A standard bipolar stepper-motor usually will have 1.8 degree steps. That will be 200 steps per revolution. It has two motor windings (phase A and B) that must be controlled. The motor is rated at some maximum current per phase. That means, it will be the maximum current in each winding.
If we look at the data sheet for a specific motor we find:
Maximum current pr phase: 1.4 A
Resistance per phase: 4.2 Ohms
Inductance per phase: 15 mH
This is a double H-bridge that can be used with PWM to control the output current. It uses some NAND logic to make sure there will be no shoot-trough shortening the supply voltage by opening both high-side and low-side MOSFET’s at the same time.
I started out this design actually using an extra voltage source (battery) for driving the high side MOSFET’s. Then R24, R25 R26 and R27 had 9V extra voltage than the MOSFETS.
Sometimes you’ll need some given digital outputs for some given inputs in your project. At least I do. There are several ways to do this, but I will use the Karnaugh mapping method.
First let’s be familiar with some Boolean expression. If we have A and B as input of an AND gate, and the output will be C. Then the expression will be:
C = A·B
This is a simple pulse generator to use for testing purposes. It uses the LM324 operational amplifier, and the frequency can be controlled with a potentiometer. The LM324 chip is not that fast, so the frequency will be limited.
I used LTSpice for schematics and simulation:
This is an article on how to simulate 4028 in LTSpice. If you need a custom IC that you know how to simulate, This method might be of interest. The principle is to create a schematics with the same name as a symbol. These files must be located in the same folder.
