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不会的。我下了一个用GPIO模拟I2C协议的程序，是可以读的出来的。

我看了atmel的twi测试程序，发现TWI_SR寄存器的RXRDY始终是1。按理说应该

在读了TWI_RHR后清零的。

调了一个礼拜了，郁闷！

已经搞定了。

1：始终频率的问题，可以是400K、300K或200K，但是100K不行。

2：I2C读写的问题，更改后如下：

int AT91F_TWI_Write(const AT91PS_TWI pTwi ,int address, char *data2send, int size)
{
unsigned int status, nb_trial;

// 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 | AT91C_TWI_STOP;


nb_trial = 0;

status = pTwi->TWI_SR;
while (!( status & AT91C_TWI_TXCOMP) && (nb_trial < 10)) {

nb_trial++;

if (status & AT91C_TWI_ERROR) {
// Si Under run OR NACK Start again
pTwi->TWI_CR = (unsigned int) (AT91C_TWI_START | AT91C_TWI_STOP);

// Program temporizing period (300us)
}
}

// 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, nb_trial;

// 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 | AT91C_TWI_STOP;

nb_trial = 0;

status = pTwi->TWI_SR;

while (!(status & AT91C_TWI_TXCOMP) && (nb_trial < 10)) {
nb_trial++;
status = pTwi->TWI_SR;
}

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;
}

to cech

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