ArduinoISP.ino does not properly handle word-based address for EEPROM read/write

[Khairulmizam Samsudin]

Steps to reproduce
Reading and writing EEPROM using Adafruit ArduinoISP.ino will cause Bad EEPROM data. The official Arduino ArduinoISP.ino does not have similar issue. See avrdudes/avrdude/issues/990

Possible solution
The read and write EEPROM function does not handle word-based address. The high address byte is 0x00 in both function.

Adafruit_Learning_System_Guides/ArduinoISP/ArduinoISP/ArduinoISP.ino

Lines 550 to 557 in 0090edd

 char eeprom_read_page(int length) { 
   // here again we have a word address 
   for (int x = 0; x < length; x++) { 
     byte ee = spi_transaction(0xA0, 0x00, _addr*2+x, 0xFF); 
     Serial.write( ee); 
   } 
   return STK_OK; 
 } 

Adafruit_Learning_System_Guides/ArduinoISP/ArduinoISP/ArduinoISP.ino

Lines 487 to 496 in 0090edd

 byte write_eeprom(int length) { 
   // here is a word address, so we use here*2 
   // this writes byte-by-byte, 
   // page writing may be faster (4 bytes at a time) 
   for (int x = 0; x < length; x++) { 
     spi_transaction(0xC0, 0x00, _addr*2+x, buff[x]); 
     delay(45); 
   }  
   return STK_OK; 
 } 

[Anne Barela]

Please submit a pull request if at all possible.

[mcuee]

FYI, Arduino's example has the fix back in Dec 2011.
arduino/arduino-examples@ea98fc8

Specific fix here.
rsbohn/ArduinoISP@bc480b0