CCS/TM4C129XNCZAD: 20 bit data transfer from microcontroller to DAC

Dear all,

        i am using eval ad5791 board and trying to communicate with tm4c129x of texas instruemnts. i am sending data through serial interface(SSI) . but i am unable to get any output. i have checked that VDD=14V Vss=-14 , Vcc=3.3V iovcc=3.3 V , LDAC=0, RESET =1 clr=1 in which LDAC is parmanently shorted to gnd. .RESET is shorted iovcc. and clr is at logic 1 and i am

sending data in 8 bit mode so i am sending in 3 cycle. in very first time i sent data 0x20012. and then 0x1fffff to get full output but iam unable to get any output. please help me to get output. i have attached the code

#include "stdbool.h"
#include "stdint.h"
#include "gpio.h"
#include "rom_map.h"
#include "sysctl.h"
#include "hw_memmap.h"
#include "pin_map.h"
#include "emac.h"
#include "systick.h"
#include "utils/ustdlib.h"
#include "math.h"
#include "driverlib/ssi.h"
#include "tm4c129xnczad.h"
#include "driverlib/rom.h"

uint32_t pui32DataTx=0;
uint32_t pui32DataTx1=0;
uint32_t pui32DataTx2=0;
uint32_t pui32DataTx3=0;

void SSi_data(void);
void dac_normal(void);
void DAC_ldac(void);
#define GPIO_PA2_SSI0CLK        0x0000080F
#define GPIO_PA3_SSI0FSS        0x00000C0F
#define  GPIO_PA4_SSI0RX      0x0000100F
#define GPIO_PA5_SSI0TX      0x0000140F
#define NUM_SSI_DATA            3
#define SYS_TICK_DELAY 10000

uint32_t ui32SysClock;

void DAC_ldac()
    {
        MAP_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOS);
        MAP_GPIOPinTypeGPIOOutput(GPIO_PORTS_BASE, GPIO_PIN_7); // sync pulse
        MAP_GPIOPinTypeGPIOOutput(GPIO_PORTS_BASE, GPIO_PIN_6);  //clr high
        MAP_GPIOPinWrite(GPIO_PORTS_BASE, GPIO_PIN_7, GPIO_PIN_7); //sync pulse high 
        MAP_GPIOPinWrite(GPIO_PORTS_BASE, GPIO_PIN_6, GPIO_PIN_6);
   
    }


void dac_normal()
{
    pui32DataTx = 0x200312;
    SSi_data();
   // pui32DataTx = 0x400002;
  //  SSi_data();

}



void SSi_data()
{

 pui32DataTx1= pui32DataTx & 0x0000ff;
 pui32DataTx2= (pui32DataTx & 0x00ff00) >> 8;
 pui32DataTx3= (pui32DataTx & 0xff0000) >> 16;
 MAP_GPIOPinWrite(GPIO_PORTS_BASE, GPIO_PIN_7, 0);

 SSIDataPut(SSI0_BASE, pui32DataTx3);
 
                      MAP_GPIOPinWrite(GPIO_PORTS_BASE, GPIO_PIN_6, 0); //sync low
                     while(SSIBusy(SSI0_BASE))
                            {
                            }
 SSIDataPut(SSI0_BASE, pui32DataTx2);

                     while(SSIBusy(SSI0_BASE))
                            {
                            }
 SSIDataPut(SSI0_BASE, pui32DataTx1);

                     while(SSIBusy(SSI0_BASE))
                            {
                            }


                          SSIIntClear(SSI0_BASE,SSI_RXFF);
                          MAP_GPIOPinWrite(GPIO_PORTS_BASE, GPIO_PIN_7, GPIO_PIN_7); // Sync high
                          
                         
                         
}
int main(void)
{

        ui32SysClock = SysCtlClockFreqSet((SYSCTL_XTAL_25MHZ |SYSCTL_OSC_MAIN | SYSCTL_USE_PLL | SYSCTL_CFG_VCO_320),
        10000000);
        SysCtlPeripheralEnable(SYSCTL_PERIPH_SSI0);
        SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);
        SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);
        GPIOPinConfigure(GPIO_PA2_SSI0CLK);
        GPIOPinConfigure(GPIO_PA3_SSI0FSS);
        GPIOPinConfigure(GPIO_PA4_SSI0RX);
        GPIOPinConfigure(GPIO_PA5_SSI0TX);
        DAC_ldac();
        MAP_GPIOPinWrite(GPIO_PORTS_BASE, GPIO_PIN_7, GPIO_PIN_7);
        GPIOPinTypeSSI(GPIO_PORTA_BASE, GPIO_PIN_5 | GPIO_PIN_4 | GPIO_PIN_3 | GPIO_PIN_2);
        SSIConfigSetExpClk(SSI0_BASE, SysCtlClockGet(), SSI_FRF_MOTO_MODE_0,
                               SSI_MODE_MASTER, 100000, 8);
        SSIEnable(SSI0_BASE);
        dac_normal();


        while(1)
        {
                          pui32DataTx = 0x1fffff;
                          SSi_data();
                          
        }
    //return 0;
}

yes i have hardwired it correctly and i am observing at oscilloscope too but output is 0v on any input