spartan 3an control unipolar stepper motor

HI.
I work for my thesis on a sun tracking algorithm. i use two unipolar stepper motors for moving the solar panel on two axis' . i have a problem with the pulses to move motors . Does anyone know where i can find any vhdl examples ?

Check these
Stepper Motor Controller :: Overview :: OpenCores
www.actel.com/documents/StepMotorController_AN.pdf

u just need to find/write the PWM modulator

Thanks for your help. I have some questions. I have made the driver modules for my two stepper motors. Now i have to program my spartan 3an . What i want is to to take an analog signal (voltage) from pv panel and check my algo which controls the movement of motors . I have googled it but i can t understand what procedure i have to follow.
So: First use amp-adc to get my digital signal .Then by checking voltage value, control stepper motors with pwm generator . Is that right?Do i have to use something more ? I make look silly asking something like that but i have read so much about that , that i can t understand what i finally want . Do i have to use the picoblaze processor or is it something more simple like downloading a program where u turn on/off leds using switches? help me.thank u in advance