[参考译文] TM4C129EKCPDT：I2C ACK/NACK 问题

您好！

 请在以下行的每个地方更改、

发件人：

while (MAP_I2CMasterBusy (I2C2_base))；

至：

while (！MAP_I2CMasterBusy (I2C2_base))// 在 while  (MAP_I2CMasterBusy (I2C2_base))的所有位置之前添加此行。

while (MAP_I2CMasterBusy (I2C2_base))；

您好、Archie。

 我不熟悉  TMP1075NDRLR 、但您读取的 I2C 波形是否符合  TMP1075NDRLR 数据表中显示的波形。

在您的代码中、我没有看到您从从从地址字节开始。 第一行从  将数据写入 TX 缓冲区的 MAP_I2CMasterDataPut (I2C2_base、0x00)开始。 它的作用是什么？ 您在哪里启动用于读取的从地址字节、如上面的时序图中所示？

下面是 I2C 器件的读数示例。  

void
I2CReadCommand(uint32_t * pui32DataRx)
{
    //
    // Modify the data direction to true, so that seeing the address will
    // indicate that the I2C Master is initiating a read from the slave.
    //
    MAP_I2CMasterSlaveAddrSet(I2C7_BASE, SHT21_I2C_ADDRESS, true);

    //
    // Setup for first read.  Use I2C_MASTER_CMD_BURST_RECEIVE_START
    // to start a burst mode read.  The I2C master continues to own
    // the bus at the end of this transaction.
    //
    MAP_I2CMasterControl(I2C7_BASE, I2C_MASTER_CMD_BURST_RECEIVE_START);

    //
    // Wait until master module is done transferring.
    // The I2C module has a delay in setting the Busy flag in the register so
    // there needs to be a delay before checking the Busy bit.  The below loops
    // wait until the Busy flag is set, and then wait until it is cleared to
    // indicate that the transaction is complete.  This can take up to 633 CPU
    // cycles @ 100 kbit I2C Baud Rate and 120 MHz System Clock.  Therefore, a
    // while loop is used instead of SysCtlDelay.
    //
    while(!MAP_I2CMasterBusy(I2C7_BASE))
    {
    }
    while(MAP_I2CMasterBusy(I2C7_BASE))
    {
    }

    //
    // Read the first byte data from the slave.
    //
    pui32DataRx[0] = MAP_I2CMasterDataGet(I2C7_BASE);

    //
    // Setup for the second read.  Use I2C_MASTER_CMD_BURST_RECEIVE_CONT
    // to continue the burst mode read.  The I2C master continues to own
    // the bus at the end of this transaction.
    //
    MAP_I2CMasterControl(I2C7_BASE, I2C_MASTER_CMD_BURST_RECEIVE_CONT);

    //
    // Wait until master module is done transferring.
    //
    while(!MAP_I2CMasterBusy(I2C7_BASE))
    {
    }
    while(MAP_I2CMasterBusy(I2C7_BASE))
    {
    }

    //
    // Read the second byte data from the slave.
    //
    pui32DataRx[1] = MAP_I2CMasterDataGet(I2C7_BASE);

    //
    // Setup for the third read.  Use I2C_MASTER_CMD_BURST_RECEIVE_FINISH
    // to terminate the I2C transaction.  At the end of this transaction,
    // the STOP bit will be issued and the I2C bus is returned to the
    // Idle state.
    //
    MAP_I2CMasterControl(I2C7_BASE, I2C_MASTER_CMD_BURST_RECEIVE_FINISH);

    //
    // Wait until master module is done transferring.
    //
    while(!MAP_I2CMasterBusy(I2C7_BASE))
    {
    }
    while(MAP_I2CMasterBusy(I2C7_BASE))
    {
    }
    
    //
    // Note the third 8-bit data is the checksum byte.  It will be
    // left to the users as an exercise if they want to verify if the
    // checksum is correct.
    pui32DataRx[2] = MAP_I2CMasterDataGet(I2C7_BASE);
}

我认为您的波形不符合 TMP1075数据表中指定的读取序列。 查看下面的波形、了解从传感器读取一个字节的数据。 为了进行读取、您需要提供第一个帧、其中是用于写入方向的从器件地址字节。 第二帧是指定要读取的寄存器。 在第三帧中、您需要再次为读取方向提供一个从器件地址字节。 第四个帧是传感器器件返回的数据。 在您的波形中、我没有看到前两个帧。 我只能看到您从第3帧开始、然后再进行三次读取。 您能展示前两帧吗？  

Archie、

 感谢您发送编修。 很高兴问题得到解决。