Dear Friends,

Thanx for so many suggestions.

While I made some debugging yesterday (i.e. Friday, 31st oct) after my Diwali Vacations from Tuesday to Thursday.

As said in my original post I have a program that uses P89c669 & communicates with at24c16.
I combined both boards using 4 wires, viz SCL, SDA, GND, VCC.

Both MCU has there own individual LCD & Keypad(4x4). What they share is supply & I2C bus.

Now I did following things
1a. first I accessed EEPROM using 669 & write my name at a known location (48)(write initiated on key action).
1b. Now I read same location using 668 (read initiated on key action)

LCD corresponding to 668 MCU displays my name. It means 669 has written it correctly & 668 reads it correctly.

2a. Now I write company's name on same location using 668(triggered through key action)
2b. This value is now read using 669. It reads my name instead of company's name. (again reading using 668 also reads my name only)


Then before writing to EEPROM using 668, I sent the data, its length & address on UART. This string when captured using HyperTerminal seems fine.

Conclusion:
It means I am able to read from at24c16 using 668, but write is not working due to (so far) unknown reason.

Mystery is the same write routines works with DS1307. Also I am writing only once hence EEPROM being busy cant be an issue.

Regards,
Mahesh