Tiva C EK-TM4C123GXL Launchpad No Signal On SSI Pins

I am using an EK-TM4C123GXL. At first, I used the sd card example code from the DK-TM4C123G, which appears to have the same pin assignments Port A 2-5 for SSI0. Currently, I simplified everything to just using the SPI peripheral example. Still the same pin assignments PA2-5.  

I have had a few instances of it working with the sd card. I think possibly on the introduction of a pull up resistor on one pin or another. (I've tried various combinations again) I suspect there may be something unstable. So right now I just want to see some signal on the SPI pins. 

It is more likely there is something wrong with the circuit than the something wrong with the code, but I see that the ground pin is connected so I am expecting at least some sort of a signal on the SPI pins, unless I am missing something....

The set up code is as follows, it is unchanged from the spi_master.c example.

    //
    // The SSI0 peripheral must be enabled for use.
    //
    SysCtlPeripheralEnable(SYSCTL_PERIPH_SSI0);

    //
    // For this example SSI0 is used with PortA[5:2].  The actual port and pins
    // used may be different on your part, consult the data sheet for more
    // information.  GPIO port A needs to be enabled so these pins can be used.
    // TODO: change this to whichever GPIO port you are using.
    //
    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);

    //
    // Configure the pin muxing for SSI0 functions on port A2, A3, A4, and A5.
    // This step is not necessary if your part does not support pin muxing.
    // TODO: change this to select the port/pin you are using.
    //
    GPIOPinConfigure(GPIO_PA2_SSI0CLK);
    GPIOPinConfigure(GPIO_PA3_SSI0FSS);
    GPIOPinConfigure(GPIO_PA4_SSI0RX);
    GPIOPinConfigure(GPIO_PA5_SSI0TX);

    //
    // Configure the GPIO settings for the SSI pins.  This function also gives
    // control of these pins to the SSI hardware.  Consult the data sheet to
    // see which functions are allocated per pin.
    // The pins are assigned as follows:
    //      PA5 - SSI0Tx
    //      PA4 - SSI0Rx
    //      PA3 - SSI0Fss
    //      PA2 - SSI0CLK
    // TODO: change this to select the port/pin you are using.
    //
    GPIOPinTypeSSI(GPIO_PORTA_BASE, GPIO_PIN_5 | GPIO_PIN_4 | GPIO_PIN_3 |
                   GPIO_PIN_2);

    //
    // Configure and enable the SSI port for SPI master mode.  Use SSI0,
    // system clock supply, idle clock level low and active low clock in
    // freescale SPI mode, master mode, 1MHz SSI frequency, and 8-bit data.
    // For SPI mode, you can set the polarity of the SSI clock when the SSI
    // unit is idle.  You can also configure what clock edge you want to
    // capture data on.  Please reference the datasheet for more information on
    // the different SPI modes.
    //
#if defined(TARGET_IS_TM4C129_RA0) ||                                         \
    defined(TARGET_IS_TM4C129_RA1) ||                                         \
    defined(TARGET_IS_TM4C129_RA2)
    SSIConfigSetExpClk(SSI0_BASE, ui32SysClock, SSI_FRF_MOTO_MODE_0,
                       SSI_MODE_MASTER, 1000000, 8);
#else
    SSIConfigSetExpClk(SSI0_BASE, SysCtlClockGet(), SSI_FRF_MOTO_MODE_0,
                       SSI_MODE_MASTER, 1000000, 8);
#endif

    //
    // Enable the SSI0 module.
    //
    SSIEnable(SSI0_BASE);

by port file, are you referring to the pin-map.h file? I can see that I am using:

#ifdef PART_TM4C123GH6PM

#define GPIO_PA0_U0RX           0x00000001
#define GPIO_PA0_CAN1RX         0x00000008

#define GPIO_PA1_U0TX           0x00000401
#define GPIO_PA1_CAN1TX         0x00000408

#define GPIO_PA2_SSI0CLK        0x00000802

#define GPIO_PA3_SSI0FSS        0x00000C02

#define GPIO_PA4_SSI0RX         0x00001002

#define GPIO_PA5_SSI0TX         0x00001402

#define GPIO_PA6_I2C1SCL        0x00001803
#define GPIO_PA6_M1PWM2         0x00001805

#define GPIO_PA7_I2C1SDA        0x00001C03
#define GPIO_PA7_M1PWM3         0x00001C05

rvmdk PART_TM4C123GH6PM TARGET_IS_TM4C123_RB1 is defined under Options for Target -> C/C++ tab. However I had not considered the possibility of some included file causing a conflict. I will try creating a fresh project with only the spi_master.c file, as oppose to replacing my main.c file and still compiling the rest of the .c files in my project. 

*accidental double post, deleted

Everything seems to be right as far as I can see... I did notice that the mmc file did not contain the pin multiplexing set up code. i.e

GPIOPinConfigure(GPIO_PA2_SSI0CLK);
GPIOPinConfigure(GPIO_PA3_SSI0FSS);
GPIOPinConfigure(GPIO_PA4_SSI0RX);
GPIOPinConfigure(GPIO_PA5_SSI0TX);

but adding/removing that doesn't appear to make a difference. (This was done in the power_on function) I assume this is because there is only one alternate function available on those pins. 

static
void send_initial_clock_train(void)
{
    unsigned int i;
    uint32_t ui32Dat;

    /* Ensure CS is held high. */
    DESELECT();

    /* Switch the SSI TX line to a GPIO and drive it high too. */
    ROM_GPIOPinTypeGPIOOutput(SDC_GPIO_PORT_BASE, SDC_SSI_TX);
    ROM_GPIOPinWrite(SDC_GPIO_PORT_BASE, SDC_SSI_TX, SDC_SSI_TX);
		ROM_GPIOPinWrite(SDC_GPIO_PORT_BASE, SDC_SSI_TX, 0);					 	//added this
    ROM_GPIOPinWrite(SDC_GPIO_PORT_BASE, SDC_SSI_TX, SDC_SSI_TX); 	//added this
	
    /* Send 10 bytes over the SSI. This causes the clock to wiggle the */
    /* required number of times. */
    for(i = 0 ; i < 10 ; i++)
    {
        /* Write DUMMY data. SSIDataPut() waits until there is room in the */
        /* FIFO. */
        SSIDataPut(SDC_SSI_BASE, 0xFF);

        /* Flush data read during data write. */
        SSIDataGet(SDC_SSI_BASE, &ui32Dat);
    }

    /* Revert to hardware control of the SSI TX line. */
    ROM_GPIOPinTypeSSI(SDC_GPIO_PORT_BASE, SDC_SSI_TX);
}

I added the 2 lines to set the TX pin to 0 and back to 1, and this is clearly visible on the oscilloscope.  

I noticed register DR does not seem to clear after being written to. I'm not sure if this behavior is correct.

static
void power_on (void)
{
    /*
     * This doesn't really turn the power on, but initializes the
     * SSI port and pins needed to talk to the card.
     */

    /* Enable the peripherals used to drive the SDC on SSI */
    ROM_SysCtlPeripheralEnable(SDC_SSI_SYSCTL_PERIPH);
    ROM_SysCtlPeripheralEnable(SDC_GPIO_SYSCTL_PERIPH);

//    GPIOPinConfigure(GPIO_PA2_SSI0CLK);
//    GPIOPinConfigure(GPIO_PA3_SSI0FSS);
//    GPIOPinConfigure(GPIO_PA4_SSI0RX);
//    GPIOPinConfigure(GPIO_PA5_SSI0TX);
	
    /*
     * Configure the appropriate pins to be SSI instead of GPIO. The FSS (CS)
     * signal is directly driven to ensure that we can hold it low through a
     * complete transaction with the SD card.
     */
    ROM_GPIOPinTypeSSI(SDC_GPIO_PORT_BASE, SDC_SSI_TX | SDC_SSI_RX | SDC_SSI_CLK);
    ROM_GPIOPinTypeGPIOOutput(SDC_GPIO_PORT_BASE, SDC_SSI_FSS);

    /*
     * Set the SSI output pins to 4MA drive strength and engage the
     * pull-up on the receive line.
     */
    MAP_GPIOPadConfigSet(SDC_GPIO_PORT_BASE, SDC_SSI_RX, GPIO_STRENGTH_4MA, GPIO_PIN_TYPE_STD_WPU);
    MAP_GPIOPadConfigSet(SDC_GPIO_PORT_BASE, SDC_SSI_CLK | SDC_SSI_TX | SDC_SSI_FSS, GPIO_STRENGTH_4MA, GPIO_PIN_TYPE_STD);

    /* Configure the SSI0 port */
    ROM_SSIConfigSetExpClk(SDC_SSI_BASE, ROM_SysCtlClockGet(), SSI_FRF_MOTO_MODE_0, SSI_MODE_MASTER, 50000, 8); //changed from 400000
    ROM_SSIEnable(SDC_SSI_BASE);

    /* Set DI and CS high and apply more than 74 pulses to SCLK for the card */
    /* to be able to accept a native command. */
    send_initial_clock_train();

    PowerFlag = 1;
}