LPC55S06 SPI write works, read no!

[MarcoGiammarini]

Hi,

I am using LPC55S06 to communicate with another microcontroller by using SPI. My microcontroller is the master, the other one is the slave. The configuration is CPOL=0 and CPHA=0, and the datarate is 500kbps. The protocol is 2 byte of register address (with 1 bit that indicate read/write) and 4 byte of data.

When I write a register no problem on my way: the data sniffed with a logic analyzer is perfect, and the slave read data well. When I try to read a register, the slave send out the data, on the logic analyzer the data is perfect, but on microcontroller the last bit will be lost.

In example, if the data that I see on logic analyzer is 0x00000064, on micro I read 0x00000032, and so on. The code that read  is the following:

void writeReadRegister (DeviceHandle_t handle,
                             bool readWrite,
                             Register_t addr,
                             uint32_t* message)
{
    uint8_t txData[6];
    uint8_t rxData[6];
    uint32_t tmpMessage = *message;

    //readWrite = 1 write
    if (readWrite == 1)
    {
        memset(txData, 0, sizeof(txData));
        txData[0] = 0x01;
        txData[1] = (uint8_t)addr;
        txData[2] = (uint8_t)((tmpMessage >> 24) & 0x000000FF);
        txData[3] = (uint8_t)((tmpMessage >> 16) & 0x000000FF);
        txData[4] = (uint8_t)((tmpMessage >>   & 0x000000FF);
        txData[5] = (uint8_t)(tmpMessage         & 0x000000FF);
    }
    //readWrite = 0 read
    else if (readWrite == 0)
    {
        memset(txData, 0, sizeof(txData));
        txData[0] = 0x00;
        txData[1] = (uint8_t)addr;
        memset(rxData, 0, sizeof(rxData));
        rxData[0] = 0x00;
        rxData[1] = (uint8_t)addr;
    }
    handle->xferDefault.txData = txData;
    handle->xferDefault.rxData = rxData;

    GPIO_PinWrite(handle->gpioPeripheral, handle->port, handle->pin, 0);
    App_mDelay(1);

    SPI_MasterTransferBlocking(handle->peripheralNum, &handle->xferDefault);

    App_mDelay(1);
    GPIO_PinWrite(handle->gpioPeripheral, handle->port, handle->pin, 1);

    if (readWrite == 0)
    {
        uint32_t temp = 0;
        temp = (((uint32_t)rxData[5])       & 0x000000FF) |
               (((uint32_t)rxData[4] <<   & 0x0000FF00) |
               (((uint32_t)rxData[3] << 16) & 0x00FF0000) |
               (((uint32_t)rxData[2] << 24) & 0xFF000000);
        *message = temp;

    }
}

Where is the error? I can't see!

Thanks

Marco

[MarcoGiammarini]

Hi, I found the problem: the slave device, an FPGA programmed by ourself, generate a wrong MISO message... so the microcontroller can't read well the data.

Thanks all.

[Alice_Yang]

Hello @MarcoGiammarini 

How about first use the SPI demo under SDK?

BR

Alice

[al_bin]

Try CPHA=1