TM4C1294NCPDT: ADS1292R Interface with TM4C1294NCPDT TIVA C micro controller

HI,

I am trying to interfece ADS1292R ECG AFE with TM4C1294NCPDT TIVA C micro controller.

I have configured SSI0 as below.

void SPI_Setup()
{
SysCtlPeripheralEnable(SYSCTL_PERIPH_SSI0);

SSIDisable(SSI0_BASE);

GPIOPinConfigure(GPIO_CONFIG_SSI0CLK);
GPIOPinConfigure(GPIO_CONFIG_SSI0RX);
GPIOPinConfigure(GPIO_CONFIG_SSI0TX);
GPIOPinConfigure(GPIO_PA3_SSI0FSS);

GPIOPinTypeSSI(GPIO_PORTA_BASE, (GPIO_PIN_2 | GPIO_PIN_4 | GPIO_PIN_5 | GPIO_PIN_3 )); // SPI0
SSIAdvModeSet(SSI0_BASE,SSI_ADV_MODE_LEGACY);
SSIConfigSetExpClk(SSI0_BASE,                                                                                                              // SPI0
40000000,                                                                                                                                                    // System Clock for SSI clock
SSI_FRF_MOTO_MODE_1,                                                                                                                       // Data frame format (polarity 0, phase 1)
SSI_MODE_MASTER,                                                                                                                                // Configure as Master
SSI0_SPEED,                                                                                                                                             // Set speed
8);                                                                                                                                                               // Byte-long word length

SSIEnable(SSI0_BASE);

}

My Connections are shown in the attached file 

     TIVA C Controller---- ADS1292R

PN4 ------ARD_PWDN/RESET

PQ0------ARD_START

PQ1------ARD_DRDY

PA3-------ARD_CS

PA4-------ARD_MOSI

PA5-------ARD_MISO

PA2------ARD_SCK

I am trying to write the registers of ADS1292R through TIVA C controller. I could see the data and clock on oscilloscope as expected but I am unable to confirm if the ADS has received data properly.

I have followed the data sheet of ADS to write single register in following way

First byte----Write Opcode | Register address

Second Byte--- (no of registers to write-1)

Third Byte----- Register Data

Now I tried back to read the written register, what I expect is to read the value back which I have written already, Read is done through following way.

First byte----read Opcode | Register address

Second Byte--- (no of registers to read-1)

Third Byte----- 0x00 

But I am unable to read the written value back.I am reading some other value from same register. Hence I am unable to understand where the issue is.

Also is the values read from registers is of 2's complement format or not?

NOTE: RESET bar pin of ADS is held high before performing SPI writes.

Expecting a quick reply.

Thanks and Regards,

Janardan M