Create read-write-to-EEPROM.ino

Reading-Writing-to-EEPROM/read-writer-to-eeprom.ino

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+#include <EEPROM.h>
+
+void setup() {
+  Serial.begin(9600);
+  EEPROM.begin(32);  //Syntax: EEPROM.begin(Size)
+  // You need to call EEPROM.begin(size) before you can start reading or writing, where the size parameter is the number of bytes you want to use store
+  // Size can be anywhere between a minimum of 4 and maximum of 4096 bytes.
+}
+
+void loop() {
+  // 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 // 32-bytes of random data
+  // EEPROM.put(eeAddress, variable_name);    // Writes a variable type e.g. float = 4-bytes, int = 4-bytes, boolean = 1 byte
+  // EEPROM.get(eeAddress, variable_name);    // Reads a variable type  e.g. float = 4-bytes, int = 4-bytes, boolean = 1 byte
+  // int value = EEPROM.read(eeAddress);      // Read a single byte
+  // EEPROM.write(eeAddress, variable_name);  // Write a single byte
+  // EEEPROM.commit() commands such as EEPROM.write or EEPROM.put do not write to flash immediately, to invoke them you must call EEPROM.commit() to save changes to flash/EEPROM
+  // EEPROM.end() will also commit, but releases the RAM copy of EEPROM contents.
+
+  // Commands to determine variable sizes, needed for storing to EEPROM
+  Serial.println("            Floating point variables need: "+String(sizeof(float))+" Bytes");  // Determine how many bytes (4) are needed to save a floating point variable
+  Serial.println("Double size floating point variables need: "+String(sizeof(double))+ " Bytes"); // Determine how many bytes (8) are needed to save a floating point variable
+  Serial.println("                   Integer variables need: "+String(sizeof(int))+" Bytes");    // Determine how many bytes (4) are needed to save an integer variable
+  Serial.println("         Boolean values or variables need: "+String(sizeof(bool))+" Bytes");   // Determine how many bytes (1) are needed to save a boolean variable
+  Serial.println("           String variables need at least: "+String(sizeof(String))+" Bytes"); // Determine how many bytes (min. 12) are needed to save a string variable
+  Serial.println();
+
+  //----------------------------------------------------------------------------  
+  // Example-1 Write a value to EEPROM at address = 0
+  int EEaddress = 0;
+  EEPROM.write(EEaddress,123); // Writes the value 123 to EEPROM
+  // 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 // Contents of EEPROM
+  // 7B 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 // Contents of RAM copy of EEPROM
+  EEPROM.commit();
+  // 7B 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 // Contents of EEPROM
+  Serial.print("EEPROM contents at Address=0 is  : ");
+  Serial.println(EEPROM.read(EEaddress));
+
+  //----------------------------------------------------------------------------  
+  // Example-2 Write a value to EEPROM at address = 0
+  // 7B 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 // Contents of EEPROM
+  EEPROM.write(EEaddress,257); // Writes the value 257 to EEPROM
+  EEPROM.commit();
+  // 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 // Contents of EEPROM
+  Serial.print("EEPROM contents at Address=0 is  : ");
+  Serial.println(EEPROM.read(EEaddress));
+
+  //----------------------------------------------------------------------------  
+  // Example-3 Write an integer variable to EEPROM at address = 0
+  int integer_variable = 257;
+  // 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 // Contents of EEPROM
+  EEPROM.put(EEaddress,integer_variable); // Writes the value 257 to EEPROM
+  EEPROM.commit();
+  // 01 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 // Contents of EEPROM
+  Serial.print("EEPROM contents at Address=0 is  : ");
+  integer_variable = 0; // To prove it read from EEPROM!
+  EEPROM.get(EEaddress,integer_variable);
+  Serial.println(integer_variable);
+
+  //----------------------------------------------------------------------------  
+  // Example-4 Write another integer variable to EEPROM
+  int integer_variable2 = 1234;
+  // 01 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 // Contents of EEPROM
+  EEaddress = EEaddress + sizeof(int); // Moves the address along by 4
+  EEPROM.put(EEaddress,integer_variable2); // Writes the value 1234 to EEPROM
+  EEPROM.commit();
+  // 01 01 00 00 D2 04 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 // Contents of EEPROM
+  Serial.print("EEPROM contents at Address=4 is  : ");
+  integer_variable2 = 0; // To prove it read from EEPROM!
+  EEPROM.get(EEaddress,integer_variable2);
+  Serial.println(integer_variable2);
+  EEaddress = EEaddress + sizeof(int); // Moves the address along by 4
+
+  //----------------------------------------------------------------------------  
+  // Example-5 Write a floating point variable to EEPROM
+  float floatingpoint_variable = 3.141592654;
+  EEPROM.put(EEaddress,floatingpoint_variable); // Writes the value 3.141592654 to EEPROM
+  EEPROM.commit();
+  Serial.print("EEPROM contents at Address=8 is  : ");
+  floatingpoint_variable = 0; // To prove it read from EEPROM!
+  EEPROM.get(EEaddress,floatingpoint_variable);
+  Serial.println(floatingpoint_variable,8);
+  EEaddress = EEaddress + sizeof(float);        // Moves the address along by 4
+
+  //----------------------------------------------------------------------------  
+  // Example-6 Write a string variable to EEPROM
+  String string_variable = "Hello world";
+  EEPROM.put(EEaddress,string_variable); // Writes the value 3.141592654 to EEPROM
+  EEPROM.commit();
+  Serial.print("EEPROM contents at Address=12 is : ");
+  floatingpoint_variable = 0; // To prove it read from EEPROM!
+  EEPROM.get(EEaddress,string_variable);
+  Serial.println(string_variable);
+  EEaddress = EEaddress + sizeof(string_variable);        // Moves the address along by 4
+
+  //----------------------------------------------------------------------------  
+  // Example-7 Write a series of values to EEPROM
+  for (int i = 1000; i <= 1032; i = i + 4) {
+    EEPROM.put(i-1000,i); // Address range 0-32
+  }
+  EEPROM.commit();
+  for (int j = 1000; j <= 1032; j = j + 4) {
+    EEPROM.get((j-1000),integer_variable); // Read the 32 values
+    Serial.println(integer_variable);
+  }
+
+  //----------------------------------------------------------------------------  
+  // Example-8 Testing that the EEPROM extent has not been exceeded, remember not to exceed address space
+  if (EEaddress == 32) {
+    EEaddress = 0;
+  }
+
+  //----------------------------------------------------------------------------  
+  // Example-9 Compact method of writing and reading values from EEPROM
+  EEaddress = 20;
+  // Writing
+  floatingpoint_variable = 2 * PI;
+  EEaddress += EEPROM.put(EEaddress, floatingpoint_variable);
+  integer_variable = 123456789;
+  EEaddress += EEPROM.put(EEaddress, integer_variable);
+  EEPROM.end();
+
+  EEaddress = 20;
+  // Reading
+  EEaddress += EEPROM.get(EEaddress, floatingpoint_variable);
+  EEaddress += EEPROM.get(EEaddress, integer_variable);
+  EEPROM.commit();
+  Serial.println(floatingpoint_variable,7);
+  Serial.println(integer_variable);
+
+  delay(10000);
+}
+