ADS1256: Verifying Number of Samples per Second Output w.r.t Sampling Rate

#include <SPI.h>#include <arduinoFFT.h>#define cs 5 // chip select#define rdy 22 // data ready, input#define rst 21 // may omit#define SPISPEED 2500000   // Teensy 3.2 @120 mhz#define SAMPLES 1024float value1;float value2;float value3;int i;float x;double VREF = 2.50;#define DEBUG 1double k[SAMPLES];void setup(){  Serial.begin(115200);  pinMode(cs, OUTPUT);  digitalWrite(cs, LOW); // tied low is also OK.  pinMode(rdy, INPUT);  pinMode(rst, OUTPUT);  digitalWrite(rst, LOW);  delay(1); // LOW at least 4 clock cycles of onboard clock. 100 microseconds is enough  digitalWrite(rst, HIGH); // now reset to default values  delay(100);  SPI.begin(); //start the spi-bus  delay(100);  while (digitalRead(rdy)) {}  // wait for ready_line to go low  SPI.beginTransaction(SPISettings(SPISPEED, MSBFIRST, SPI_MODE1)); // start SPI  digitalWrite(cs, LOW);  delayMicroseconds(100);  SPI.transfer(0xFE);  delay(5);  byte status_reg = 0x00 ;  // address (datasheet p. 30)  byte status_data = 0x01; // 01h = 0000 0 0 0 1 => status: Most Significant Bit First, Auto-Calibration Disabled, Analog Input Buffer Disabled  //byte status_data = 0x07; // 01h = 0000 0 1 1 1 => status: Most Significant Bit First, Auto-Calibration Enabled, Analog Input Buffer Enabled  SPI.transfer(0x50 | status_reg);  SPI.transfer(0x00);   // 2nd command byte, write one register only  SPI.transfer(status_data);   // write the databyte to the register  delayMicroseconds(100);   byte adcon_reg = 0x00; //A/D Control Register (Address 02h)  //byte adcon_data = 0x20; // 0 01 00 000 => Clock Out Frequency = fCLKIN, Sensor Detect OFF, gain 1  byte adcon_data = 0x00; // 0 00 00 000 => Clock Out = Off, Sensor Detect OFF, gain 1  //byte adcon_data = 0x01;   // 0 00 00 001 => Clock Out = Off, Sensor Detect OFF, gain 2  SPI.transfer(0x50 | adcon_reg);  // 52h = 0101 0010  SPI.transfer(0x00);              // 2nd command byte, write one register only  SPI.transfer(adcon_data);        // write the databyte to the register  delayMicroseconds(100);  byte drate_reg = 0x03; //DRATE: A/D Data Rate (Address 03h)  byte drate_data = 0xF0; // F0h = 11110000 = 30,000SPS  SPI.transfer(0x50 | drate_reg);  SPI.transfer(0x00);   // 2nd command byte, write one register only  SPI.transfer(drate_data);   // write the databyte to the register  delayMicroseconds(100);  SPI.transfer(0xF0);       delay(100);  digitalWrite(cs, HIGH);  SPI.endTransaction();}void loop(){unsigned long msec0 = millis();saveinarray();unsigned long msec1 = millis();//Serial.print   ("capture interval ");//Serial.println (msec1 - msec0);//Serial.println("Iteration completed");delay(10);}void test(){  unsigned long adc_val[1] = {0}; // store readings in array  byte mux[1] = {0x08};  int i = 0;  SPI.beginTransaction(SPISettings(SPISPEED, MSBFIRST, SPI_MODE1)); // start SPI  digitalWrite(cs, LOW);  delayMicroseconds(2);   for (i=0; i <1; i++){         // read all 8 Single Ended Channels AINx-AINCOM  byte channel = mux[i];             // analog in channels #  while (digitalRead(rdy)) {} ;                           SPI.transfer(0x50 | 0x01); // 1st Command Byte: 0101 0001  0001 = MUX register address 01h  SPI.transfer(0x00);     // 2nd Command Byte: 0000 0000  1-1=0 write one byte only  SPI.transfer(channel);     // Data Byte(s): xxxx 1000  write the databyte to the register(s)  delayMicroseconds(2);  //SYNC command 1111 1100                               // ********** Step 2 **********  SPI.transfer(0xFC);  delayMicroseconds(2);  SPI.transfer(0x00);  delayMicroseconds(250);   // Allow settling time  SPI.transfer(0x01); // Read Data 0000  0001 (01h)       // ********** Step 3 **********  delayMicroseconds(5);   adc_val[i] = SPI.transfer(0);  adc_val[i] <<= 8; //shift to left  adc_val[i] |= SPI.transfer(0);  adc_val[i] <<= 8;  adc_val[i] |= SPI.transfer(0);  delayMicroseconds(2);  }                                // Repeat for each channel ********** Step 4 **********   digitalWrite(cs, HIGH);  SPI.endTransaction();  //The ADS1255/6 output 24 bits of data in Binary Two's  //Complement format. The LSB has a weight of  //2VREF/(PGA(223 − 1)). A positive full-scale input produces  //an output code of 7FFFFFh and the negative full-scale  //input produces an output code of 800000h.  for (i=0; i <1; i++)  {   // Single ended Measurements  if(adc_val[i] > 0x7fffff)  {     adc_val[i] = adc_val[i]-16777216; //do 2's complement  }   float voltage = ((2*VREF) / 8388608)*adc_val[0];  float  Read_Data = adc_val[i] *0.0000002980232;value1 = adc_val[0] *0.0000002980232;value2 = adc_val[1] *0.0000002980232;value3 = adc_val[2] *0.0000002980232;x = (voltage - 0.5);//  Serial.print(Read_Data);   // Raw ADC integer value +/- 23 bits//  Serial.print("      ");//Serial.println(x);}}void saveinarray(){  for( i=0; i<SAMPLES1; i++)  {        test();    k[i]=x;    Serial.print("k[i] is :");    Serial.print("\t");    Serial.print(i);    Serial.print("\t");    Serial.println(k[i]);  }}