pololu stepper driver is dead - do I need to pullup ENABLE?

Hello All

After days of designing and implementing my pololu stepper driver board, nothing is happening.

I have power but nudging the axis does nothing.

Question - do I need to pull the ENABLE pin high in the same way the G3 stepper drivers do?

I am running off a G3 makerbot motherboard. The cable is fine and using a G3 stepper driver all is well...

any advice would be appreciated.

Scratch that - it seems ENABLE must be low to enable the board so that is not my problem

Damn - I am at a loss now.

MS1 is pulled low
RST and SLP are pulled high
the board has power
there is continuity from the IDC to the various pins of the breakout board
motor driver pins have continuity to the motor mount (4 pin terminal)
Motor LEDs light up when I rotate the motor by hand.

God - I hope I have not fried my pololu ...

Edited 1 time(s). Last edit at 12/04/2010 04:16PM by AgeingHippy.

With enable low, reset and sleep high it should energise the motor, assuming the pot is not set at 0 current.

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[www.hydraraptor.blogspot.com]

Now that's most bizarre....

Last night no matter what I did, the chip seemed dead. All my testing and continuity checks showed 5 and 12v where it was supposed to be. Continuity where there should be and no shorts I could find.

This morning I thought I would try testing half and micro steps. Plugged everything in and powered on. Lo and Behold - the motor terminals were energised (I added LEDs) All still on full step mode. Attached a motor (switching off the power first of course) and tested. all good. ><

Weird Cannot see why it should be working now and not last night.

Anyway - all seems fine at the moment and micro-stepping seems to work.

I am pleased I included the 'unnecessary' LEDs to indicate power to the board and energising of the coils.

AgeingHippy Wrote:
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> I am pleased I included the 'unnecessary' LEDs to
> indicate power to the board and energising of the
> coils.

HI, great you fixed your problem.
Just one question, where did you add th LEDs to the board as it would be good to have some type of inducator if they are working.

Thanks
Auzze

Hi Auzze

Sorry about the delay in responding.

Here is a rough schematic of how I have attached the LEDs.



These will indicate whether your motor coils are being energised in much the same way as the G3 stepper drivers are see Schematic.

You may wish to reverse the direction of the bottom 2 LED's in my schematic... not sure exactly which orientation they should be in for sequential stepping... but they will indicate none-the-less.

Cheers

Edited 1 time(s). Last edit at 12/07/2010 08:23AM by AgeingHippy.

Does this LED setup work for micro stepping? I assumed the LEDs would be driven off the STEP/DIR inputs to the driver.

jv4779 Wrote:
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> Does this LED setup work for micro stepping?

It should, but I think it may look a little strange unless the motor is connected as well, or at least a dummy load so the current controller kicks in.

If the driver did voltage control, it would work fine with no load, however the microstep driver in the A4983 provides various values to the current controller subsystem, which works great for motors but not very well at all if the load won't take much current at the supply voltage.

With a suitable load connected however, you should see the leds brightening and dimming in response to step pulses.

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Wooden Mendel
Teacup Firmware

It seems to work for micro-stepping. Not sure how much you want to get from it but there is some flickering to indicate something is happening.

I don't really understand it, but there are some instances where both LEDs in a set are lit!!?? I don't know how that can be since an LED should only light if the voltage accross it is in the correct direction, but there you go. Maybe the voltage is osscilating across it fast enought that they both look lit at the same time?

Yes when microstepping in fast decay mode the LEDs are flashing so fast that your eye / brain perceives them to be on at the same time and the same without microstepping at high step rates. Once something is flashing above about 60Hz it looks solid.

It is much more useful to have the LEDs on the stepper outputs than it is on the step and dir signals.

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[www.hydraraptor.blogspot.com]

if you want to "see" things that are flickering, wiggle your eyes quickly while watching it- if you get a trail of spots, it's flashing. if you get a solid trail, it's either on, or flashing extremely fast. You can also look at it through a fan, which should cause the apparent brightness to wax and wane at the beat frequency of the fan blades and the led frequency

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Wooden Mendel
Teacup Firmware