twi.c

YL9200开发板的测试代码,详细请下载后细看

//*--------------------------------------------------------------------------------------
//* 	 ATMEL Microcontroller Software Support  -  ROUSSET  -
//*--------------------------------------------------------------------------------------
//* The software is delivered "AS IS" without warranty or condition of any
//* kind, either express, implied or statutory. This includes without
//* limitation any warranty or condition with respect to merchantability or
//* fitness for any particular purpose, or against the infringements of
//* intellectual property rights of others.
//*--------------------------------------------------------------------------------------
//* File Name   		: twi.c
//* Object  			: Basic TWI EEPROM driver
//* Translator  		:
//* 1.0 25/11/02 NL		: Creation
//*--------------------------------------------------------------------------------------
#include "AT91RM9200.h"
#include "def.h"
#include "config.h"
#include "twi.h"

#ifdef	IIC_SUPPORT
//*----------------------------------------------------------------------------
//* \fn    AT91F_SetTwiClock
//* \brief Initialization
//*----------------------------------------------------------------------------
void AT91F_SetTwiClock( const AT91PS_TWI pTwi )
{
	int sclock;

	/* Here, CKDIV = 1 and CHDIV=CLDIV  ==> CLDIV = CHDIV = 1/4*((Fmclk/FTWI) -6)*/

	sclock = ( 10 * AT91C_MASTER_CLOCK / AT91C_TWI_CLOCK );
	if ( sclock % 10 >= 5 )
		sclock = ( sclock / 10 ) - 5;
	else
		sclock = ( sclock / 10 ) - 6;
	sclock = ( sclock + ( 4 - sclock % 4 ) ) >> 2;	// div 4

	pTwi->TWI_CWGR = 0x00010000 | sclock | ( sclock << 8 );
}

//*=========================================================
//*		WRITE
//*=========================================================
//*----------------------------------------------------------------------------
//* \fn    AT91F_TWI_Write
//* \brief Send n bytes to a slave device
//*----------------------------------------------------------------------------
int AT91F_TWI_Write( const AT91PS_TWI pTwi , int address , char* data2send , int size )
{
	unsigned int status;

	// Set the TWI Master Mode Register
	pTwi->TWI_MMR = ( AT91C_EEPROM_I2C_ADDRESS | AT91C_TWI_IADRSZ_2_BYTE ) & ~AT91C_TWI_MREAD;	

	// Set TWI Internal Address Register
	pTwi->TWI_IADR = address;

	status = pTwi->TWI_SR;

	pTwi->TWI_THR = *( data2send++ );

	pTwi->TWI_CR = AT91C_TWI_START;

	while ( size-- > 1 )
	{
		// Wait THR Holding register to be empty
		while ( !( pTwi->TWI_SR & AT91C_TWI_TXRDY ) );

		// Send first byte
		pTwi->TWI_THR = *( data2send++ );
	}

	pTwi->TWI_CR = AT91C_TWI_STOP;		

	status = pTwi->TWI_SR;

	// Wait transfer is finished
	while ( !( pTwi->TWI_SR & AT91C_TWI_TXCOMP ) );

	return AT91C_EEPROM_WRITE_OK;
}

//*=========================================================
//*		READ
//*=========================================================
//*----------------------------------------------------------------------------
//* \fn    AT91F_TWI_Read
//* \brief Read n bytes from a slave device
//*----------------------------------------------------------------------------
int AT91F_TWI_Read( const AT91PS_TWI pTwi , int address , char* data , int size )
{
	unsigned int status;

	// Set the TWI Master Mode Register
	pTwi->TWI_MMR = AT91C_EEPROM_I2C_ADDRESS | AT91C_TWI_IADRSZ_2_BYTE | AT91C_TWI_MREAD;	

	// Set TWI Internal Address Register
	pTwi->TWI_IADR = address;

	// Start transfer
	pTwi->TWI_CR = AT91C_TWI_START;

	status = pTwi->TWI_SR;

	while ( size-- > 1 )
	{
		// Wait RHR Holding register is full
		while ( !( pTwi->TWI_SR & AT91C_TWI_RXRDY ) );

		// Read byte
		*( data++ ) = pTwi->TWI_RHR;
	}

	pTwi->TWI_CR = AT91C_TWI_STOP;

	status = pTwi->TWI_SR;

	// Wait transfer is finished
	while ( !( pTwi->TWI_SR & AT91C_TWI_TXCOMP ) );

	// Read last byte
	*data = pTwi->TWI_RHR;

	return AT91C_EEPROM_READ_OK;
}

#endif	/* IIC_SUPPORT */