SD Card Module

#include <SD.h>//Set by default for the SD Card Library//MOSI = Pin 11//MISO = Pin 12//SCLK = PIN 13//We always need to set the CS Pinint CS_pin = 10;int pow_pin = 8;float refresh_rate = 0.0;void setup(){  Serial.begin(9600);  Serial.println("Initializing Card");  //CS Pin is an output  pinMode(CS_pin, OUTPUT);  //Card will Draw Power from Pin 8, so set it high  pinMode(pow_pin, OUTPUT);  digitalWrite(pow_pin, HIGH);  if (!SD.begin(CS_pin))  {      Serial.println("Card Failure");      return;  }  Serial.println("Card Ready");  //Read the Configuration information (COMMANDS.txt)  File commandFile = SD.open("COMMANDS.txt");  if (commandFile)  {    Serial.println("Reading Command File");    float decade = pow(10, (commandFile.available() - 1));    while(commandFile.available())    {      float temp = (commandFile.read() - '0');      refresh_rate = temp*decade+refresh_rate;      decade = decade/10;    }    Serial.print("Refresh Rate = ");    Serial.print(refresh_rate);    Serial.println("ms");  }  else  {    Serial.println("Could not read command file.");    return;  }}void loop(){  String dataString = "Hello";  //Open a file to write to  //Only one file can be open at a time  File logFile = SD.open("LOG.txt", FILE_WRITE);  if (logFile)  {    logFile.println(dataString);    logFile.close();    Serial.println(dataString);  }  else  {Serial.println("LOG.txt");Serial.println("Couldn't open log file");  }  delay(refresh_rate);}