Testing Stepper Motors/Drivers

[joegibParticipant @joegib]

Hi Gents,

I’m preparing to build the standalone control device designed by ‘Kwackers’ (Steve Ward) to drive a dividing head or rotary table via a driver and stepper motor. This could be described as a poor man’s DivisionMaster though it appears very capable and is now pretty mature. The project (including links to the circuit, PCB layout, manual etc), is discussed on the CNC Zone here:

http://www.cnczone.com/forums/open_source_controller_boards/47007-rotary_table_indexer.html

I’ve acquired a suitable stepper motor off Ebay and this was apparently salvaged from a Sato R400 label rewinder. Interestingly, the seller (nice gent) included what seems to be the related driver daughterboard plus all the off-board wiring and switches that go with it. I’ve tested the stepper motor (Nanotech-Munich) using a primitive driver I have and this runs very sweetly. I’ve also done a crude test of the Sato driver-motor combination — powering it locks the stepper rock solid (which is encouraging). The only data interface to the driver board is a 2-wire flylead terminated by what appears to be a metal-encased 5-pin DIN socket. Presumably, the two connected wires are DIR and STEP. I suppose I could get a break-out-board for the PC printer port (and suitable software) but I’m reluctant to invest money only to find out that the driver is duff or a special that can only be driven by the parent board.

I therefore need to find some way to feed suitable signals to the data interface. As I understand it, the STEP signal is simply a stream of square-waves at TTL levels fed to the driver main IC which amplifies these signals to (motor) power levels and feeds them in a sequence to the stepper so as to produce rotary motion.

I have an old Labgear audio signal generator that can output sqare waves at TTL levels so I was wondering whether a signal fed from this could be used for the purpose. Is this feasible please? If so, at what conservative frequency should I run the generator to produce rotary motion? And what should I do (if anthing) about the DIR (direction) signal?

Thanks

Joe

PS — I appreciate that the above may be utterly wrong-headed but I had to ask!

Edited By joegib on 14/10/2010 16:46:12

[joegibParticipant @joegib]

[john swift 1Participant @johnswift1]

Hi Joe ,

 

If your signal generator has TTL level output from 5 Hz to 500 Hz

I see no reason why you can’t use it to  test your stepper driver 

 

as plan B you could build a simple oscillator with a NE555 ic or TTL /CMOS schmitt  buffer ic

 

If you need more info , I’ll post a few circuits

 

           John

 

 

 

[Gone AwayParticipant @goneaway]

If all you want to do is test the interface, you should be able to simply strap the DIR input to either 5V (perhaps through a pull-up resistor) or ground and then manually tap a 5V wire to the STEP input and see if it steps (again you should probably use a pull-up rather than the raw 5V).

 

Flipping the DIR level should reverse the direction of course.

[joegibParticipant @joegib]

Thanks John and Sid.

 

After heaving the signal generator out of the attic I realised my instinct was right — I had been wrong-headed! While quite good of its type, it is, of course, an analogue AC signal generator whereas what I’d need, I believe, is a DC pulse generator.

 

Initially, I’ll give Sid’s simple technique a go to see whether I can get some life out of the driver/motor. But I’ll also have a go at making a simple generator if it’s something I can quickly put together on a breadboard. So, John, if you’ve got a simple circuit to hand, I’d appreciate a copy please (I’ve got loads of 555s).

 

Thanks again

 

Joe

[Billy MillsParticipant @billymills]

Joe

You probably can use your audio oscillator, you just need a simple interface. Any small npn transistor emitter to ground. Audio osc to base, collector to STEP input – might need a pull up – say 1K ohm from STEP to +5V. Set the oscillator for 100Hz, 1V or so output. It probably has a source impedance that will limit the base current to a safe value. If you are worried then stick a 1Kohm in series with the base.  The pulse shape will probably be quite quick enough for a stepper driver without squaring up. 

Regards,

Alan.

[john swift 1Participant @johnswift1]

Hi Joe ,

 

any of the circuits should work

 

if you don’t have any inverters in your spares box any not gate gate

can be used  7400 4011 0r 4093 etc

   John

[joegibParticipant @joegib]

Thanks again gents. I’ll give these techniques a go over the weekend.

 

Joe

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