Hi Azhar,

I agree with Steve that it's overkill to use a uC to do this. Visit the Power Integrations website. They have a range of cheap, easy to use dedicated switcher IC's with internal transistor, overcurrent and overtemperature protection, etc. They also have a design guide, design software and application notes which will make transformer calculations really easy.

Anything else you should know? Please be very, very careful! You are working with potentially lethal voltages.

Stay safe,
Rob.