Hi ! How to interface(soft ware wise) MAX1232 to at89c2051?
Thanks in advance, nag
Have you read the datasheet for the MAX1232?
It contains _very clear_ instructions how to connect the chip electrically, and how to interact with it in software.
All you need to do, is learn how to toggle a digital output for the watchdog (brownout level and watchdog timeout length is normally hard-coded by holding the pins high or low), and then make sure that you perform the port toggling often enough.