Motor/Stepper v2 & Switec X27.168 & Netduino?

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digital_archivist
 
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Motor/Stepper v2 & Switec X27.168 & Netduino?

Post by digital_archivist »

I understand that, due to its low current requirements, I can drive a Switec X27.168 stepper directly from an Arduino, Netduino, Raspberry Pi, etc. without a shield being required. (I've actually managed to do this with a Netduino Plus 2). But I like the idea of using I2C to control the Switec. Is there any reason (other than my own incompetence) why I wouldn't be able to make this combination (Netduino -> I2C -> Adafruit Motor/Stepper v2 -> Switec X27.168) work?

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adafruit_support_bill
 
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Re: Motor/Stepper v2 & Switec X27.168 & Netduino?

Post by adafruit_support_bill »

Do you have a link to a spec sheet for this motor?

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Re: Motor/Stepper v2 & Switec X27.168 & Netduino?

Post by digital_archivist »

You can download the X27 datasheet from here: http://jukenswisstech.com/index.php/documentation/.

You might also want to take a peek at Guy Carpenter's Gaugette info: http://guy.carpenter.id.au/gaugette/blog/page/2/.

Finally, I purchased the X27 I'm playing with (mounted on a handy breakout board) from: https://www.tindie.com/products/TheReng ... out-board/.

Thanks for taking a look at this!

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adafruit_support_bill
 
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Re: Motor/Stepper v2 & Switec X27.168 & Netduino?

Post by adafruit_support_bill »

The real technical specs are restricted. But from what I can gather it looks like a bipolar stepper designed for 5v and with very low current demands. You should be able to drive it from the motor shield without problems.

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Re: Motor/Stepper v2 & Switec X27.168 & Netduino?

Post by digital_archivist »

That's great! I'll pick one up and give it a try. Thanks again!

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colinives
 
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Re: Motor/Stepper v2 & Switec X27.168 & Netduino?

Post by colinives »

I know this is an old post but I'm interested in making a gauge for a very low power application where the gauge only updates position a few times a day and I want constant display - a LED would take power all the time, this won't. How do I deal with know where the gauge is - or when it has reached either end of its travel?

Thanks

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Franklin97355
 
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Re: Motor/Stepper v2 & Switec X27.168 & Netduino?

Post by Franklin97355 »

To know where the pointer is you would use an absolute position encoder and read it when you need to change positions. The end points would be determined by trial and error

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colinives
 
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Re: Motor/Stepper v2 & Switec X27.168 & Netduino?

Post by colinives »

Thanks ... I was thinking more of knowing when you have wound it back - is there a built in limit switch in the motor so, say, you click back 600 steps and know that it's definitely back at the start.

Also, is my idea to use this as a permanent visible gauge - even when the product is in standby - viable? The gauge (monitoring a slow moving liquid level change) will be updated about six times a day for two days ... Gradually changing from 'empty' to 'full' over that time. In this case I'll be delivering 600 pulses (at relatively slow speed) with only a needle to move over two days but is there a way of 'guesstimating' how many mAh I'll be using per full sweep and back again?

Thanks

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adafruit_support_bill
 
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Re: Motor/Stepper v2 & Switec X27.168 & Netduino?

Post by adafruit_support_bill »

There is no built-in limit switch for the ones we have in the store: https://www.adafruit.com/product/2424 And I haven't seen any in the spec sheets I have seen for others.

Car companies would spec them with limit switches if they were needed. I'm assuming that the standard technique is to just run it back against the hard-stop to find the 'home' reference. Unlike a brushed DC motor, it doesn't hurt a stepper electrically to stall. And since these things don't have much torque in the first place, it can't really do any mechanical damage.

These should hold position un-powered if not disturbed.

I haven't run any tests on these yet, but the phase resistance is listed as 260 ohms. At 5v, that would be about 2mA/phase.

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colinives
 
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Re: Motor/Stepper v2 & Switec X27.168 & Netduino?

Post by colinives »

Ok, Thanks.

So i'm still struggling to know how to 'zero' them to a reference point - you can then clearly do counted steps to get to the desired position without feedback but how can the code be sure the start point is correct every time it runs as you need in a gauge ('0' position) :-/ If these have a limited 'swing' what happens when you reach each end and continue sending steps. Sorry if I'm being a bit stupid over this but sending too many pulses will result in increased power consumption as the motor stalls at the end points :-/

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adafruit_support_bill
 
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Re: Motor/Stepper v2 & Switec X27.168 & Netduino?

Post by adafruit_support_bill »

If these have a limited 'swing' what happens when you reach each end and continue sending steps.
Not much. They don't have enough torque to damage anything.
sending too many pulses will result in increased power consumption as the motor stalls at the end points
It may run longer than absolutely necessary, but stepper motor current does not increase with load or when stalling.

For an example, see this library. The "zero()" function just steps CCW for the max number of steps.
https://github.com/clearwater/SwitecX25

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colinives
 
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Re: Motor/Stepper v2 & Switec X27.168 & Netduino?

Post by colinives »

Ah, ok - now I understand :-) thank you.

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fixxit
 
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Re: Motor/Stepper v2 & Switec X27.168 & Netduino?

Post by fixxit »

Current per phase is not correct.
Ohms Law: I=E/R
5volts / 260 ohms = 0.0192 Amps or 19.2 milliamps per phase.
Still within what most microprocessors can supply.

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colinives
 
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Re: Motor/Stepper v2 & Switec X27.168 & Netduino?

Post by colinives »

That's great - thanks everyone!

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