CCS/LAUNCHXL-F28379D: SPI communication between two f28379D launchpads

Mori,

There some incorrect configuration on both SPI master and SPI slave code.I have summarized them which would be useful for making corrections in your code.

Key changes to master mode code:

    - Disable Loop back mode. This mode is for testing purposes only which is useful for testing SPI in standalone mode (without another SPI slave).
        SpiaRegs.SPICCR.all =0x008F;

    - It looks like you don't seem to be using SPI FIFO. So, make sure to disable FIFO
        SpiaRegs.SPIFFTX.bit.SPIFFENA = 0;

    - Enable SPIINTENA to generate INT_FLAG bit on completion of SPI transmission
        SpiaRegs.SPICTL.bit.SPIINTENA = 1;
        
    - From your code, you have configured SPI as master transmitter mode correctly
        SpiaRegs.SPICTL.bit.MASTER_SLAVE = 1; //Master mode
        SpiaRegs.SPICTL.bit.TALK         = 1; //Trasnmit mode enabled
    
    - Change you infinite loop look as shown below
        for(;;)
        {
            // Transmit data
            spi_xmit(sdata);
            while(!SpiaRegs.SPISTS.INT_FLAG); //Wait till SPI complete transmission
        }

Key changes to slave mode code:
    
    - Disable Loop back mode. This mode is for testing purposes only which is useful for testing SPI in standalone mode (without another SPI slave).
        SpiaRegs.SPICCR.all =0x008F;
    
    - Make sure to configure slave as slave receiver as shown below
        SpiaRegs.SPICTL.bit.MASTER_SLAVE = 0; //Slave mode
        SpiaRegs.SPICTL.bit.TALK                   = 0; //Receiver mode enabled
        
    - It looks like you don't seem to be using SPI FIFO. So, make sure to disable FIFO
        SpiaRegs.SPIFFTX.bit.SPIFFENA         = 0; //Disable SPI FIFO
        SpiaRegs.SPIFFRX.bit.RXFIFORESET = 0; //Hold SPI RX FIFO in reset

    - Enable SPIINTENA to generate INT_FLAG bit on completion of SPI transmission
        SpiaRegs.SPICTL.bit.SPIINTENA = 1;
        
    - I don't understand the role of GPIO19 from your SPI slave example code.
    
    - Wait for INT_FLAG to indicate SPI has received information
    
        while(!SpiaRegs.SPISTS.INT_FLAG);
        rdata = SpiaRegs.SPIRXBUF;

Regards,

Manoj

Dear Manoj,

Thank you so much for your help. I have gone through your comments.

It seems that still there is a problem in my code. Unfortunately, I cannot understand whether it is from the master side or the slave side.

************************************************************

Master:

   sdata = 1;
   for(;;)
   {    
     // Transmit data
     spi_xmit(sdata);
     while(!SpiaRegs.SPISTS.bit.INT_FLAG); //Wait till SPI complete transmission
   }

void error(void)
{
    asm("     ESTOP0");                        // Test failed!! Stop!
    for (;;);
}

void spi_init()
{    

    SpiaRegs.SPIBRR.all =0x007F;
    SpiaRegs.SPIPRI.bit.FREE = 1;                // Set so breakpoints don't disturb xmission

        // Set reset low before configuration changes
        // Clock polarity (0 == rising, 1 == falling)
        // 16-bit character
        // Enable loop-back
        SpiaRegs.SPICCR.bit.SPISWRESET = 0;
        SpiaRegs.SPICCR.bit.CLKPOLARITY = 0;
        SpiaRegs.SPICCR.bit.SPICHAR = (16-1);
        SpiaRegs.SPICCR.bit.SPILBK = 0;

        SpiaRegs.SPICTL.bit.MASTER_SLAVE = 1;
        SpiaRegs.SPICTL.bit.TALK = 1;
        SpiaRegs.SPICTL.bit.CLK_PHASE = 0;
        SpiaRegs.SPICTL.bit.SPIINTENA = 1; //Enable SPIINTENA to generate INT_FLAG bit on completion of SPI transmission

}

void spi_xmit(Uint16 a)
{
    SpiaRegs.SPITXBUF=a;
}

void spi_fifo_init()                                        
{

    SpiaRegs.SPIFFTX.bit.SPIFFENA = 0;
}  

Slave:

 for(;;)
   {

        while(!SpiaRegs.SPISTS.bit.INT_FLAG);
       rdata = SpiaRegs.SPIRXBUF;
   }

void spi_init()
{

        SpiaRegs.SPICTL.bit.MASTER_SLAVE = 0;
        SpiaRegs.SPICTL.bit.TALK = 0; //Receiver mode enabled
        SpiaRegs.SPICTL.bit.CLK_PHASE = 0;
        SpiaRegs.SPICTL.bit.SPIINTENA = 1;

        // Set reset low before configuration changes
        // Clock polarity (0 == rising, 1 == falling)
        // 16-bit character
        // Enable loop-back
        SpiaRegs.SPICCR.bit.SPISWRESET = 0;
        SpiaRegs.SPICCR.bit.CLKPOLARITY = 0;
        SpiaRegs.SPICCR.bit.SPICHAR = (16-1);
        SpiaRegs.SPICCR.bit.SPILBK = 0;

        SpiaRegs.SPIBRR.all =0x007F;
        SpiaRegs.SPIPRI.bit.FREE = 1;    // Set so breakpoints don't disturb

}

//
// spi_fifo_init - Initialize SPI FIFO registers
//
void spi_fifo_init()
{
//    SpiaRegs.SPIFFTX.all = 0xE040;
//    SpiaRegs.SPIFFRX.all = 0x2044;
//    SpiaRegs.SPIFFCT.all = 0x0;
    SpiaRegs.SPIFFRX.bit.RXFFIL = 0x00;                      // 4:0    Interrupt level
    SpiaRegs.SPIFFRX.bit.RXFFIENA =0;                        // 5      Interrupt enable0
    SpiaRegs.SPIFFRX.bit.RXFFINTCLR = 0;                     // 6      Clear INT flag
    SpiaRegs.SPIFFRX.bit.RXFFINT = 0;                        // 7      INT flag
    SpiaRegs.SPIFFRX.bit.RXFFST = 0;                         // 12:8   FIFO status
    SpiaRegs.SPIFFRX.bit.RXFIFORESET = 0;                    // 13     FIFO reset
    SpiaRegs.SPIFFRX.bit.RXFFOVFCLR = 0;                     // 14     Clear overflow
    SpiaRegs.SPIFFRX.bit.RXFFOVF = 0;                        // 15     FIFO overflow

    SpiaRegs.SPIFFCT.all=0x0;

}

**********************************************

It seems to me that the program get stuck on "while(!SpiaRegs.SPISTS.bit.INT_FLAG)".

Would you please tell me where is the problem?

Best regards,

Mori

Mori,

It looks like you have forgotten to set  SpiaRegs.SPICCR.bit.SPISWRESET = 1. Unless you set SPISWRESET =1, SPI neither transmit (or) receive. This problem is there in both transmitter and receiver side.

I would encourage to probe oscilloscope signals to see whether SPI is transmitting.

Regards,

Manoj