SPI interface programs for 8051 core microcontroller

HEADER FILE
#ifndef SPI_H
#define SPI_H

#include <8052.h>


#define SPI_SS         P2_7
#define SPI_READ    0x03
#define SPI_WRITE    0x02
#define SPI_WRDI    0x04
#define SPI_WREN    0x06
#define SPI_RDSR    0x05


/* SPI Special Function Registers */

__sfr __at(0XD5) SPCR;
__sfr __at(0XAA) SPSR;
__sfr __at(0X86) SPDAT;

void spi_init();
char spi_tx_rx(char val);
void spi_write_enable();
void spi_write(char val, char addr);
char spi_read(char addr);

#endif


LIBRARY FILE



#include <8052.h>
#include "spi.h"
#include "string.h"

#define SPI_SS P2_7

void spi_init()
{
    SPI_SS = 1;
    SPSR = 0;
    SPCR = 0x5c;
}

char spi_tx_rx(char val)
{
    SPDAT = val;        /* send data out spi port */
    while (!(SPSR & 0x80));    /* wait for transfer to complete */
    SPSR = 0;
    return SPDAT;
}

void spi_write_enable()
{
    SPI_SS = 0;
    spi_tx_rx(SPI_WREN);
    SPI_SS = 1;
    delay(10);
}

void spi_write(char val, char addr)
{
    spi_write_enable();
    SPI_SS = 0;
    spi_tx_rx(SPI_WRITE);
    spi_tx_rx(addr);
    spi_tx_rx(val);
    SPI_SS = 1;
    delay(10);
}

char spi_read(char addr)
{
    char ret;
    SPI_SS = 0;
    spi_tx_rx(SPI_READ);
    spi_tx_rx(addr);
    ret = spi_tx_rx(0);
    SPI_SS = 1;
    return ret;

}