TMDX654IDKEVM: SPi test header J20 chip select pin

Hi Johnny,

SPI1_CS0 and SPI1_CS1 are connected to Display controller and HDMI controller respectively.

You have to populate the resistors for CS to go to the test header.

This is documented in IDK user guide under Ch 3.3.14.

https://www.ti.com/lit/ug/spruim6/spruim6.pdf?ts=1596065930431&ref_url=https%253A%252F%252Fwww.ti.com%252Ftool%252FTMDX654IDKEVM

Regards,
Stanley

Hi Stanley,

Thanks for your reply.

I soldered a bridge onto R316 and I can see the CS1 signal on the test header switching successfully.

I am however experiencing issues with receiving the correct data in my receive buffer of the SPI transaction. Please see below:

1. I first set the SPI_v1_HWAttrs of SPI instance 1 as follow:

    SPI_socGetInitCfg(1, &spiCfg);
    spiCfg.baseAddr = CSL_MCSPI1_CFG_BASE;
    spiCfg.enableIntr = 0;
    spiCfg.chNum      = 1;
    SPI_socSetInitCfg(1, &spiCfg);

2. I then call the SPI_Params_Init function and use the default parameters (SPI_POL0_PHA0 and 1Mhz clock) which is compatible with the external SPI device.

3. I then open the SPI instance:

hSpi1 = SPI_open(1, &spiParams);

I now need to send the 0x05 byte over SPI to the external FRam device, which should return 1 byte as can be seen in the datasheet:

I thus set up a SPI transaction as follow:

uint8_t framRxBuf[100];
uint8_t framTxBuf[100];
uint32_t transferLength;

while(1)
    {

        //To read status register
        framTxBuf[0] = RDSR; //0x05 = RDSR
        transferLength = 2;

        //Initialize the SPI transaction
        transaction.count = transferLength;
        transaction.txBuf = framTxBuf;
        transaction.rxBuf = framRxBuf;

        //Make the transaction, and store the reply that has been received in the framRxBuf
        SPI_transfer(hSpi1, &transaction);

        Task_sleep(1000);
    }

I am expecting to receive the "0 1 0 0 0 0 0 0" in my receive buffer now. However, as can be seen in my receive buffer, the data received is all 0 (breakpoint at task_sleep):

When I measure the data output pin of the external SPI device connected to the DI pin on the test header, I see the correct signal. The first 8 clocks is during the RDSR command, whereas the second 8 clocks is the data that is being sent out on the output line of the external SPI device. From the below measurement it is clear that the expected " 0 1 0 0 0 0 0 0" is in fact sent back to the EVM:

Do you now what I am doing wrong in my software that I am not receiving the correct data that is actually being transmitted? What should the count member of the transaction be equal to? Should it include the size of the whole transaction (MOSI + MISO bytes) or only the MOSI bytes? I can also confirm that my hardware connection is correct. I tried changing the count size of the transaction, however that does nothing and only increases the amount of 0's I receive on the rxBuf.

This leads me to think that either my SPI parameter settings is incorrect, hardware failure or just complete incorrect use of the SPI_transfer API.

I look forward to hearing a reply soonest.

Kind regards,

Johnny Smith

Maybe just an update. When I port my source code into the example rtos application, my SPI transaction is working. There is thus some setting not set up correctly either in my .cfg, initmmu function or something.

I commented out all other functionality in the actual application with only the SPI task running. This however does not work. I am continuing to investigate, but I will appreciate a reply in the meantime.

Kind regards,

Johnny Smith

The pin mux was not for my board. After changing the pin mux, receiving data works as expected.

Thank you for your help.