i dont know what is Easy Driver stepper motor driver board. how it works how it functions. u can build simple stepper motor driver using IC555 and johnson counter and ULN2003A current driver chip that gives pulses in sequences to stepper motor to rotate it. the speed of motor can be changed by changing frequency of applied pulses from IC555. you can not apply more pulses then max RPM of your motor.
like if max RPM of motor is 6000 then you can not give more than 6000/60 = 100 pulses per second