diff --git a/Marlin/src/HAL/shared/eeprom_if_i2c.cpp b/Marlin/src/HAL/shared/eeprom_if_i2c.cpp index 27f0233562..6b559e234b 100644 --- a/Marlin/src/HAL/shared/eeprom_if_i2c.cpp +++ b/Marlin/src/HAL/shared/eeprom_if_i2c.cpp @@ -61,11 +61,24 @@ static constexpr uint8_t eeprom_device_address = I2C_ADDRESS(EEPROM_DEVICE_ADDRE // Public functions // ------------------------ +#define SMALL_EEPROM (MARLIN_EEPROM_SIZE <= 2048) + +// Combine Address high bits into the device address on <=16Kbit (2K) and >512Kbit (64K) EEPROMs. +// Note: MARLIN_EEPROM_SIZE is specified in bytes, whereas EEPROM model numbers refer to bits. +// e.g., The "16" in BL24C16 indicates a 16Kbit (2KB) size. +static uint8_t _eeprom_calc_device_address(uint8_t * const pos) { + const unsigned eeprom_address = (unsigned)pos; + return (SMALL_EEPROM || MARLIN_EEPROM_SIZE > 65536) + ? uint8_t(eeprom_device_address | ((eeprom_address >> (SMALL_EEPROM ? 8 : 16)) & 0x07)) + : eeprom_device_address; +} + static void _eeprom_begin(uint8_t * const pos) { const unsigned eeprom_address = (unsigned)pos; - Wire.beginTransmission(eeprom_device_address); - Wire.write(int(eeprom_address >> 8)); // Address High - Wire.write(int(eeprom_address & 0xFF)); // Address Low + Wire.beginTransmission(_eeprom_calc_device_address(pos)); + if (!SMALL_EEPROM) + Wire.write(uint8_t((eeprom_address >> 8) & 0xFF)); // Address High, if needed + Wire.write(uint8_t(eeprom_address & 0xFF)); // Address Low } void eeprom_write_byte(uint8_t *pos, uint8_t value) { @@ -81,7 +94,7 @@ void eeprom_write_byte(uint8_t *pos, uint8_t value) { uint8_t eeprom_read_byte(uint8_t *pos) { _eeprom_begin(pos); Wire.endTransmission(); - Wire.requestFrom(eeprom_device_address, (byte)1); + Wire.requestFrom(_eeprom_calc_device_address(pos), (byte)1); return Wire.available() ? Wire.read() : 0xFF; }