dividing control of stepper motors

Archiver

Hello,

I'd like to control four small stepper motors with a stamp using the
inexpensive ULN2003 transistor array that is shown in StampWorks experiment #
26, but I don't want to use all 16 pins for control (four pins per motor).

The motors don't need to be run at the same time, so I was thinking, since
unipolar steppers have four coils with one common line, that I could hook up
the four motors' coils together, but choose which motor to run by only enabling
the common line of the motor that needs to be controlled.

Again, i'm running out of pins fast, so the least number of pins to choose
which of the four motors to use would be two pins in different combinations (0
to 3). I guess I would need some sort of quad logic chip that takes two inputs
and has four separate output pins? I'm not sure. Then i'm also not sure what
device to put at the end those outputs to connect and disconnect the common
wire from each stepper, perhaps a simple relay for each motor or another
transistor array?

If anyone has experience with this and doesn't mind sharing their solution I'd
appreciate it.

Thanks,
Stewart






--
Stewart Mayer, stew@k... on 01/07/2002

Archiver

At 12:29 PM 1/7/02 -0600, you wrote:
> I guess I would need some sort of quad logic chip that takes two inputs
>and has four separate output pins?

Take a look at the EDE1200 (five or six wire motors) or the EDE1204 (four
wire motors). It does just what you describe. www.elabinc.com in the
'EDExx IC Family' section of the website.

>Then i'm also not sure what
>device to put at the end those outputs to connect and disconnect the common
>wire from each stepper, perhaps a simple relay for each motor or another
>transistor array?

Hookup schematics are in the EDE1200 & EDE1204 datasheets. PDF datasheets
are downloadable at the above address, or e-mail me off-list with your
mailing address for a CD-ROM of our Stamp related IC's.


Todd Peterson
E-Lab Digital Engineering, Inc.

(816) 257-9954 FAX: (816) 257-9945
www.elabinc.com

Archiver

You could use a couple of 75HC595s to create 16 outputs from just three Stamp
pins and go from there. The 75HC595 is also covered in StampWorks.

-- Jon Williams
-- Parallax


In a message dated 1/7/02 12:28:58 PM Central Standard Time,
stewlist@k... writes:


> Hello,
>
> I'd like to control four small stepper motors with a stamp using the
> inexpensive ULN2003 transistor array that is shown in StampWorks experiment
> #
> 26, but I don't want to use all 16 pins for control (four pins per motor).
>
> The motors don't need to be run at the same time, so I was thinking, since
> unipolar steppers have four coils with one common line, that I could hook
> up
> the four motors' coils together, but choose which motor to run by only
> enabling
> the common line of the motor that needs to be controlled.
>
> Again, i'm running out of pins fast, so the least number of pins to choose
> which of the four motors to use would be two pins in different combinations
> (0
> to 3). I guess I would need some sort of quad logic chip that takes two
> inputs
> and has four separate output pins? I'm not sure. Then i'm also not sure
> what
> device to put at the end those outputs to connect and disconnect the common
> wire from each stepper, perhaps a simple relay for each motor or another
> transistor array?
>
> If anyone has experience with this and doesn't mind sharing their solution
> I'd
>




[noparse][[/noparse]Non-text portions of this message have been removed]

Archiver

I looked at the stampworks experiment and that is an excellent suggestion. I
also looked at the elabinc.com chips, but they would require more pins,
especially for four than I can part with.

Thanks for the help!

Stewart



On Mon, 7 Jan 2002 19:19:24 EST, jonwms@a... wrote:
>You could use a couple of 75HC595s to create 16 outputs from just three Stamp
>pins and go from there. The 75HC595 is also covered in StampWorks.
>
>-- Jon Williams
>-- Parallax
>
>
>In a message dated 1/7/02 12:28:58 PM Central Standard Time,
>stewlist@k... writes:
>
>
>>Hello,
>>
>>I'd like to control four small stepper motors with a stamp using the
>>inexpensive ULN2003 transistor array that is shown in StampWorks experiment
>>#
>>26, but I don't want to use all 16 pins for control (four pins per motor).
>>
>>The motors don't need to be run at the same time, so I was thinking, since
>>unipolar steppers have four coils with one common line, that I could hook
>>up
>>the four motors' coils together, but choose which motor to run by only
>>enabling
>>the common line of the motor that needs to be controlled.
>>
>>Again, i'm running out of pins fast, so the least number of pins to choose
>>which of the four motors to use would be two pins in different combinations
>>(0
>>to 3). I guess I would need some sort of quad logic chip that takes two
>>inputs
>>and has four separate output pins? I'm not sure. Then i'm also not sure
>>what
>>device to put at the end those outputs to connect and disconnect the common
>>wire from each stepper, perhaps a simple relay for each motor or another
>>transistor array?
>>
>>If anyone has experience with this and doesn't mind sharing their solution
>>I'd
>>
>
>
>
>
>[noparse][[/noparse]Non-text portions of this message have been removed]
>
>
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--
Stewart Mayer, stewlist@k... on 01/08/2002