/*****************************************************************************
*
* Atmel Corporation
*
* File              : main.c
* Compiler          : AVRGCC Toolchain version 3.4.2
* Revision          : $Revision: 992 $
* Date              : $Date: 2013-11-07 $
* Updated by        : $Author: Atmel $
*
* Support mail      : avr@atmel.com
*
* Supported devices : All device with USI module can be used.
*                     The example is written for the ATmega169, ATtiny26 & ATtiny2313
*
* AppNote           : AVR310 - Using the USI module as a TWI Master
*
* Description       : Example of how to use the driver for TWI master 
*                     communication with the USI module.
*                     This code reads PORTD and sends the status to the TWI slave.
*                     Then it reads data from the slave and puts the data on PORTB.
*                     To run the example use STK500 and connect PORTB to the LEDS,
*                     and PORTD to the switches.
*
****************************************************************************/
#include <avr/io.h>
#include <avr/interrupt.h>
#include "USI_TWI_Master.h"

#define SLAVE_ADDR  0x10

#define MESSAGEBUF_SIZE       4

#define TWI_GEN_CALL         0x00  // The General Call address is 0

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

// Sample TWI transmission states, used in the main application.
#define SEND_DATA             0x01
#define REQUEST_DATA          0x02
#define READ_DATA_FROM_BUFFER 0x03

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.
	 asm("nop");
	 return TWIerrorMsg;
}

int main( void )
{
  unsigned char messageBuf[MESSAGEBUF_SIZE];
  unsigned char TWI_targetSlaveAddress, temp, pressedButton, myCounter=0;

  //LED feedback port - connect port B to the STK500 LEDS
  DDRB  = 0xFF;
  PORTB = myCounter;
  
  //Switch port - connect portD to the STK500 switches
  DDRD  = 0x00;

  USI_TWI_Master_Initialise();
  
 sei();
  
  TWI_targetSlaveAddress   = 0x10;

  // This example is made to work together with the AVR311 TWI Slave application note and stk500.
  // In adition to connecting the TWI pins, also connect PORTB to the LEDS and PORTD to the switches.
  // The code reads the pins to trigger the action you request. There is an example sending a general call,
  // address call with Master Read and Master Write. The first byte in the transmission is used to send
  // commands to the TWI slave.

  // This is a stk500 demo example. The buttons on PORTD are used to control different TWI operations.
  for(;;)
  {  
    pressedButton = ~PIND;
    if (pressedButton)       // Check if any button is pressed
    {
      do{temp = ~PIND;}      // Wait until key released
      while (temp);
      
      temp = TRUE;  // I.e. Success. Used to trap failed operations.
      
      switch ( pressedButton ) 
      {
        // Send a Generall Call
        case (1<<PD0):      
          messageBuf[0] = TWI_GEN_CALL;     // The first byte must always consit of General Call code or the TWI slave address.
          messageBuf[1] = 0xAA;             // The command or data to be included in the general call.
          temp = USI_TWI_Start_Transceiver_With_Data( messageBuf, 2 );
          break;

        // Send a Address Call, sending a command and data to the Slave          
        case (1<<PD1):      
          messageBuf[0] = (TWI_targetSlaveAddress<<TWI_ADR_BITS) | (FALSE<<TWI_READ_BIT); // The first byte must always consit of General Call code or the TWI slave address.
          messageBuf[1] = TWI_CMD_MASTER_WRITE;             // The first byte is used for commands.
          messageBuf[2] = myCounter;                        // The second byte is used for the data.
          temp = USI_TWI_Start_Transceiver_With_Data( messageBuf, 3 );
          break;

        // Send a Address Call, sending a request, followed by a resceive          
        case (1<<PD2):      
          // Send the request-for-data command to the Slave
          messageBuf[0] = (TWI_targetSlaveAddress<<TWI_ADR_BITS) | (FALSE<<TWI_READ_BIT); // The first byte must always consit of General Call code or the TWI slave address.
          messageBuf[1] = TWI_CMD_MASTER_READ;             // The first byte is used for commands.
          temp = USI_TWI_Start_Transceiver_With_Data( messageBuf, 2 );

          // One might need to delay before proceding to enable the slave to interpret the last message,
          // and prepare the next request. Or as in this simple sample rerun the request until he responds. 

          // Transmit request and get the received data from the transceiver buffer
          messageBuf[0] = (TWI_targetSlaveAddress<<TWI_ADR_BITS) | (TRUE<<TWI_READ_BIT); // The first byte must always consit of General Call code or the TWI slave address.
          do
            temp = USI_TWI_Start_Transceiver_With_Data( messageBuf, 2 );
          while (USI_TWI_Get_State_Info() == USI_TWI_NO_ACK_ON_ADDRESS);
                 
          PORTB = messageBuf[1];        // Store data on PORTB.
          break;

        case (1<<PD3):      
          // Send the request-for-data command to the Slave
          if (TWI_targetSlaveAddress == 0x10)
           TWI_targetSlaveAddress = 0x15;
          else
           TWI_targetSlaveAddress = 0x10;
          break;
                              
        // Get status from Transceiver and put it on PORTB
        case (1<<PD5):
          PORTB = USI_TWI_Get_State_Info();
          break;

        // Increment myCounter and put it on PORTB          
        case (1<<PD6):      
          PORTB = ++myCounter;        
          break;
          
        // Reset myCounter and put it on PORTB
        case (1<<PD7):      
          PORTB = myCounter = 0;        
          break;  
      }
      
      if (!temp)    // One of the operations failed.
      {             // Use TWI status information to detemine cause of failure and take appropriate actions. 
        TWI_Act_On_Failure_In_Last_Transmission( USI_TWI_Get_State_Info( ) );  
       asm("nop"); // Put own code here.
      }
    }    
  }
}