NOTE: 
* This function performs an active wait polling
*****************************************************************************/
void spi_transmit_burst_polling( unsigned char  *ptr_buf, unsigned char nb_data)
{
unsigned char received;
  while (nb_data != 0)
  {

		while(Spte_set())     // Wait for transmit buffer free
		{
	   	SPDAT = *ptr_buf;	
 	   	received = SPDAT;
    	*ptr_buf = received;
    	ptr_buf++;
    	nb_data--;
		}
  }
}


/*F**************************************************************************
* NAME: spi_set_speed
*----------------------------------------------------------------------------
* PARAMS: ratio: spi clock ratio/XTAL  
* return: bit: status  
*----------------------------------------------------------------------------
* PURPOSE: 
* Configure the baud rate of the spi, set CR2, CR1, CR0
*----------------------------------------------------------------------------
* NOTE: 
* This function is use only in spi master mode
*****************************************************************************/
bit spi_set_speed (unsigned char ratio)
{
switch ( ratio )
	{
	case 2:
		SPCON |= SPI_RATIO_2;
		return	TRUE;
	break;

	case 4:
		SPCON |= SPI_RATIO_4;
		return	TRUE;
	break;

	case 8:
		SPCON |= SPI_RATIO_8;
		return	TRUE;
	break;

	case 16:
		SPCON |= SPI_RATIO_16;
		return	TRUE;
	break;

	case 32:
		SPCON |= SPI_RATIO_32;
		return	TRUE;
	break;

	case 64:
		SPCON |= SPI_RATIO_64;
		return	TRUE;
	break;

	case 128:
		SPCON |= SPI_RATIO_128;
		return	TRUE;
	break;

	default :
		return	FALSE;
	break;
	}
}

/*F**************************************************************************
* NAME: spi_transmit_burst_it
*----------------------------------------------------------------------------
* PARAMS:  
* *string_ptr: the string which must be send
* data_nb: number of data to send
* return: bit
*----------------------------------------------------------------------------
* PURPOSE: 
* Initialize an spi tranfert in interrupt mode
* Works in interrupt mode
* If a current transfert is on going, the function returns '0'
*----------------------------------------------------------------------------
* NOTE: 
* This function can be used in slave or master mode
*****************************************************************************/
bit spi_transmit_burst_it (Uchar *string_ptr, Uchar data_nb)
{
	if ( ~b_spi_busy )
	{
		b_spi_busy=1;
		b_spi_transmit_completed=0;
		b_spi_error=0;
		spi_string_ptr = string_ptr;
	  spi_nb_data = data_nb;
		SPDAT=*spi_string_ptr;
		return 1;
	}
	else	//current transfert on going
	{
		return 0;
	}
}


/*F**************************************************************************
* NAME: spi_interrupt
*----------------------------------------------------------------------------
* PARAMS:  
* *spi_string_ptr: the string which must be send
* spi_nb_data: number of data to send
* return: none
*----------------------------------------------------------------------------
* PURPOSE:
* spi - interruption program for serial transmission ( Master and Slave mode )
*----------------------------------------------------------------------------
* NOTE:
*****************************************************************************/
void spi_interrupt(void) interrupt IRQ_SPI
{
	if(Spif_set())
	{
		*spi_string_ptr=SPDAT;
		spi_nb_data--;
		if (spi_nb_data!=0)
		{
			spi_string_ptr++;
			SPDAT=*spi_string_ptr;
		}
		else
		{
			b_spi_busy=0;
			b_spi_transmit_completed=1;
		}
	}

}