My First geeky YouTube video

9 April, 2008

It’ll be video podcasts next ;-)

[YouTube=http://www.youtube.com/watch?v=HRzqh8Hb4xk]
YouTube – Unipolar stepper motor controller PCB with serial input

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Committed to a PCB

6 April, 2008

So here is the unipolar stepper motor controller committed to a PCB. It’s my first PCB that I’ve made and populated from scratch. I used the toner-transfer method and then drilled out the holes with a small drill. I’ve got a programmer on there so I can upgrade the firmware if needed. The connector for power and a serial command is a bit of a hassle at the moment but will fit in with my grand scheme! Note: this need regulated power, which I’m assuming will come from a master board (the supplier of the serial). This makes sense as I’ll have multiple (modular) controller boards.Unipolar stepper motor controller PCB


PICAXE unipolar stepper motor controller

8 March, 2008

Here’s my stepper motor controller, based on an 18 pin PICAXE microcontroller. The idea is that this chip takes away the processing overhead associated controlling a stepper. A master CPU (of some kind, potentially a PC) can send a serial command to the PICAXE telling it how much to move and at what speed (and direction). A Darlington driver array controls the power and a 7-segment display shows the current coil powering. Here’s the schematic (PICAXE programming connector not shown):

schematic

The way I’ve programmed this is different to other approaches I’ve seen. These tend to complete a full rotation every time. I’m sure others have done controllers that manage sub-rotation control like this but maybe not the way I’ve done it. I basically have a single value which defines how far the motor has rotated. I then increase this number step wise and use modulo division (//) to find out what position the rotor should have.

Program and video of operation after the break…

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