atmel 89c5131 require help

hi i have been assigned on a project by my teacher on making the LED dim by using this following chip and no other chips in my current testing board

may i know can it be done? i read the chip data sheet and found out it don hav pwm & adc... so is there any way to do it? plz enlighten me thx

Check this

**broken link removed**

Hope this will help..