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ArduinoISP.ino does not properly handle word-based address for EEPROM read/write #2186

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#2188
Open
ArduinoISP.ino does not properly handle word-based address for EEPROM read/write#2186
#2188
@x0urc3

Description

@x0urc3
x0urc3
opened on Jun 14, 2022

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;
}

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