IIC主设备读操作问题

只看该作者 · 2013-2-2 12:34

static u8 I2C_MMA_ByteRead(u8 ReadAddr)
{
u8 RxData;
/*wait until I2C bus is not busy*/
while(I2C_GetFlagStatus(I2C1, I2C_FLAG_BUSY));

/* Send START condition */
I2C_GenerateSTART(I2C1, ENABLE);

/* Test on EV5 and clear it */
while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT));

/* Send MMA address for write */
I2C_Send7bitAddress(I2C1, MMA_ADRESS, I2C_Direction_Transmitter);

/* Test on EV6 and clear it */
while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED));

/* Clear EV6 by setting again the PE bit */
I2C_Cmd(I2C1, ENABLE);

/* Send the MMA's Register address to write to */
I2C_SendData(I2C1, ReadAddr);

/* Test on EV8 and clear it */
while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_TRANSMITTED));

/* Send STRAT condition a second time */
I2C_GenerateSTART(I2C1, ENABLE);

/* Test on EV5 and clear it */
while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT));

/* Send MMA address for read */
I2C_Send7bitAddress(I2C1, MMA_ADRESS, I2C_Direction_Receiver);

/* Test on EV6 and clear it */
while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_RECEIVER_MODE_SELECTED));

/* Test on wait for EV7 */
while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_RECEIVED));

/* Read a byte from the MMA Register */
RxData = I2C_ReceiveData(I2C1);

/* Disable Acknowledgement */
I2C_AcknowledgeConfig(I2C1, DISABLE);

/* Send STOP Condition */
I2C_GenerateSTOP(I2C1, ENABLE);

/*Retrun Data*/
return RxData;
}

1.
I2C_Cmd(I2C1, ENABLE);这一句有什么用？

2.
I2C_AcknowledgeConfig(I2C1, DISABLE);
I2C_GenerateSTOP(I2C1, ENABLE);
手册：只接收一个字节时，将在EV6 时进行关闭应答和停止条件生成操作。
这两句放在了最后面，有没有问题？