SPI comm problem

Development Boards MicroMod
1

Hi there,

I am trying to learn SPI method of communication. I hooked up two STK500 board according to AVR151 application note, page 10(see link below)exactly. Except that in my case, I use ATmega16 and not Atmega162. I could not figure out what is the problem. Please have a look at it.

http://www.atmel.com/dyn/resources/prod … oc2585.pdf

Master

#include <avr/io.h>
//#include <stdio.h>
#include<avr/delay.h>

#define DD_MOSI 0x20  //PINB5
#define DD_SCK 0x80   //PINB7
#define DDR_SPI DDRB  //PORTB

#define sw0 0x01
#define sw1 0x02
#define sw2 0x04
#define sw3 0x08
#define sw4 0x10
#define sw5 0x20
#define sw6 0x40
#define sw7 0x80

void SPI_MasterInit(void)
{
	/* Set MOSI and SCK output, all others input */
	DDR_SPI = (1<<DD_MOSI)|(1<<DD_SCK);
	/* Enable SPI, Master, set clock rate fck/16 */
	SPCR = (1<<SPE)|(1<<MSTR)|(1<<SPR0);
}

void SPI_MasterTransmit(char cData)
{
	/* Start transmission */
	SPDR = cData;
	/* Wait for transmission complete */
	while(!(SPSR & (1<<SPIF)));
}




//int main()
void main(void)
{

	SPI_MasterInit();
	DDRA = 0x00;	//input
	DDRD = 0xFF;	//output
	PORTD = 0xff;	//turn off all LEDs
	
	while(1)
	{
		
		if( ( (PINA &sw0) == 0x00))	//if switch 0 is pressed
		{
			PORTD = 0xfe;
			SPI_MasterTransmit('0');
		}
		else if ( ( (PINA &sw1) == 0x00))
		{
			PORTD = 0xfd;
		}
		else if ( ( (PINA &sw2) == 0x00))
		{
			PORTD = 0xfb;
		}
		else if ( ( (PINA &sw3) == 0x00))
		{
			PORTD = 0xf7;
		}
		else if ( ( (PINA &sw4) == 0x00))
		{
			PORTD = 0xef;
		}
		else if ( ( (PINA &sw5) == 0x00))
		{
			PORTD = 0xdf;
		}
		else if ( ( (PINA &sw6) == 0x00))
		{
			PORTD = 0xbf;
		}
		else if ( ( (PINA &sw7) == 0x00))
		{
			PORTD = 0x7f;
		}
		
		
	}
	
		
	
}

Slave:

#include <avr/io.h>
//#include <stdio.h>
#include<avr/delay.h>


//#define DD_MISO 0x40  //PINB6
//#define DD_SCK 0x80 //PINB7
//#define DDR_SPI DDRB  //PORTB


#define DD_MISO PINB6
//#define DD_SCK PINB7
#define DDR_SPI PORTB

void SPI_SlaveInit(void)
{
	/* Set MISO output, all others input */
	DDR_SPI = (1<<DD_MISO);
	/* Enable SPI */
	SPCR = (1<<SPE);
}

char SPI_SlaveReceive(void)
{
	/* Wait for reception complete */
	while(!(SPSR & (1<<SPIF)));
	/* Return data register */
	return SPDR;
}


int main()
{
	SPI_SlaveInit();
	char selection;
	DDRD = 0xFF;	//output
	PORTD = 0xff;	//turn off all LEDs
	//SPI_SlaveReceive();
	while(1)
	{
		
		selection =	SPI_SlaveReceive();
		if( selection == '0')
		{
			PORTD = 0xfe;
		}
		
	
		
	}
}