Merge pull request #127 from sparkfun/eeprom-variable-size

add configurable EEPROM length

Author: Owen

Diff for: libraries/EEPROM/examples/Example2_AllFunctions/Example2_AllFunctions.ino

@@ -23,6 +23,12 @@
 
 void setup()
 {
+  // You may choose to enable more or less EEPROM -
+  // Default length is 1024 bytes (if setLength is not called)
+  EEPROM.setLength(1080); // this would make the length 1080 bytes
+  // EEPROM.setLength(AP3_EEPROM_MAX_LENGTH); // the maximum length is 8192 bytes (AP3_EEPROM_MAX_LENGTH)
+  // Note: larger sizes will increase RAM usage and execution time
+
   Serial.begin(115200);
   Serial.println("EEPROM Examples");
 
@@ -44,25 +50,25 @@ void setup()
   Serial.println("8 bit tests");
   byte myValue1 = 200;
   byte myValue2 = 23;
-  randomLocation = random(0, AP3_FLASH_EEPROM_SIZE);
+  randomLocation = random(0, EEPROM.length() - sizeof(myValue1));
 
   startTime = millis();
   EEPROM.write(randomLocation, myValue1); //(location, data)
   endTime = millis();
-  EEPROM.put(randomLocation + 1, myValue2);
+  EEPROM.put(randomLocation + sizeof(myValue1), myValue2);
 
   Serial.printf("Write byte time: %dms\n", endTime - startTime);
 
   startTime = millis();
   EEPROM.write(randomLocation, myValue1); //(location, data)
   endTime = millis();
 
-  Serial.printf("Write identical byte to same location (should be ~1): %dms\n", endTime - startTime);
+  Serial.printf("Write identical byte to same location: %dms\n", endTime - startTime);
 
   byte response1 = EEPROM.read(randomLocation);
-  byte response2 = EEPROM.read(randomLocation + 1);
+  byte response2 = EEPROM.read(randomLocation + sizeof(myValue1));
   Serial.printf("Location %d should be %d: %d\n\r", randomLocation, myValue1, response1);
-  Serial.printf("Location %d should be %d: %d\n\r", randomLocation + 1, myValue2, response2);
+  Serial.printf("Location %d should be %d: %d\n\r", randomLocation + sizeof(myValue1), myValue2, response2);
   //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
 
   Serial.println("");
@@ -72,17 +78,17 @@ void setup()
   //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
   uint16_t myValue3 = 3411;
   int16_t myValue4 = -366;
-  randomLocation = random(0, AP3_FLASH_EEPROM_SIZE);
+  randomLocation = random(0, EEPROM.length() - sizeof(myValue3));
 
   EEPROM.put(randomLocation, myValue3);
-  EEPROM.put(randomLocation + 2, myValue4);
+  EEPROM.put(randomLocation + sizeof(myValue3), myValue4);
 
   uint16_t response3;
   int16_t response4;
   EEPROM.get(randomLocation, response3);
-  EEPROM.get(randomLocation + 2, response4);
+  EEPROM.get(randomLocation + sizeof(myValue3), response4);
   Serial.printf("Location %d should be %d: %d\n\r", randomLocation, myValue3, response3);
-  Serial.printf("Location %d should be %d: %d\n\r", randomLocation + 2, myValue4, response4);
+  Serial.printf("Location %d should be %d: %d\n\r", randomLocation + sizeof(myValue3), myValue4, response4);
   //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
 
   Serial.println("");
@@ -93,52 +99,52 @@ void setup()
   Serial.printf("Size of int: %d\n", sizeof(int));
   int myValue5 = -245000;
   unsigned int myValue6 = 400123;
-  randomLocation = random(0, AP3_FLASH_EEPROM_SIZE);
+  randomLocation = random(0, EEPROM.length() - sizeof(myValue5));
 
   EEPROM.put(randomLocation, myValue5);
-  EEPROM.put(randomLocation + 4, myValue6);
+  EEPROM.put(randomLocation + sizeof(myValue5), myValue6);
 
   int response5;
   unsigned int response6;
   EEPROM.get(randomLocation, response5);
-  EEPROM.get(randomLocation + 4, response6);
+  EEPROM.get(randomLocation + sizeof(myValue5), response6);
   Serial.printf("Location %d should be %d: %d\n\r", randomLocation, myValue5, response5);
-  Serial.printf("Location %d should be %d: %d\n\r", randomLocation + 4, myValue6, response6);
+  Serial.printf("Location %d should be %d: %d\n\r", randomLocation + sizeof(myValue5), myValue6, response6);
   //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
 
   //int32_t and uint32_t sequential test
   //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
   int32_t myValue7 = -341002;
   uint32_t myValue8 = 241544;
-  randomLocation = random(0, AP3_FLASH_EEPROM_SIZE);
+  randomLocation = random(0, EEPROM.length() - sizeof(myValue7));
 
   EEPROM.put(randomLocation, myValue7);
-  EEPROM.put(randomLocation + 4, myValue8);
+  EEPROM.put(randomLocation + sizeof(myValue7), myValue8);
 
   int32_t response7;
   uint32_t response8;
   EEPROM.get(randomLocation, response7);
-  EEPROM.get(randomLocation + 4, response8);
+  EEPROM.get(randomLocation + sizeof(myValue7), response8);
   Serial.printf("Location %d should be %d: %d\n\r", randomLocation, myValue7, response7);
-  Serial.printf("Location %d should be %d: %d\n\r", randomLocation + 4, myValue8, response8);
+  Serial.printf("Location %d should be %d: %d\n\r", randomLocation + sizeof(myValue7), myValue8, response8);
   //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
 
   //float (32) sequential test
   //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
   Serial.printf("Size of float: %d\n", sizeof(float));
   float myValue9 = -7.35;
   float myValue10 = 5.22;
-  randomLocation = random(0, AP3_FLASH_EEPROM_SIZE);
+  randomLocation = random(0, EEPROM.length() - sizeof(myValue9));
 
   EEPROM.put(randomLocation, myValue9);
-  EEPROM.put(randomLocation + 4, myValue10);
+  EEPROM.put(randomLocation + sizeof(myValue9), myValue10);
 
   float response9;
   float response10;
   EEPROM.get(randomLocation, response9);
-  EEPROM.get(randomLocation + 4, response10);
+  EEPROM.get(randomLocation + sizeof(myValue9), response10);
   Serial.printf("Location %d should be %f: %f\n\r", randomLocation, myValue9, response9);
-  Serial.printf("Location %d should be %f: %f\n\r", randomLocation + 4, myValue10, response10);
+  Serial.printf("Location %d should be %f: %f\n\r", randomLocation + sizeof(myValue9), myValue10, response10);
   //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
 
   Serial.println("");
@@ -151,24 +157,24 @@ void setup()
   double myValue12 = 384.95734987;
   double myValue13 = 917.14159;
   double myValue14 = 254.8877;
-  randomLocation = random(0, AP3_FLASH_EEPROM_SIZE);
+  randomLocation = random(0, EEPROM.length() - sizeof(myValue11));
 
   startTime = millis();
   EEPROM.put(randomLocation, myValue11);
   endTime = millis();
   Serial.printf("Time to record 64-bits: %dms\n", endTime - startTime);
 
-  EEPROM.put(randomLocation + 8, myValue12);
+  EEPROM.put(randomLocation + sizeof(myValue11), myValue12);
   EEPROM.put(EEPROM.length() - sizeof(myValue13), myValue13); //Test end of EEPROM space
 
   double response11;
   double response12;
   double response13;
   EEPROM.get(randomLocation, response11);
-  EEPROM.get(randomLocation + 8, response12);
+  EEPROM.get(randomLocation + sizeof(myValue11), response12);
   EEPROM.get(EEPROM.length() - sizeof(myValue13), response13);
   Serial.printf("Location %d should be %lf: %lf\n", randomLocation, myValue11, response11);
-  Serial.printf("Location %d should be %lf: %lf\n", randomLocation + 8, myValue12, response12);
+  Serial.printf("Location %d should be %lf: %lf\n", randomLocation + sizeof(myValue11), myValue12, response12);
   Serial.printf("Edge of EEPROM %d should be %lf: %lf\n", EEPROM.length() - sizeof(myValue13), myValue13, response13);
 
   double response14;
@@ -183,7 +189,7 @@ void setup()
   //String write test
   //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
   char myString[19] = "How are you today?";
-  randomLocation = random(0, AP3_FLASH_EEPROM_SIZE);
+  randomLocation = random(0, EEPROM.length() - sizeof(myString));
   EEPROM.put(randomLocation, myString);
 
   char readMy[19];

Diff for: libraries/EEPROM/src/EEPROM.cpp

@@ -40,10 +40,12 @@
 #include "EEPROM.h"
 #include "Arduino.h"
 
+EEPROMClass EEPROM; // the (magnificent) one and only EEPROM!!!!!
+
 //Write a byte to a given "EEPROM" location
-void write(uint16_t eepromLocation, uint8_t dataToWrite)
+void write(uint16_t eepromLocation, uint8_t dataToWrite, uint16_t allowedSize)
 {
-  writeBlockToEEPROM(eepromLocation, &dataToWrite, 1);
+  writeBlockToEEPROM(eepromLocation, &dataToWrite, 1, allowedSize);
 }
 
 //Read a byte from a given location in "EEPROM"
@@ -66,23 +68,23 @@ void EEPROMClass::erase()
 //3) Check if new data is different from flash.
 //4) Erase flash page (8k)
 //5) Write SRAM back into flash
-void writeBlockToEEPROM(uint16_t eepromLocation, const uint8_t *dataToWrite, uint16_t blockSize)
+void writeBlockToEEPROM(uint16_t eepromLocation, const uint8_t *dataToWrite, uint16_t blockSize, uint16_t allowedSize)
 {
   //Error check
-  if (eepromLocation + blockSize >= AP3_FLASH_EEPROM_SIZE)
+  if (eepromLocation + blockSize >= allowedSize)
   {
-    blockSize = AP3_FLASH_EEPROM_SIZE - eepromLocation;
+    blockSize = allowedSize - eepromLocation;
   }
 
   //Read the contents of current "EEPROM" to SRAM
   //Flash is written in 32-bit words but user passes in array of bytes
   //Create an array of 32-bit words but reference it a byte at a time
-  uint32_t flashContent[AP3_FLASH_EEPROM_SIZE / 4];
+  uint32_t flashContent[allowedSize / 4];
 
   //We can't read 32bits at a time because the way flash is oriented (little endian)
   //So we read a byte at a time
   uint8_t *eepromContents = (uint8_t *)flashContent;
-  for (uint16_t x = 0; x < AP3_FLASH_EEPROM_SIZE; x++)
+  for (uint16_t x = 0; x < allowedSize; x++)
   {
     eepromContents[x] = *(uint8_t *)(AP3_FLASH_EEPROM_START + x);
   }
@@ -96,7 +98,7 @@ void writeBlockToEEPROM(uint16_t eepromLocation, const uint8_t *dataToWrite, uin
   //Run a check here to see if the new data is the same as what's in flash. If it's the same,
   //just return, don't erase flash.
   bool theSame = true;
-  for (uint16_t x = 0; x < AP3_FLASH_EEPROM_SIZE; x++)
+  for (uint16_t x = 0; x < allowedSize; x++)
   {
     if (eepromContents[x] != *(uint8_t *)(AP3_FLASH_EEPROM_START + x))
     {
@@ -116,5 +118,10 @@ void writeBlockToEEPROM(uint16_t eepromLocation, const uint8_t *dataToWrite, uin
   am_hal_flash_program_main(AM_HAL_FLASH_PROGRAM_KEY,
                             flashContent,
                             (uint32_t *)AP3_FLASH_EEPROM_START,
-                            AP3_FLASH_EEPROM_SIZE / 4);
+                            allowedSize / 4);
 }
+
+EERef &EERef::operator=(uint8_t in)
+{
+  return write(index, in, EEPROM.length()), *this;
+}

Diff for: libraries/EEPROM/src/EEPROM.h

@@ -59,21 +59,29 @@
 //The SparkFun Apollo3 linker script has been modified to limit user code space to less than 0xFE000
 
 #define AP3_FLASH_EEPROM_START 0xFE000
+#define AP3_FLASH_PAGE_SIZE 8192
+#define AP3_EEPROM_MAX_LENGTH (AP3_FLASH_PAGE_SIZE - 16)
 
-#if AP3_FLASH_EEPROM_START % 8192
+#if AP3_FLASH_EEPROM_START % AP3_FLASH_PAGE_SIZE
 Error : EEPROM start address must be divisble by 8192
 #endif
 
-        //By limiting EEPROM size to 1024 bytes, we reduce the amount of SRAM required and
-        //time needed to read/write words into flash. It can be increased
-        //to 2048 if needed
+        //The size of the EEPROM may be (optionally) user-configured using the EEPROM.setLength()
+        //method. Valid values are in the range [0, AP3_EEPROM_MAX_LENGTH]. Reducing the size of
+        //EEPROM will cause data stored in the higher addresses to be lost. The default size is
+        //set below. See Example2_AllFunctions for a usage example.
+
+        //Operations on psuedo-EEPROM require a read-write-modify cycle on the entire
+        //configured memory area because flash pages cannot be partially erased. The
+        //larger the memory area the longer this operation will take. Here are some
+        //benchmarks:
         //1024 = 19ms update time
         //2048 = 23ms update time
-        const int AP3_FLASH_EEPROM_SIZE = 1024; //In bytes
+        const uint16_t AP3_DEFAULT_FLASH_EEPROM_SIZE = 1024; //In bytes
 
 uint8_t read(uint16_t eepromLocation);
-void write(uint16_t eepromLocation, uint8_t dataToWrite);
-void writeBlockToEEPROM(uint16_t eepromLocation, const uint8_t *dataToWrite, uint16_t blockSize);
+void write(uint16_t eepromLocation, uint8_t dataToWrite, uint16_t allowedSize);
+void writeBlockToEEPROM(uint16_t eepromLocation, const uint8_t *dataToWrite, uint16_t blockSize, uint16_t allowedSize);
 
 struct EERef
 {
@@ -86,7 +94,7 @@ struct EERef
 
   //Assignment/write members.
   EERef &operator=(const EERef &ref) { return *this = *ref; }
-  EERef &operator=(uint8_t in) { return write(index, in), *this; }
+  EERef &operator=(uint8_t in);
   EERef &operator+=(uint8_t in) { return *this = **this + in; }
   EERef &operator-=(uint8_t in) { return *this = **this - in; }
   EERef &operator*=(uint8_t in) { return *this = **this * in; }
@@ -163,7 +171,10 @@ struct EEPROMClass
   //Basic user access methods.
   EERef operator[](const int idx) { return idx; }
   uint8_t read(int idx) { return EERef(idx); }
-  void write(int idx, uint8_t val) { (EERef(idx)) = val; }
+  void write(int idx, uint8_t val)
+  {
+    (EERef(idx)) = val;
+  }
   void update(int idx, uint8_t val) { EERef(idx).update(val); }
   void erase();
 
@@ -174,7 +185,14 @@ struct EEPROMClass
     return 0x00;
   }
   EEPtr end() { return length(); } //Standards requires this to be the item after the last valid entry. The returned pointer is invalid.
-  uint16_t length() { return AP3_FLASH_EEPROM_SIZE; }
+  uint16_t length()
+  {
+    return allowedSize;
+  }
+  void setLength(uint16_t length)
+  {
+    allowedSize = (length <= AP3_EEPROM_MAX_LENGTH) ? length : AP3_EEPROM_MAX_LENGTH;
+  }
 
   //Functionality to 'get' and 'put' objects to and from EEPROM.
   template <typename T>
@@ -192,11 +210,13 @@ struct EEPROMClass
   {
     const uint8_t *ptr = (const uint8_t *)&t;
 
-    writeBlockToEEPROM(idx, ptr, sizeof(T)); //Address, data, sizeOfData
+    writeBlockToEEPROM(idx, ptr, sizeof(T), allowedSize); //Address, data, sizeOfData
 
     return t;
   }
+
+  uint16_t allowedSize = AP3_DEFAULT_FLASH_EEPROM_SIZE;
 };
 
-static EEPROMClass EEPROM __attribute__((unused));
+extern EEPROMClass EEPROM;
 #endif //_EEPROM_H