/*****************************************************************************
*
* Atmel Corporation
*
* File              : main.c
* Compiler          : IAR EWAAVR 2.28a/3.10c
* Revision          : $Revision: 1.1 $
* Date              : $Date: Friday, October 15, 2004 11:06:56 UTC $
* Updated by        : $Author: ltwa $
*
* Support mail      : avr@atmel.com
*
* Supported devices : All devices with a TWI module the has a slave address mask
*                     register. The example is written for the ATmega48.
*
* AppNote           : AVR311 - TWI Slave Implementation
*
* Description       : Example of how to use the driver for TWI slave 
*                     communication. This version utilises the address mask register
*                     to enable response on several TWI slave addresses.
*
****************************************************************************/

#include <ioavr.h>
#include <inavr.h>
#include "TWI_Slave.h"

// Sample TWI transmission commands
#define TWI_CMD_MASTER_WRITE 0x10
#define TWI_CMD_MASTER_READ  0x20

unsigned char TWI_Act_On_Failure_In_Last_Transmission ( unsigned char TWIerrorMsg )
{
                    // A failure has occurred, use TWIerrorMsg to determine the nature of the failure
                    // and take appropriate actions.
                    // Se header file for a list of possible failures messages.
  
                    // This very simple example puts the error code on PORTB and restarts the transceiver with
                    // all the same data in the transmission buffers.
  PORTB = TWIerrorMsg;
  TWI_Start_Transceiver();
                    
  return TWIerrorMsg; 
}

void main( void )
{
  unsigned char messageBuf[4];
  unsigned char TWI_slaveAddress, TWI_slaveAddress2, TWI_slaveAddressMask, temp;

  // LED feedback port - connect port B to the STK500 LEDS
  DDRB  = 0xFF; // Set to ouput
  PORTB = 0x55; // Startup pattern

  // Own TWI slave address
  TWI_slaveAddress     = (0x10<<TWI_ADR_BITS);
  TWI_slaveAddress2    = (0x11<<TWI_ADR_BITS);                  // Alternativ slave address to respond to.
  TWI_slaveAddressMask = TWI_slaveAddress ^ TWI_slaveAddress2;  // XOR the addresses to get the address mask.

  // Initialise TWI module for slave operation. Include address and/or enable General Call.
  TWI_Slave_Initialise( TWI_slaveAddress | (TRUE<<TWI_GEN_BIT), TWI_slaveAddressMask); 
                                                                                  
  __enable_interrupt();

  // Start the TWI transceiver to enable reseption of the first command from the TWI Master.
  TWI_Start_Transceiver();

  // This example is made to work together with the AVR315 TWI Master application note. In adition to connecting the TWI
  // pins, also connect PORTB to the LEDS. The code reads a message as a TWI slave and acts according to if it is a 
  // general call, or an address call. If it is an address call, then the first byte is considered a command byte and
  // it then responds differently according to the commands.

  // This loop runs forever. If the TWI is busy the execution will just continue doing other operations.
  for(;;)
  {    
    // Check if the TWI Transceiver has completed an operation.
    if ( ! TWI_Transceiver_Busy() )                              
    {
    // Check if the last operation was successful
      if ( TWI_statusReg.lastTransOK )
      {
    // Check if the last operation was a reception
        if ( TWI_statusReg.RxDataInBuf )
        {
          TWI_Get_Data_From_Transceiver(messageBuf, 3);         
    // Check if the last operation was a reception as General Call        
          if ( TWI_statusReg.genAddressCall )
          {
          // Put data received out to PORTB as an example.        
            PORTB = messageBuf[1];                              
          }
    // Ends up here if the last operation was a reception as Slave Address Match                  
          else
          {
    // Take action dependant on what slave address that was used in the message
            if (messageBuf[0] == TWI_slaveAddress)
            {
    // Example of how to interpret a command and respond.            
            // TWI_CMD_MASTER_WRITE stores the data to PORTB
              if (messageBuf[1] == TWI_CMD_MASTER_WRITE)
                PORTB = messageBuf[2];                            
            // TWI_CMD_MASTER_READ prepares the data from PINB in the transceiver buffer for the TWI master to fetch.
              if (messageBuf[1] == TWI_CMD_MASTER_READ)
              {
                messageBuf[0] = PINB;                             
                TWI_Start_Transceiver_With_Data( messageBuf, 1 );           
              }
            }
            else
            {
              PORTB = messageBuf[1];  // Put TWI address data on PORTB
            }
          }
        }
    // Ends up here if the last operation was a transmission                  
        else
        {
            __no_operation(); // Put own code here.
        }
    // Check if the TWI Transceiver has already been started.
    // If not then restart it to prepare it for new receptions.             
        if ( ! TWI_Transceiver_Busy() )
        {
          TWI_Start_Transceiver();
        }      
      }
    // Ends up here if the last operation completed unsuccessfully
      else
      {
        TWI_Act_On_Failure_In_Last_Transmission( TWI_Get_State_Info() );
      }
      
    }
    // Do something else while waiting for the TWI transceiver to complete.    
    __no_operation(); // Put own code here.
  }
}


/*  
  // A simplified example.
  // This will store data received on PORTB, and increment it before sending it back.

  TWI_Start_Transceiver( );    
         
  for(;;)
  {
    if ( ! TWI_Transceiver_Busy() )                              
    {
      if ( TWI_statusReg.RxDataInBuf )
      {
        TWI_Get_Data_From_Transceiver(&temp, 1);  
        PORTB = temp;
      }
      temp = PORTB + 1;
      TWI_Start_Transceiver_With_Data(&temp, 1); 
    }
    __no_operation();   // Do something else while waiting
  }
}

*/