Basic stepper motor question

[GSR]

Dear all,

I need to build a stepper motor control using MC3479 stepper motor driver. However, I don't know much about stepper motor and the stepper motor driver. I am not sure whether MC3479 is a standard stepper motor driver, but I hope my question are simple for everyone.

• If I tell the stepper motor to position A, do I need to keep the current even to keep the motor at that position? Or it will lock in that position? <===== the smiling face that I like the most
• If the load is too heavy and the motor cannot reach position A with one clk pulse to the stepper motor driver, what will happen?
• If I want to ask the motor to stay in a position, should I send a logic 0 to clk pulse?

[EricLarsen]

I'm not really familiar with the MC3479. It looks like it might be a fairly standard stepper driver, and most of them work about the same way.

To answer your questions generally, steppers are fairly simple motors and are easy to control. That's why they are so popular.

To keep a motor in a constant position, you 'may' have to keep the current on. It depends on the configuration of the load. A stepper motor will generate no torque without current. But if your load is self locking, such as a horizontal motion or a vertical motion with a high pitch drive screw, it may stay in position. Another option is to use a relay brake that engages when the current is shut off.

If your load is too heavy, the motor will stall. A stall in a stepper motor is usually easy to detect just by the sound it makes. Most stepper motor drivers have a stall detect feature, where an encoder is attached to the load and if the encoder doesn't keep up with commanded position, the controller will detect an error. If your load is too heavy, there really isn't much you can do to correct it other than get a bigger motor. Slowing the velocity and acceleration can help some, as can changing gear ratios, but that doesn't always work.

Does your application require you to start with an MC3479? There are many manufactures of stepper motor controllers that would save you a lot of time instead of building your own.

[GSR]

I'm not really familiar with the MC3479. It looks like it might be a fairly standard stepper driver, and most of them work about the same way.

To answer your questions generally, steppers are fairly simple motors and are easy to control. That's why they are so popular.

To keep a motor in a constant position, you 'may' have to keep the current on. It depends on the configuration of the load. A stepper motor will generate no torque without current. But if your load is self locking, such as a horizontal motion or a vertical motion with a high pitch drive screw, it may stay in position. Another option is to use a relay brake that engages when the current is shut off.

If your load is too heavy, the motor will stall. A stall in a stepper motor is usually easy to detect just by the sound it makes. Most stepper motor drivers have a stall detect feature, where an encoder is attached to the load and if the encoder doesn't keep up with commanded position, the controller will detect an error. If your load is too heavy, there really isn't much you can do to correct it other than get a bigger motor. Slowing the velocity and acceleration can help some, as can changing gear ratios, but that doesn't always work.

Does your application require you to start with an MC3479? There are many manufactures of stepper motor controllers that would save you a lot of time instead of building your own.

Thanks for your reply

Yes! I have to use MC3479.

Now I can control it, but I still need to figure out how to control it at varying speed