// Copyright 2006 Yamane Akira
//ICC-AVR application builder : 2005/07/23 23:05
// Target : M8
// Crystal: 4.0000Mhz
// TWI MASTER Test Program

#include <iom8v.h>
#include <macros.h>

 unsigned char s_addr, status_b;

void port_init(void)
{
 PORTB = 0x00;
 DDRB  = 0x00;
 PORTC = 0x00; 
 DDRC  = 0x00;
 PORTD = 0xFF;
 DDRD  = 0xFF;
}

//TWI initialize
// bit rate:12
void twi_init(void)
{
 TWCR= 0X00; //disable twi
 TWBR= 0x0C; //set bit rate 12
 TWSR= 0x00; //set prescale 1x
 TWAR= 0x00; //set slave address
 TWCR= 0x04; //enable twi
}

void ERROR (unsigned char edata)
 {
  PORTD = ~edata; //display error#
  	  while(1);
 }

void MasterTransmit(unsigned char tdata)
  {
   TWCR = (1 << TWINT)|(1 << TWSTA)|(1 << TWEN); // send START condition
     while (!(TWCR & (1 << TWINT)))   // Confirm START has been transmitted
	         ;  
	   if ((TWSR &  0xF8) != 0x08)   // Check TWI Status register
	       ;
   TWDR = (s_addr <<1) | 0;   // Load SLA_W into TWDR
   TWCR = (1 << TWINT) | (1<<TWEN);
	  while (!(TWCR & (1 << TWINT))) // ACK has received
	         ;
	  if  ((TWSR & 0xF8) != 0x18)    // check MT_SLA_ACK
	      {
		   ERROR(2);
		  }
   TWDR = tdata;
   TWCR = (1 << TWINT) | (1 << TWEN);  
	    while (!(TWCR & (1 << TWINT)))
	          ;		
       if ((TWSR & 0xF8) != 0x28)  // check MT_DATA_ACK
           {
		    ERROR(4);
		   }
   TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO); // transmit STOP cond.  
  }

void delay(void)
  {
  unsigned char a,b;
   for (a=1; a; a++)
       for (b=1; b; b++)
	   ;
  }

  
//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;
 GICR  = 0x00;
 TIMSK = 0x00; //timer interrupt sources
 SEI(); //re-enable interrupts
 //all peripherals are now initialized
}

//
void main(void)
{
  	   unsigned char i;
 init_devices();
    s_addr = 0x10;
	PORTD = 0xFF;
     while(1)
     {
	  for (i=1; i < 0xFF; i++)
	   {
	   MasterTransmit(i);
	   PORTD = ~i;
	     delay();
	   } 
	 } 
}