TIVA C TM4C123G SPI code, but not working. Thanks!

Hi,

I am using the TIVA board to acquire the data from ADS1299 EVM daughter board via SPI. 

I initialized the ADS1299 and then write/read register to/from it. But the value read is 0.  This is the code. Thank you! 

Qi

// INCLUDE
#include <stdint.h>
#include <stdbool.h>
#include "inc/hw_memmap.h"
#include "inc/hw_types.h"
#include "driverlib/debug.h"
#include "driverlib/fpu.h"
#include "driverlib/gpio.h"
#include "driverlib/pin_map.h"
#include "driverlib/rom.h"
#include "driverlib/sysctl.h"
#include "driverlib/uart.h"
#include "utils/uartstdio.h"
#include "math.h"
#include "stdio.h"
#include "inc/hw_ssi.h"
#include "driverlib/ssi.h"

// DEFINE
#define ADS_WAKEUP 	0x2
#define ADS_STANDBY	0x4
#define ADS_RESET 	0x6
#define ADS_START 	0x8
#define ADS_STOP 	0xA

#define ADS_RDATAC	0x10
#define ADS_SDATAC	0x11
#define ADS_RDATA	0x12

#define ADS_RREG	0x20
#define ADS_WREG	0x40

// GLOBAL VARIABLES
uint32_t read_value;
uint32_t value;
uint32_t value2;

uint32_t inst1;
uint32_t inst2;


//SUBFUNCTIONS
void LEDTwinkleTwice();
void ADS1299_SysCmdWrite(uint32_t value);
void ADS1299_ReadCmdWrite(uint32_t value);
void ADS1299_RegWrite(uint32_t adres,uint32_t value);
uint32_t ADS1299_RegRead(uint32_t adres2);


//MAIN FUNCTION
//3 steps. (step 1) config: clock/ssi/gpio/interrupt  (step 2) config ADS1299 via SPI  (step 3) acquire DATA from ADS1299
int main(void)
{
	unsigned long ulindex=0;
	unsigned long rxindex=0;
	unsigned long ulData=0;
	unsigned long rxData[16]={0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF};
	unsigned long try=1;
	unsigned long clockget=0;
	unsigned int rxDataOne = 0xFF;

	unsigned int reg_start_adress=0xFF;
	unsigned int reg_number=0xFF;
	unsigned int reg_value=0xFF;

	//(step 1) config: clock/ssi/gpio/interrupt----------------------------------------------------------------------------------------------
	//CONFIG CLOCK: 50MHz
	SysCtlClockSet(SYSCTL_SYSDIV_4 | SYSCTL_USE_PLL | SYSCTL_OSC_MAIN | SYSCTL_XTAL_16MHZ);
	clockget = SysCtlClockGet();

	//CONFIG GPIO&SSI: SSI0 master
	SysCtlPeripheralEnable(SYSCTL_PERIPH_SSI0);
	SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);

	GPIOPinConfigure(GPIO_PA2_SSI0CLK);
	GPIOPinConfigure(GPIO_PA3_SSI0FSS);
	GPIOPinConfigure(GPIO_PA4_SSI0RX);
	GPIOPinConfigure(GPIO_PA5_SSI0TX);
	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,10000, 8);
	SSIEnable(SSI0_BASE);

	//CONFIG GPIO:
	SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOE);
	GPIOPinTypeGPIOOutput(GPIO_PORTE_BASE, GPIO_PIN_1); //output, ADS SPI ~RESET,
	GPIOPinTypeGPIOOutput(GPIO_PORTE_BASE, GPIO_PIN_2); //output, ADS SPI START,
	GPIOPinTypeGPIOOutput(GPIO_PORTE_BASE, GPIO_PIN_4); //output, ADS SPI ~CS,
	GPIOPinTypeGPIOInput(GPIO_PORTE_BASE, GPIO_PIN_5);  //input,  ADS SPI ~DRDY (interrupt)

	GPIOPinWrite(GPIO_PORTE_BASE, GPIO_PIN_1, GPIO_PIN_1); //RESET=1
	GPIOPinWrite(GPIO_PORTE_BASE, GPIO_PIN_2, 0); 		   //START=0
	GPIOPinWrite(GPIO_PORTE_BASE, GPIO_PIN_4, GPIO_PIN_4);  //CS=1

	//(step 2) config ADS1299 via SPI  ----------------------------------------------------------------------------------------------
	//(1) POR (2)RESET (3) issue SPI CS (4) SDATAC, write REG, read REG
	SysCtlDelay(8000000);						//(1) power up setup, poweronReset/OSC startup: 2power16 tclk of ADS
	GPIOPinWrite(GPIO_PORTE_BASE, GPIO_PIN_1,0); 			//(2) RESET=0
	SysCtlDelay(100000);						//(2) wait more than 2 tclk + 18 tclk
	GPIOPinWrite(GPIO_PORTE_BASE, GPIO_PIN_1,GPIO_PIN_1); 	//(2) RESET=1
	SysCtlDelay(100000);
	GPIOPinWrite(GPIO_PORTE_BASE,GPIO_PIN_4, 0); 			//(3) SPI CS=0
	SysCtlDelay(8000000);

	SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOF); 			//LED for debug
	GPIOPinTypeGPIOOutput(GPIO_PORTF_BASE, GPIO_PIN_2);     //LED for debug
	GPIOPinWrite(GPIO_PORTF_BASE,GPIO_PIN_2, GPIO_PIN_2);   //LED for debug
	GPIOPinWrite(GPIO_PORTF_BASE,GPIO_PIN_2, 0);			//LED for debug

	SSIDataPut(SSI0_BASE,ADS_SDATAC);   					//(4) SDATAC: stop ADS conversion command
	while(SSIBusy(SSI0_BASE));
    SysCtlDelay(100000);
    										//(4) write ADS reg: address (0x01-ADS CONFIG0), value(0x95), write 1 time
    reg_start_adress = 0x01;
    reg_number = 0x0; //0 represents 1 reg
    reg_value = 0x95;

    SSIDataPut(SSI0_BASE, ADS_WREG | (reg_start_adress & 0x1F));
    while(SSIBusy(SSI0_BASE));
    SysCtlDelay(100000);

    SSIDataPut(SSI0_BASE,reg_number);
    while(SSIBusy(SSI0_BASE));
    SysCtlDelay(100000);

    SSIDataPut(SSI0_BASE,reg_value);
    while(SSIBusy(SSI0_BASE));
    SysCtlDelay(100000);

			/(4) read ADS reg: address (0x01-ADS CONFIG0), read 1 time
    SSIDataPut(SSI0_BASE, ADS_RREG | (reg_start_adress & 0x1F));
    while(SSIBusy(SSI0_BASE));
    SysCtlDelay(100000);

    SSIDataPut(SSI0_BASE,reg_number);
    while(SSIBusy(SSI0_BASE));
    SysCtlDelay(100000);

    SSIDataPut(SSI0_BASE,0xFF); //dummy SPI write to get SPI RX data, which is prepared for ADS CONFIG0
    while(SSIBusy(SSI0_BASE));
    SysCtlDelay(100000);


    for(ulindex = 0; ulindex <= 6; ulindex++)
   //rx data 0 - 5 should be 0, data 6 should be 0x95 from ADS register, but it is still 0
    {	    //
    	// Wait until there is data to be read.
    	SSIDataGet(SSI0_BASE, &rxDataOne);
    	while(SSIBusy(SSI0_BASE));

    	rxData[ulindex] = rxDataOne;
    	try++;
    }

    try++;
}