Dear Babar,

How r u doing?

I could not understand the circuit as it shows so many descrete pieces, but if you can workout code for PWM (Pulse Width Modulation) you can control the ultimate voltage across LED or any thing else, by simply controlling duty cycle of high-time.

I already developed the code for one of such application and tried, it works fine.

Please let me know if this could be of some use for you, I will send you the code if you wish.

Thanks and best regards,

Rauf / Microlink-Dubai