Dediated stepper drivers vs ULN2803

[fuper]

Hey guys -

Had a question. I've been looking at driving stepper motors, just experimenting with an Arduino.

I have a bunch of ULN2803 and I know i can use those to drive a stepper, requiring 4 IO pins. This seems straight forward enough if my stepper current requirements are met.

Now what are the advantages of dedicated stepper drivers like the A3967 or seemingly more common, the l297+L298 combo which costs almost $15 US bucks for both?

I know they include chopper circuit support which as I understand is to limit current? Is this provided so they support a wide range of steppers?

Confused.

Shane

 

[shortbus=]

Not knowing what you are using the steppers for make answering harder. A dedicated driver is ALWAYS going to make a stepper motor easier to use.

A uC is going to need other high amperage devices to actually drive the motor. Plus the code that can need troubleshooting to get correct. And if you want to vary the speed it gets even harder. In the end a uC is going to cost as much or more than a dedicated driver.

The L297/L298 limits both the current and speed that you can drive the motor at. IIRR around 140RPM is the limit on the L297/L298.

If making a CNC and using a uC for the driver then you get in to the problem of interfacing to your CAM program. That is not a problem with a dedicated driver. In the end it's all up to you how you do it, but my vote would be for a dedicated driver.

 

[SABorn]

The important fact here is what sort of stepper motor you have, as a unipole stepper can be driven with 4 x N channel transistors of mosfets, but a biploar stepper will require a H-bridge driver, which a dedicated driver is.

Pete.

 

[3v0]

Take a look at this page. It may be what you are looking for.

 

[fuper]

Good link! Haven't finished reading it through about to run to the gym.

I realize my question was pretty open. Yes the problem domain was in theory a CNC machine but I really just want to learn rather than expect to build one.

If I went unipolar, couldn't I use something like a 74HC595 to a ULN2803 and drive the motors however fast I want?

I will have to read up more on controlling current on motors. I built a robot using battery operated screwdrivers that I cut in half [works really well that] and never really bothered with the current.

Thanks guys!