24LC256 I2C EEPROM 256kbit

• Make sure write enabled is on. (connected to GND)
• Use pull ups on i2c or it will not work.
• Default address is 0x50
• https://www.microchip.com/wwwproducts/en/24LC256
• http://ww1.microchip.com/downloads/en/DeviceDoc/24AA256-24LC256-24FC256-Data-Sheet-20001203V.pdf
• 32K bytes usable space.
• Writes are much faster a page at a time, about 5 seconds to write the entire 32Kb.

void writeEEPROMPage(int deviceaddress, unsigned int eeaddress, int *data ) {
  Wire.beginTransmission(deviceaddress);
  Wire.write((uint8_t)(eeaddress >> 8));    // MSB 
  Wire.write((uint8_t)(eeaddress & 0xFF)); // LSB 
 
  for (int i=0;i<64;i++){
    Wire.write(data[i]);
  }
  Wire.endTransmission();
  delay(10);
}
 
void writeEEPROM(int deviceaddress, unsigned int eeaddress, int data ) 
{
  Wire.beginTransmission(deviceaddress);
  Wire.write((uint8_t)(eeaddress >> 8));    // MSB 
  Wire.write((uint8_t)(eeaddress & 0xFF)); // LSB 
  Wire.write(data);
  Wire.endTransmission();
  delay(10);
}
 
uint8_t readEEPROM(int deviceaddress, unsigned int  eeaddress ) 
{
  uint8_t rdata = 0x00;
 
  Wire.beginTransmission(deviceaddress);
  Wire.write((uint8_t)(eeaddress >> 8));    // MSB 
  Wire.write((uint8_t)(eeaddress & 0xFF)); // LSB 
  Wire.endTransmission();
  Wire.requestFrom(deviceaddress, 1);
 
  while (Wire.available()){
    rdata = Wire.read();
  }
 
  return rdata;
}