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Author Topic: Multiplexing 3 Stepper Motors  (Read 2317 times)

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Offline frank26080115Topic starter

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Multiplexing 3 Stepper Motors
« on: November 25, 2007, 06:33:55 PM »
Actually, I'd like to build a small 3D CNC milling machine, but I want to use as little number of pins as possible, so if I multiplex the common pin on all three motors, I can use 7 pins on my MCU instead of 12. Also I only need 7 MOSFETs to drive all the steppers.

But then, I can only use one motor at once and I lose a bit of accuracy.

Or should I use two serial to parallel 74HC595 latch shift registers? It'll be more of a pain in the ass but I'd maintain all control. I'd need 12 MOSFETs, but only 4 MCU pins.
« Last Edit: November 25, 2007, 06:37:30 PM by frank26080115 »

Offline jsmoker

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Re: Multiplexing 3 Stepper Motors
« Reply #1 on: November 26, 2007, 08:26:13 AM »
I may be totally wrong about this, but I thought 4 lead stepper wires don't have a common wire (since they're only bi-polar).  On a side inquiry, if it would work, why would it reduce accuracy?

Offline Admin

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Re: Multiplexing 3 Stepper Motors
« Reply #2 on: November 26, 2007, 09:03:32 AM »
How much current do you need?

Why not get stepper driver? Something like this would only need 2 pins/stepper:
http://www.sparkfun.com/commerce/product_info.php?products_id=8368

or (scroll halfway):
http://www.active-robots.com/products/motorcon/

Offline frank26080115Topic starter

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Re: Multiplexing 3 Stepper Motors
« Reply #3 on: November 27, 2007, 09:28:16 AM »
but i can use any half bridge IC... I have L298HNs I can use.

 


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