add eeprom library explicitly

digistump-avr/libraries/EEPROM/examples/eeprom_write/eeprom_write.ino

@@ -0,0 +1,58 @@
+/*
+ * EEPROM Write
+ *
+ * Stores values read from analog input 0 into the EEPROM.
+ * These values will stay in the EEPROM when the board is
+ * turned off and may be retrieved later by another sketch.
+ */
+
+#include <EEPROM.h>
+
+/** the current address in the EEPROM (i.e. which byte we're going to write to next) **/
+int addr = 0; 
+
+void setup(){ /** Empty setup. **/}
+
+void loop()
+{
+  /***
+    Need to divide by 4 because analog inputs range from
+    0 to 1023 and each byte of the EEPROM can only hold a
+    value from 0 to 255.
+  ***/
+  
+  int val = analogRead(0) / 4;
+
+  /***
+    Write the value to the appropriate byte of the EEPROM.
+    these values will remain there when the board is
+    turned off.
+  ***/
+  
+  EEPROM.write(addr, val);
+
+  /***
+    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 == 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);
+}