battery voltage for micro and motor

hi,

I'm using a microcontroller circuit to control step motor. My circuit needs only 5V, my motor needs 12V, and I'm using battery to for the whole system. So my battery should provide 12V, and I have to get 5V out of 12V for my control circuit.
So how do I do that? Can a simple voltage divider using resistors work?

Use a simple voltage regulator, such as an 7805.

Resistor voltage dividers are great for theoretical and low current usage.
You need a more stable supply. The 78L05 voltage regulator is a single transistor sized device and will allow up to 100mA or .5A )depending on the type...)
It only needs a few extra components to operate.

thanks a lot.

Do note that if you experience instabilities or random resets on your microcontroller, it could be because your motor is overstressing your power source on its current requirements.