Motor coils remain energised

I’ve just finished building a v7 alpha2 with pi optics.

Motor control is using a nano clone flashed with sangaboard firmware v0.5.1 and uln2003 diver boards.

All motor movement works as it should but when the move has been completed there are always 1 or 2 of the LEDs on the corresponding control board lit. Presumably this means there is still power going to those motor windings. Motors also feel fairly hot to the touch.

Is this deliberate to lock the motors in position or is it faulty behaviour?

The motors are deliberately held energised, as you say this is to keep the position locked. The motor current should be quite low and the motors should not get hot. However some batches of this type of motor seem to draw a lot more current and some can get very hot indeed. There are other threads here with more discussion of problem motors. Keyboard shortcuts and motor temperature - Request Help - OpenFlexure Forum , An absolute position encoder for the Openflexure Microscope - Contributions - OpenFlexure Forum, How to configure/use sangaboard? - Request Help - OpenFlexure Forum.

My motors barely get warm, so it sounds as though yours are hotter, but not at the really hot end of the range.


There is a command in the Sangaboard firmware to release the motors - as William says, this probably hurts repeatability, but if you don’t particularly need to return to the same coordinates, it might help a lot with heating.

I am not sure this is exposed via the web API and it’s definitely not in the interface - but it would be possible to add in the future if it would help enough people…


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The same happens to me.
The motors work, (using the controls) but get very hot to the touch.
I couldn’t find a reason, so I just powered it down.
It is now a conversation piece.
I will try your suggested links.

Very hot to the touch is hotter than many/most are, even powered on all the time. It would be useful if you were able to measure teh current on the 5V motor supply. When I measured it was a bit less than 0.6A.

I would certainly be happy to sacrifice repeatable positioning for less heat in my motors. Would be great as an option in the interface.

Hello William,

Thank you for your reply.
I will measure the amps of every motor,
And will get back to you.


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