Can a component with a different current and voltage, to the circuit work?

Lets say i'm using a stepper motor with a voltage of 4.2V and a rated current of 2.8V to a microcontroller board with a switching supply of 5V/4A. Can the motor work?

I guess you meant a rated current of 2.8A?

The answer can be a YES or a NO. depending upon the minimum acceptable level of the microcontroller. If the minimum acceptable threshold is less than or equal to 4.2V/2.8A, it will accept it, but i think it won't. The min current level is very low in your case.

see , basically you cannot use the same source for both controller and stepper motor.

Reason being , micro controller are low power consuming non mobile units while stepper motor is a rotary device with mechanical movement and a supply of such high ratings will "FRY" YOUR CONTROLLER

So a general tendency is to use a low rating supply for the controller and then driving stepper motor using a "CURRENT DRIVER IC"

---------- Post added at 19:40 ---------- Previous post was at 19:39 ----------

see , basically you cannot use the same source for both controller and stepper motor.

Reason being , micro controller are low power consuming non mobile units while stepper motor is a rotary device with mechanical movement and a supply of such high ratings will "FRY" YOUR CONTROLLER

So a general tendency is to use a low rating supply for the controller and then driving stepper motor using a "CURRENT DRIVER IC"