pic16f877a_eepromWrite.c

void EEPROM_WriteByte(unsigned char eepromAddress, unsigned char eepromData)
{
    unsigned char gie_Status;
    
    while(WR);            // check the WR bit to see if a previous Write operation is in progress
    EEADR=eepromAddress;  // Write the address to EEADR.
    EEDATA=eepromData;    // load the 8-bit data value to be written in the EEDATA register.
    WREN=1;               // Set the WREN bit to enable eeprom operation.
    gie_Status = GIE;     // Copy the current Interrupt state
    GIE = 0;              // Disable the interrupts
    EECON2=0x55;          // Execute the special instruction sequence
    EECON2=0xaa;          // Refer the datasheet for more info
    WR=1;                 // Set the WR bit to trigger the eeprom write operation.
    GIE = gie_Status;     // Restore the interrupts
    WREN=0;               // Disable the EepromWrite
}