// Copyright 2006 Yamane Akira
//ICC-AVR application builder : 2005/07/24 9:21:20
// Target : M48
// Crystal: 8.0000Mhz
// TWI Slave Mode Test Program
// Programmed by A.Yamane

#include <iom48v.h>
#include <macros.h>

 unsigned char s_addr, rdata;
 unsigned char tdata;
 const char CDATA[]={0x01,0x80,0x02,0x40,0x04,0x20,0x08,0x10};

void port_init(void)
{
 PORTB = 0x00;
 DDRB  = 0x00;
 PORTC = 0b1001111; //m103 output only
 DDRC  = 0x00;
 PORTD = 0xFF;
 DDRD  = 0xFF;
}

//TWI initialize
// bit rate:1
void twi_init(void)
{
 TWCR= 0X00; //disable twi
 TWBR= 0x01; //set bit rate
 TWSR= 0x00; //set prescale
 TWAR= 0x01; //set slave address
 TWCR= 0x04; //enable twi
}

//call this routine to initialize all peripherals
void init_devices(void)
{
 //stop errant interrupts until set up
 CLI(); //disable all interrupts
 port_init();
 twi_init();

 MCUCR = 0x00;
 EICRA = 0x00; //extended ext ints
 EIMSK = 0x00;
 
 TIMSK0 = 0x00; //timer 0 interrupt sources
 TIMSK1 = 0x00; //timer 1 interrupt sources
 TIMSK2 = 0x00; //timer 2 interrupt sources
 
 PCMSK0 = 0x00; //pin change mask 0 
 PCMSK1 = 0x00; //pin change mask 1 
 PCMSK2 = 0x00; //pin change mask 2
 PCICR = 0x00; //pin change enable 
 PRR = 0x00; //power controller
 SEI(); //re-enable interrupts
 //all peripherals are now initialized
}

void ERROR(unsigned char edata)
    {
	PORTD= ~edata;
    while(1);
	}
	
unsigned char SlaveReceive(void)
    {
	 TWCR = (1 << TWINT) | (1 << TWEN);
	 TWAMR = 0x00;
	 TWAR = ((s_addr <<1) | 0);
	 TWCR = (1 << TWEA) | (1 << TWEN);
	   while (!(TWCR & (1 << TWINT)))
	         ;		 
	  if ((TWSR & 0xF8) != 0x60)    
		  ERROR(3);
	 TWCR = (1 << TWINT) | (1 << TWEA) | (1 << TWEN);
	    while (!(TWCR & (1 << TWINT)))
		    ;
      if ((TWSR & 0xF8) != 0x080)
		  ERROR(4);	
    	 rdata = TWDR;	
	 TWCR = (1 << TWINT) | (1 << TWEN);
	    while (!(TWCR & (1 << TWINT)))
		    ;
		  if ((TWSR & 0xF8) != 0x0A0)
		    ERROR(5);
	 TWCR = (1 << TWINT) | (1 << TWEN);			
			 return rdata;		 
	}

void SlaveTransmit(void)
    {
	 TWCR = (1 << TWINT) | (1 << TWEN);
//	 TWAMR = 0xFE;
	 TWAR = ((s_addr <<1) | 0);
	 TWCR = (1 << TWEA) | (1 << TWEN);
	   while (!(TWCR & (1 << TWINT)))
	         ;		
	  if ((TWSR & 0xF8) != 0xA8)    
		  ERROR(0x30);
		TWDR = tdata; 
	 TWCR = (1 << TWINT) | (1 << TWEA) | (1 << TWEN);
	    while (!(TWCR & (1 << TWINT)))
		    ;
      if ((TWSR & 0xF8) != 0x0C0)
		  ERROR(0x40);		 
	}

//
void main(void)
{
 init_devices();
    s_addr = 0x50;   
    PORTD =0xAA;

    while(1)
	  {
	    rdata = SlaveReceive();
		tdata = CDATA[rdata];
	    SlaveTransmit();
		PORTD = ~rdata;
	  }
}