ADS1218: Invalid data coming from ADC ads1218 interfaced with arduino UNO

 
#include <SPI.h>
#define RESET 0x06                                                    //Send the RESET command (06h) to make sure the ADS1220 is properly reset after power-up
#define START 0x08                                         //Send the START/SYNC command (08h) to start converting in continuous conversion mode

// define the ads1218 command
#define RDATA 0x01    // read the latest ad conversion data
#define WREG 0x50     // 2 byte command, write data to register 0-15
#define DSYNC 0xFC    // Sync DRDY
#define RESET 0xFE    // reset the register to the power of the data, stop the continuous read mode, does not affect the ram data


#define ADS1218_CS_PIN 7
#define ADS1218_DRDY_PIN 6
int32_t stat;

void syncSerialData(void)   
{
  noInterrupts();
  digitalWrite(ADS1218_CS_PIN, LOW);
  delayMicroseconds(500);
  SPI.transfer(DSYNC);
  delayMicroseconds(500);
  digitalWrite(ADS1218_CS_PIN, HIGH);
  interrupts();
  delay(2000);

}

void waitForDataReady(int timeOut)  //wait for data ready
{
  // wait for /DRDY = 1
  while ((digitalRead(ADS1218_DRDY_PIN)) != LOW);

  // wait for /DRDY = 0
  while ((digitalRead(ADS1218_DRDY_PIN)) == LOW);
}


void setup()
{
pinMode(ADS1218_CS_PIN, OUTPUT);
digitalWrite(ADS1218_CS_PIN, HIGH);
Serial.begin(9600);           
  SPI.begin();                          
  SPI.setBitOrder(MSBFIRST);
  SPI.setDataMode(SPI_MODE1);
  SPI.setClockDivider(SPI_CLOCK_DIV16); // SCLK upto 4tosc periods

  // setup register (00)
   SPI.transfer(0x50);
   SPI.transfer(0x1E); //speed:4Mhz ; fmod:fosc/256,ref enable,2.5Vref,,buffer enable,bit order:0 MSB first
  
  
  // Setting the MUX register channel requirement
  SPI.transfer(0x51);// write command: 0101 mux address(01)
  SPI.transfer(0x05); // wreg -1(6 register to write due to 6 channels)
  SPI.transfer(0x01); // ain0 and ain1 

  // Write command to address 02
  SPI.transfer(0x52); // analog control register
  SPI.transfer(0x00);// PGA set to 1
  
  syncSerialData();    // Sync Data Ready with Serial clock edge
  delay(50); 

}

void loop()
{

digitalWrite(ADS1218_CS_PIN, LOW);                        //Take CS low
SPI.transfer(RDATA);
delayMicroseconds(12.5); // used:4Mhz (50tosc))

stat= SPI.transfer(0) ;
stat = (stat<<8) | SPI.transfer(0); 
stat = (stat<<8) | SPI.transfer(0);
digitalWrite(ADS1218_CS_PIN, HIGH);                 //  Clear CS to high
if (stat & 0x800000 )
{
  stat = (stat | 0xFF000000);
}
Serial.println(stat);
delay(50); // 
}