Stepper Controller IC Options

I've been wanting to design a stepper controller with microstepping, but stepper drivers seem to be difficult to obtain. Here are some options I've been looking at. Does anyone have any suggestions of other drivers?


Makerbot/Gen3 uses the Allegro A3982 which is available from electronics suppliers (mouser/digikey/etc), but it only supports full and half stepping.

The Allegro A4983 (that pololu uses) supports full/half/quarter/eighth/sixteenth stepping, but is near impossible to find (as are any other A498X chips). The only place that had it listed as even going to be in stock was Newark with 100+ days lead time. I could buy the board from Pololu for $12 but I would prefer to design my own.

I would prefer to use a surface mount chip, as I find them easier to design for and solder. Not to mention it looks really nice

[www.allegromicro.com] Has quite a few driver chips, I assume 2A is the minimum that you would want for NEMA17, but what about a NEMA23? Price and availability are a factor as well, I would like to stay under $7USD/chip, preferably $5 or less. Does anyone have any suggestions?

Edited 1 time(s). Last edit at 04/19/2010 03:59PM by jeffpark_.

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[www.binaryconstruct.com]

There is an open source discreet design that is part of the EMC2 project. Look-up LinuxCNC forum archives using your favorite search tool

Also note: there is a dedicated sub forum for stepper related issues, where I asked this very question a few months ago.

-julie

Digikey is showing that they will have stock on 4/22 and their price is $4.97/ea.

Buzz

buzzard192 Wrote:
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> Digikey is showing that they will have stock on
> 4/22 and their price is $4.97/ea.
>
> Buzz

That is good news! Thank you both for the info.

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[www.binaryconstruct.com]

I recently purchased 20 H-bridges from here:

http://cgi.ebay.nl/TLE5206-2GP-H-BRIDGE-5A-DC-MOTOR-PDSO-20-QTY-2_W0QQitemZ170433281344QQcmdZViewItemQQptZLH_DefaultDomain_212?hash=item27ae9d7d40#ht_1118wt_810

The idea was to not implement microstepping but go way further (nanostepping?) using PWM on one half of each bridge.

I haven't done any experiments with them yet so I cannot tell you much more than that ;-)

Reinout,
Stepper motors are not designed even for micro-stepping. When the A4983s do 1/16th steps, it is a given that the stage movement per 1/16th step will be bigger for some micro steps and smaller for others. The cumulative error could make you as much as one full micro-step off in the middle of the range. It does not effect whole steps however, so 16 micro-steps will always equal one normal step, just shorter in some spots and longer in others to balance out each full step.

If you really want to get very small stage movement repeatably and accurately, you either need to use gears to step down the movement from the stepper, or throw away the stepper altogether and us DC brushed motors with gear boxes and optical encoders. If properly done, this is much more accurate. But this is also far more complicated.

Mike

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Mike,
the motivation to do 'nano stepping' is to make the motors run smoothly when they are stepping very slowly, so my PlyRap stops shaking itself loose.

My intent is to have the G-code interpreter drive the machine at a granularity of either half or whole steps as the DDA does now, but that my new DDA will smoothen the transitions between these steps.
I envision that such a scheme will make my printer a lot less noisy while it does not require positional repeatability at the 'nano step' level.

Thanks!

Reinout

... or use the right steppers - i have some 3-phase-steppers from Berger-Lahr with appropriate controllers which are specified with 200/400/500/1000 steps per turn in normal mode and 2000/4000/5000/10000 with microstepping.

The possible systematic aberration is specified wit +/- 6 arcmin or +/- 0.1 degree with a maximum step-resolution of 0.036 degrees with 10000-spt-microstepping.

The aberration error is a factor if you have changing loads, so if you drive with a constant load or a gearbox you can reduce this dramatically ...

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Viktor
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Reinout,

In that case, the nano stepping makes perfect sense. Making multiple PWM channels to control 2 or 3 axes at once is a bit of work. You may find it easier to use a prebuilt micro stepper.

I think you will find little improvement over the 1/16th microstepping of the A4983, but if you want to go further, here is an App Note on PIC microstepping that discusses exactly what you are talking about.


Stepper Board is another predesigned micro stepping controller that advertises smooth motion.

4A Micro Stepper does not mention microsteps per step, but claims up to 5000 steps per revolution.


Here is another App Note on a current sensor PWM controller for smoother operation.

Hope this helps.

Mike

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... here is a datasheet of a 1/256-microstepping driver, which can turn a standard 1.8°/200steps-stepper until 51200 steps per turn.

I tested it with a Nema34-2Nm-Motor @3Amps and it's really soft and accurate driving, but with max. 10kHz you can use it in real life only until 1/32 microstepping (6400 steps per turn) ... with higher microstepping the moving speed isn't fast enough for milling or fabbing (but it's something more accurate then either ).

The Berger-Lahr-steppers with microstepping in 10000steps-mode can be driven until 200kHz, but i have the same speed as 'only' in 1000steps-mode with 20kHz ... at higher clock-speeds the motor stalls ...

Edited 1 time(s). Last edit at 04/22/2010 03:26AM by VDX.

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Mike, Viktor,

thanks a lot for those great links :-)

I'll delve into them over the weekend,

R
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Edited 1 time(s). Last edit at 04/22/2010 04:56PM by Reinout Heeck.

The IM384 has truly fantastic specs, and easy connection to the motor with screw terminals. But online prices seem to be high. $310 down to $30 used on eBay.

Mike

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Team Open Air
Blog Team Open Air
rocket scientists think LIGHTYEARS outside the box!

... i've got my three IM483 together with some mechanical parts for something below 100 Euros from a german CNC-fellow what was a fair trade ... but actually we have running an exchange-group where we swap spare parts among a small (closed) community.

So i received the Berger-Lahr-steppers/controllers, the lasers, filters and some other usefull stuff too without any payment - in exchange of some specific help/development and parts i found in my basement ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

A selection of the Allegro micro parts

there are L6208's and L6228's

If you hunt around they can be had for cheap, but on the big players they can be quite pricey.