SPI Problem with TiVac EK-TM4C1294XL

Hello,

Thank you for your prompt answer. There is 3,3V even if the PQ2 pin is connected to the CC1110. The problem appears when the SPI communication begins.

As you can see on the picture linked. On idle state (when there is no SPI communication), there is 3,3V on PQ2 pin. When the SPI communication begins, the voltage drops to 1,8V. When it ends, the voltage go back to 3,3V.

Please also find linked the source code that I am using for the Cortex-M4.

Thank you in advance for your help.

Best regards,

Yannick

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/*
 *  ======== spiloopback.c ========
 */
/* XDCtools Header files */
#include <xdc/std.h>
#include <xdc/cfg/global.h>
#include <xdc/runtime/System.h>

/* BIOS Header files */
#include <ti/sysbios/BIOS.h>

/* TI-RTOS Header files */
#include <ti/drivers/GPIO.h>
#include <ti/drivers/SPI.h>

/* Example/Board Header files */
#include "Board.h"

#define SPI_MSG_LENGTH    20

/* Allocate buffers in .dma section of memory for concerto devices */
#ifdef MWARE
#pragma DATA_SECTION(slaveRxBuffer, ".dma");
#pragma DATA_SECTION(slaveTxBuffer, ".dma");
#endif

unsigned char slaveRxBuffer[SPI_MSG_LENGTH]="hello";
unsigned char slaveTxBuffer[SPI_MSG_LENGTH] =  "Hello, this is slav";
/* *  ======== slaveTaskFxn ========
 *  Task function for slave task.
 *
 *  This task runs on a higher priority, since slave
 *  has to be ready for master. Slave SPI sends a
 *  message to master and also receives message from
 *  master. Task for this function is created
 *  statically. See the project's .cfg file.
 */
Void slaveTaskFxn (UArg arg0, UArg arg1)
{
    SPI_Handle slaveSpi;
    SPI_Params slaveSpiParams;
    SPI_Transaction slaveTransaction;
    bool transferOK;

    /* Initialize SPI handle with slave mode */
    SPI_Params_init(&slaveSpiParams);
    slaveSpiParams.mode = SPI_SLAVE;
   // slaveSpiParams.

    slaveSpi = SPI_open(Board_SPI1, &slaveSpiParams);
    if (slaveSpi == NULL) {
        System_abort("Error initializing SPI\n");  System_flush();
    }
    else {
        System_printf("SPI initialized\n");  System_flush();
    }

    /* Initialize slave SPI transaction structure */
    slaveTransaction.count = SPI_MSG_LENGTH;
    slaveTransaction.txBuf = NULL;//(Ptr)slaveTxBuffer;
    slaveTransaction.rxBuf = (Ptr)slaveRxBuffer;

    while(1)
    {
		/* Initiate SPI transfer */
		transferOK = SPI_transfer(slaveSpi, &slaveTransaction);

		if(transferOK) {
			/* Print contents of slave receive buffer */
			System_printf("Slave: %d\n", slaveRxBuffer[0]);  System_flush();
		}
		else {
			System_printf("Unsuccessful slave SPI transfer");  System_flush();
		}
    }

    /* Deinitialize SPI */
    SPI_close(slaveSpi);
}

/*
 *  ======== main ========
 */
int main(void)
{
    /* Call board init functions. */
    Board_initGeneral();
    Board_initGPIO();
    Board_initSPI();

    /* Turn on user LED */
    GPIO_write(Board_LED0, Board_LED_ON);

    System_printf("Starting the SPI loop-back example\nSystem provider is set to"
                  " SysMin. Halt the target to view any SysMin contents in ROV.\n");
    /* SysMin will only print to the console when you call flush or exit */
    System_flush();
    System_printf("This example requires external wires to be connected to the "
                  "header pins. Please see the Getting Started Guide for "
                  "details.\n");
    /* SysMin will only print to the console when you call flush or exit */
    System_flush();

    /* Start BIOS */
    BIOS_start();

    return (0);
}

Hello Amit,

Amit Ashara said:

2. Check the GPIO Port Q configuration of the SSI3 module using the debugger to see if they are in SSI mode

I checked the GPIO_PCTL register that is equal to 0x0000EEEE which means, according to the linked picture that the PORTQ GPIO's are well configured.

So if I understand well, the PQ2 acts as MOSI pin, so everything is well configured... Moreover I use an example I just modified to only test the slave task, so normally it should work !

Thanks again,

Best Regards,

Yannick

Hello,

the problem is here again even with the resistor desoldered. Can you send to me the bare metal code that you used to make it work ?

Thank you in advance,

Best regards,

Yannick Riou

Finally ! I found that the PQ2 is acting as TX and I was connecting the CC1110 to the SSI3 according to the getting started documentation shipped with the evaluation board. I switched PQ2 and PQ3 and now it's working well ! But I don't manage to understand why I need to switch the two pin's.

Best Regards,

Yannick