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 *         ATMEL Microcontroller Software Support  -  ROUSSET  -
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//------------------------------------------------------------------------------
/// \dir
/// !Purpose
/// 
/// Functions and definitions for using a TWI peripheral.
/// 
/// !Usage
/// 
/// -# Configure the TWI using TWI_Configure.
/// -# Send data to a slave through the TWI using TWI_Write.
/// -# Reads data from a slave using TWI_Read.
//------------------------------------------------------------------------------

#ifndef TWI_H
#define TWI_H

//------------------------------------------------------------------------------
//         Headers
//------------------------------------------------------------------------------

#include <board.h>

//------------------------------------------------------------------------------
//         Definitions
//------------------------------------------------------------------------------
/// \internal Calculates the value for the CHDIV and CLDIV field given the
/// desired operating frequency and the system master clock. This macro assumes
/// the CKDIV field value equals one.
#define TWI_CWGR_DIV(Fmck, Ftwi)    (((Fmck / Ftwi) - 3) / 2)

/// Calculates the value of the TWI_CWGR register of a twi peripheral given the
/// system frequency and the desired operating frequency (both in Hz).
#define TWI_CWGR(Fmck, Ftwi) \
    ((1 << 16) | (TWI_CWGR_DIV(Fmck, Ftwi) << 8) | TWI_CWGR_DIV(Fmck, Ftwi))

//------------------------------------------------------------------------------
//         Exported functions
//------------------------------------------------------------------------------
extern void TWI_Configure(AT91S_TWI *twi,
                                 unsigned int id,
                                 unsigned int cwgr);
extern unsigned char TWI_Write(AT91S_TWI *twi,
                                      void *buffer,
                                      unsigned int bufferSize,
                                      unsigned char address,
                                      unsigned int internalAddress,
                                      unsigned int internalAddressSize);
extern unsigned char TWI_Read(AT91S_TWI *twi,
                                     void *buffer,
                                     unsigned int bufferSize,
                                     unsigned char address,
                                     unsigned int internalAddress,
                                     unsigned int internalAddressSize);

#endif //#ifndef TWI_H

