Stepper Motor Driver Differences

What's the difference between the stepper driver for Reprap and Sparkfun's EasyDriver? Is it just the way the wires connect to the board, or is there something more?

sparkfun easydriver only does 750mA which may or may not be enough. It uses the allegro A3967, whereas the reprap drivers use the allegro A3949. I have ordered the A4983 carrier boards from pololu for my reprap, as the A4983 is far superior to the others on a number of fronts.

Thanks.

Triffid_Hunter Wrote:
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> sparkfun easydriver only does 750mA which may or
> may not be enough. It uses the allegro A3967,
> whereas the reprap drivers use the allegro A3949.
> I have ordered the A4983 carrier boards from
> pololu for my reprap, as the A4983 is far superior
> to the others on a number of fronts.

forgive me for asking from what i have read that is a far better chip are there any diagrams on how to make a board for it, or could a person just replace the one on the spark fun one with that one.?

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[mike-mack.blogspot.com]

pololu provide A4983 on a board. note that you'll have to add a heatsink if you want more than half an amp out of it

how much coding difference is there to use one of those stepper motor driver has well, or is it pretty much the same.?

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[mike-mack.blogspot.com]

it's the same, just need to change steps per rev to take the microstepping into account if you use it. all the various stepper drivers accept step/dir signals.

the opto endstop connectors are just pass-through, nothing to do with driving the steppers at all

The A4983 datasheet has a sample board layout ... oversized, so you'd have to shrink it and mess with the colors to get black/white before printing it as a board, but it's certainly a place to start.

The pololu board is advertised some places as a "breakout board" ... and that's pretty much what it is; it houses the chip and minimal necessary support components and otherwise just provides a .1 inch pad spacing for the chip signals. It's probably not much, if any different than the suggested board on the datasheet.

-- TWZ

Triffid Hunter:

You mentioned putting a heatsink on the Pololu board on my "drive by" thread as well. Since you have experience with this board, how do you mount a heatsink on it? According to the chip datasheet there is a thermal/groundplane on the bottom, and they recommend holes underneath the chip to vent it.

Generally I would expect putting a heatsink on top, over the plastic case to be only minimally useful, but perhaps with the small size it will help enough to make a difference ... you tell me. Otherwise does the Pololu have the bottom drilled beneath the chip with a large enough hole to bond some kind or radiator to it?

Thanks yet again!

-- TWZ

Edited 1 time(s). Last edit at 01/19/2010 09:29PM by ColonelZen.

i was wondering about that too. thanks for asking

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[mike-mack.blogspot.com]

yeah I'm just slapping it on the top. works well enough that a 40x12mm heatsink (1/3 of a pentium 133 cooler) triples the current I can put through it from 0.5A to 1.5A.

the heatsink gets burning hot when running near maximum current, which tells me 2 things: the chip is effectively transferring heat from its top surface, and the heatsink could be larger.

I've considered drilling out the bottom of the board and adding a copper slug or something, but I'm really not sure that the hassle is worth the gains.

I've also considered soldering a bunch of thin copper wire hairs to the bottom where the thermal vias come through. Pololu did add them, but there's just not enough board space for effective cooling.

Hello everyone,
I am in the process of completing my stepper v2.3 driver boards, and came across the recent posts for pololu electronics.
I have a few questions related to the pololu product offering:
1. Will the pololu stepper-boards inter-operate with the Sanguino Gen3 board?
2. Is it correct to say that the extruder board is also completely replaced with one of these boards? I have had issues with sourcing all relevant components for the extruder, especially the dmos full-bridge motor driver and mosfets. The pololu offering seems like a reasonable alternative (provided they ship to South Africa )
3. The ideal configuration would be that I can use existing sanguino motherboard h/w and s/w and connect pololu boards w/ modified headers. Is this a reasonable expectation, or fantasy?

Thankyou, in advance.
Marius Botha
Pretoria, South Africa
[mariushermanbotha.wordpress.com]

1. Yes but you need cooling.
2. No you still need a MOSFET to switch the heater and a resistor and cap for the thermistor input.
3. That is what Adrian has done here: [blog.reprap.org]

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[www.hydraraptor.blogspot.com]

the extruder board is an atmega168 + stepper controller + high current mosfet + rs485 transciever, with a few gadgets hung from spare pins on the '168

I'm planning to plug my extruder directly into my main board, my '168-based arduino has enough I/O to drive the whole reprap. I even have a spare pin for something, currently I have a second mosfet hooked up. I used the IRL3803 which can handle 7A with no heatsink, so 2A should barely warm it up

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Wooden Mendel
Teacup Firmware

I'm very new to all of this without much previous experience in electronics, stepper motors, etc.

I've been waiting for Makerbot to get electronics back in stock but came across the EasyDriver.

EasyDriver

Has anyone used or planning on using EasyDriver? With my limited knowledge I don't want to stray too far away from the path.

sasharp65 Wrote:
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> I'm very new to all of this without much previous
> experience in electronics, stepper motors, etc.
>
> I've been waiting for Makerbot to get electronics
> back in stock but came across the EasyDriver.
>
> EasyDriver
>
> Has anyone used or planning on using EasyDriver?
> With my limited knowledge I don't want to stray
> too far away from the path.

i am going to use teh pololu one here is a link, it has allot of good things going for it.

A3983
[www.pololu.com]

i think there are a few people here using it. and it is not too pricey too

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[mike-mack.blogspot.com]

Thanks!

Maybe when I'm to the point of actually building my Mendel, someone will have created a tutorial on how to use them for the Mendel? The are a lot cheaper then MakerBots price of $35 a piece.

I guess I could always buy them and learn to play with them before that time.

Next issue - what to do about the printed parts. I need to come up with an inexpensive solution until I can print out my own.

[objects.reprap.org]

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[www.hydraraptor.blogspot.com]