software_spi.c

Software spi header file using 3 general purpose IO pins of an atmel uc

#include <avr/io.h>
#include <avr/interrupt.h>

#define clearbit(sfr,bit) (_SFR_BYTE (sfr) &= ~_BV(bit))
#define setbit(sfr,bit) (_SFR_BYTE (sfr) |= _BV(bit))


#define S_MOSI		PORTB4
#define S_MISO		PORTB3
#define S_SCK		PORTB2
#define SPI_PORT	PORTB
#define SPI_IN		PINB
#define SPI_DIR		DDRB
#define CS_PORT		PORTB
#define CS			PORTB1

#define CS_ON		clearbit(CS_PORT,CS)		
#define CS_OFF		setbit(CS_PORT,CS)
#define S_MOSI_1	setbit(SPI_PORT,S_MOSI)
#define S_MOSI_0	clearbit(SPI_PORT,S_MOSI)
#define S_SCK_1		setbit(SPI_PORT,S_SCK)
#define S_SCK_0		clearbit(SPI_PORT,S_SCK)

unsigned char data2;

void port_init(void)
 {
 SPI_DIR |= ( 1 << CS) | ( 1 << S_MOSI ) | ( 1 << S_SCK );
 }

void Software_SPI_Write(unsigned char data)		// J