TMS320F28377D: driverLib SPI initialization

Is there additional driverLib initialization required for a very simple SPI example?  Please see the code below.

The data in present in the SPITXBUF register when debugging (0x014D = 333), but there is no data or clock present on the controlCard pins when viewed with a scope.  Checking pins 67 (SPISIMOA), 69 (SPISOMIA), and 71 (SPICLKA).

What have a missed?

Kindly,

Graham

#include "F28x_Project.h"

#include "driverlib/spi.h"

/**
 * main.c
 */
  void main(void)
  {
      uint32_t delay;

      InitSysCtrl();

      SPI_disableModule(SPIA_BASE);

      SPI_setConfig(SPIA_BASE,  100000000,  SPI_PROT_POL0PHA0, SPI_MODE_MASTER,  500000,  16);

      SPI_enableModule(SPIA_BASE);

      while (1)
      {
          SPI_writeDataNonBlocking(SPIA_BASE, 333 );

          // Delay for a bit.
          for(delay = 0; delay < 2000000; delay++)
          {}
      }
  }