twi.c

来自「基于AT91RM9200为核心的ARM开发板的RTC8025计时器的驱动程序 」· C语言 代码 · 共 105 行

//*--------------------------------------------------------------------------------------
//*      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 "main.h"
#include "twi.h"


//*=========================================================
//*		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_1_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_1_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;
}