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Author Topic: Powering down error
cazkade
Newbie
Posts: 2
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Post Powering down error
on: October 4, 2019, 12:09
Quote

Hello and thank you for creating this awesome machine. I have just built my own polargraph using this tutorial online: https://www.youtube.com/watch?v=T0jwdrgVBBc&t=36s

My setup is:
Arduino UNO
L293D Motor Shield
L293D Motor IC
Nema 17 stepper motors
GT2 10mm wide belt
GT2 36 teeth
Servo motor SG90
12v power adaptor

I have done the upgrade to the motor shield just like shown (solder one on top of the other). Everything is connected properly.
I am using Processing 2.2.1 to start the controller. I have set the machine and page dimensions, steps and mm per rev and updated machine spec (I get the C25,PGXXABCD,END error, but that does not seem to affect the machine).

The machine starts. I can set home and move the gondola accurately and I was also able to draw some vectors. The problem is while drawing the vectors the motors stop and start making a strange high pitch noise. I get the error: Powering down for no reason.

Please guide me in order to resolve this problem.

Please be aware that I have no knowledge of c++ or any language, but I can figure out anything if explained properly. Thank you!

cazkade
Newbie
Posts: 2
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Post Re: Powering down error
on: October 4, 2019, 14:38
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It seems that whatever it was it damaged the arduino. The Arduino gives an error when reuploading the code. I'm not sure about the L293D Motor Shield. I do not know how to test it.

I am thinking of rebuying the whole system, just to be sure. Do you know if the chips from the motor shield can be reused? Can they get fried?

sandy
Administrator
Posts: 1395
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sandy
Post Re: Powering down error
on: October 4, 2019, 16:12
Quote

Hi Cazkade, tricky to know what's going here, could be lots of things.

The biggest problem I ever came across with the L293D-based shield was that the motors, the power supply needed to be very closely matched to the L293D's capabilities - nothing is adjustable.

"Powering down" happens when the machine has been inactive for a set length of time (600,000ms = 10 minutes - see the code here https://github.com/euphy/polargraph_server_a1/blob/master/impl_uno.ino#L90-L99). That's designed to stop the machine from overheating and burning out driver chips. Holding the motors still, but at full power causes them to heat up, which lowers resistance, which allows more current to flow, which causes them to heat up, and so on. There's often a whining noise when the motors are held still and the whining changes frequency as the motor gets hotter.

The chips from the motorshield _can_ get fried, they can overheat. There is no thermal protection built into them. I think I'd be surprised if that caused the arduino itself to be damaged though, if it was wired up without the EXT_PWR jumper on the motor shield.

1. Does your arduino error happen when you have the bare arduino connected via USB? I mean, without having the motorshield attached? What error do you get?

2. Did the "Powering off" message happen after a long period of inactivity?

3. Which motors do you have?

4. Did you solder the piggy-backed L293Ds onto the ones below, or are they just push-fit?

sn

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