Updated EEPROM examples.

Removed hard coded lengths, which were incorrect for standard Arduino's
now.

1 files changed, 20 insertions, 3 deletions

diff --git a/libraries/EEPROM/examples/eeprom_update/eeprom_update.ino b/libraries/EEPROM/examples/eeprom_update/eeprom_update.ino
index e0e18d8..dbf05ec 100644
--- a/libraries/EEPROM/examples/eeprom_update/eeprom_update.ino
+++ b/libraries/EEPROM/examples/eeprom_update/eeprom_update.ino
@@ -38,15 +38,32 @@ void loop()
     The function EEPROM.update(addr, val) is equivalent to the following:
   
     if( EEPROM.read(addr) != val ){
-	  EEPROM.write(addr, val);
+      EEPROM.write(addr, val);
     }
   ***/
   
 
-  /** advance to the next address.  there are 512 bytes in the EEPROM, so go back to 0 when we hit 512. **/
+  /***
+    Advance to the next address, when at the end restart at the beginning.    
+    
+    Larger AVR processors have larger EEPROM sizes, E.g:
+    - Arduno Duemilanove: 512b EEPROM storage.
+    - Arduino Uno:        1kb EEPROM storage.
+    - Arduino Mega:       4kb EEPROM storage.
+    
+    Rather than hard-coding the length, you should use the pre-provided length function.
+    This will make your code portable to all AVR processors.    
+  ***/
   addr = addr + 1;
-  if (addr == 512)
+  if(addr == EEPROM.length())
     addr = 0;
+    
+  /***
+    As the EEPROM sizes are powers of two, wrapping (preventing overflow) of an 
+    EEPROM address is also doable by a bitwise and of the length - 1.
+    
+    ++addr &= EEPROM.length() - 1;
+  ***/
 
   delay(100);
 }