alternatives to MC3479 stepper driver IC

[kinetic (Steve)]

Hi,

I'm currently working on adding the stepper-focus option to my existing
Bartels Stepper drive system.

Before buying an MC3479 IC, are there any alternatives that are similar?
I may as well try and use something in my junk pile rather than buy
this IC if I'can avoid it.

I have several TA7774P ICs from old 5 1/4" floppy drives that seem to
be a similar driver IC almost pin for pin......but only almost.

They seem to drive a bipolar Stepper 12v 500ma so I thought maybe I
would try one.

Would anyone be able to take a quick look at the TA7774P datasheet and
tell me yes or no if I could do a swap for the MC3479?
http://www.marktechopto.com/pdfs/tos..._datasheet.pdf

Mel's add on circuit:
http://www.bbastrodesigns.com/Steppe...l#_Toc90090796

I don't mean a straight plug in swap, I realise some pins are in different
positions on the 16P DIL package.

I also posted this into the Scope Drive Forum.

thanks in advance,

Steve B

[hikerbob (Bob)]

Steve I'm playing with the EasyDriver v3 from Sparkfun at the moment. http://www.sparkfun.com/commerce/pro...oducts_id=8368

Features:

• A3967 driver configured for 8-microstep mode
• Compatible with 4, 6, and 8 wire stepper motors
• Adjustable current control from 150mA/phase to 750mA/phase
• Power supply range from 7V to 30V. The higher the voltage, the higher the torque.

As is it seems to work really well and there is some discussion on mistreating it at http://forum.sparkfun.com/viewtopic.php?t=17169

I've posted a piece on driving it with an Arduino at http://forum.sparkfun.com/viewtopic.php?t=17243 with some test code I used (the Arduino does not naturally give variable frequency output but by using timer interrupts it can be done).

I've been working tonight at lifting the mode pins from the PCB to allow control over the stepper mode so that I can use the various modes. I've run out of pins on the Arduino so I may end up using either 1/8th step or full step for slewing and ignore the rest.

I've had two different orders from Sparkfun and so far the service has been excellent. I use a number of bit's from them in my dew heater controller.

I need to play some more with the supply voltage and current limiting features of the EasyDriver to see what works well.

Bob

[kinetic (Steve)]

Thanks Bob, sorry I forgot to say thanks when I first read your
post.
I did get the 7774P to work but your suggestion looks like a
better breakout unit for experimenting, for sure.
The link I found for the Sparkfun unit had more features
in the breakout so you could select the step modes as well.
http://www.sparkfun.com/commerce/pro...oducts_id=9402

I'll get one of those, thanks mate.

Steve

[hikerbob (Bob)]

Steve I'd not realised that version was out yet. I was told that it was coming in a discussion on the Sparkfun forum but did not realise that it was so close. The enable/sleep modes look like they could be useful. I'm hoping that I can put the Alt axis motor to sleep when I'm not using it to conserve power.

I'll have to get a couple and have a play with them.

Bob

[mswhin63 (Malcolm)]

Hi All, I understand that 1/8 microstepping is good for focuser but wondering whether 1/8 microstepper will be good for DOB mount stepping?

[kinetic (Steve)]

Originally Posted by mswhin63

Hi All, I understand that 1/8 microstepping is good for focuser but wondering whether 1/8 microstepper will be good for DOB mount stepping?

Malcolm,

far better to microstep down to an even finer level.
A Bartel stepper drive can allow microsteps of 20 per step
and even 40 ( I think).
This is very smooth when refined and working sweetly.

1/8 steps per step may show as coarse steps at the eyepiece
and be unworkable with the reduction ratios needed for
tracking. I may be wrong though on that point.

Steve

[mswhin63 (Malcolm)]

On my technical understanding you are right, I just needed a practical view point as I have worked only with high speed applications for stepper control in the past.

Especially in zenith observing when the alt hardly moves the need for extremely fine control is important.

[kinetic (Steve)]

Originally Posted by mswhin63

Especially in zenith observing when the alt hardly moves the need for extremely fine control is important.

Malcolm,

I think, for that very reason, Dobs are fitted to an EQ or Poncet platform
to minimise that when users want to get serious about imaging.

Steve

[alistairsam]

Originally Posted by hikerbob

Steve I'm playing with the EasyDriver v3 from Sparkfun at the moment. http://www.sparkfun.com/commerce/pro...oducts_id=8368

Features:

• A3967 driver configured for 8-microstep mode

I've been working tonight at lifting the mode pins from the PCB to allow control over the stepper mode so that I can use the various modes.
Bob

Originally Posted by kinetic

Hi,

I'm currently working on adding the stepper-focus option to my existing
Bartels Stepper drive system.

Before buying an MC3479 IC, are there any alternatives that are similar?
I may as well try and use something in my junk pile rather than buy
this IC if I'can avoid it.

Steve B

Hi Bob, Steve,

were you able to use the A3967 or other alternatives with the bartels system? if so could you please post some info on how you did this with respect to the bartels system,
I'm trying to use the A4983 stepper driver from Allegro with the Bartels system and could do with some leads. Bojan mentioned there was a yahoo groups site that expained this, but have'nt been able to find it as yet.

Note on the A4983, you might want to give this a look as its an improved version of the A3967 and supports 1/16th microstepping and is very smooth. available in aus.
http://www.robotgear.com.au/Product.aspx/Details/409

i've used it very successfully with a picaxe mcu to drive a stepper.
http://www.youtube.com/watch?v=oO68oe5R-Ws

[kinetic (Steve)]

Alistair,
I ended up using the MC3479 in the end.
I made up a dedicated PCB with opto isolated control.
Added it to the Bartels system, enabled it in config.dat.
Works a treat with a small stepper on the focuser:
http://www.iceinspace.com.au/forum/s...ad.php?t=51301

Steve

[bojan]

Alistair,
At the bottom of the Bartel's page there is a link to this yahoo group..
http://tech.groups.yahoo.com/group/scope-drive/
You have to join first.. and you will find everyone there, including Mel himself :-)

[Ritchie-l (Ritchie)]

A4983 stepper controller.
they are in stock in Clayton if anyone is interested in them.
details are http://www.joreigtechnologies.com.au...egula4983.html

or email sales@joreigtechnologies.com.au