麻烦大家帮忙看看，我使用TI TM4C123系列产品，SPI程序如下：
void SPIInit(uint32_t ui32Base, uint32_t ui32Clock, uint32_t ui32BitRate)
{
    SPIGPIOInit();
    //
    // Configure the SPI module.
    //
    MAP_SSIConfigSetExpClk(SSI3_BASE, ROM_SysCtlClockGet(), SSI_FRF_MOTO_MODE_0,
                           SSI_MODE_MASTER,1000000, 8);

    //
    // Enable the advanced mode of operation, defaulting to read/write mode.
    //
    MAP_SSIAdvModeSet(SSI3_BASE, SSI_ADV_MODE_READ_WRITE);

    //
    // Enable the frame hold feature.
    //
    MAP_SSIAdvFrameHoldEnable(SSI3_BASE);

    //
    // Enable the SPI module.
    //
    MAP_SSIEnable(SSI3_BASE);
}

void SPIRead(uint32_t ui32Addr, uint8_t *pui8Data,
             uint32_t ui32Count)
{
    uint32_t ui32Trash;

    //
    // Drain any residual data from the receive FIFO.
    //
    while(MAP_SSIDataGetNonBlocking(SSI3_BASE, &ui32Trash) != 0)
    {
    }

    //
    // Set the SSI module into write-only mode.
    //
    MAP_SSIAdvModeSet(SSI3_BASE, SSI_ADV_MODE_WRITE);

    //
    // Send the read command.
    //
    MAP_SSIDataPut(SSI3_BASE, CMD_READ);

    //
    // Send the address of the first byte to read.
    //
    MAP_SSIDataPut(SSI3_BASE, (ui32Addr >> 8) & 0xff);
    MAP_SSIDataPut(SSI3_BASE, ui32Addr & 0xff);

    //
    // Set the SSI module into read/write mode.  In this mode, dummy writes are
    // required in order to make the transfer occur; the SPI flash will ignore
    // the data.
    //
    MAP_SSIAdvModeSet(SSI3_BASE, SSI_ADV_MODE_READ_WRITE);

    //
    // See if there is a single byte to be read.
    //
    if(ui32Count == 1)
    {
        //
        // Perform a single dummy write, marking it as the end of the frame.
        //
        MAP_SSIAdvDataPutFrameEnd(SSI3_BASE, 0);
    }
    else
    {
        //
        // Perform a dummy write to prime the loop.
        //
        MAP_SSIDataPut(SSI3_BASE, 0);

        //
        // Loop while there is more than one byte left to be read.
        //
        while(--ui32Count != 1)
        {
            //
            // Perform a dummy write to keep the transmit FIFO from going
            // empty.
            //
            MAP_SSIDataPut(SSI3_BASE, 0);

            //
            // Read the next data byte from the receive FIFO and place it into
            // the data buffer.
            //
            MAP_SSIDataGet(SSI3_BASE, &ui32Addr);
            *pui8Data++ = ui32Addr & 0xff;
        }

        //
        // Perform the final dummy write, marking it as the end of the frame.
        //
        MAP_SSIAdvDataPutFrameEnd(SSI3_BASE, 0);

        //
        // Read the next data byte from the receive FIFO and place it into the
        // data buffer.
        //
        MAP_SSIDataGet(SSI3_BASE, &ui32Addr);
        *pui8Data++ = ui32Addr & 0xff;
    }

    //
    // Read the final data byte from the receive FIFO and place it into the
    // data buffer.
    //
    MAP_SSIDataGet(SSI3_BASE, &ui32Addr);
    *pui8Data++ = ui32Addr & 0xff;
}
用示波器测试信号，写，时钟和片选信号均正常，EEPROM的输出无信号，一直为0.我使用的EEPROM型号
是25LC512.
麻烦各位大侠了！

此帖出自小平头技术问答