Running hardrive motor with Raspberry pi

[sci143]

Hi everyone,

This is my first post here, so please excuse me for naive questions.

Is it possible to control speed of a hard drive motor using Raspberry Pi/Arduino, without using extra electronic components such as motor driving ICs. Something like below video, but I dont want to use any extra components, except USB plug.

https://www.youtube.com/watch?v=CMz2DYpos8w

Also, is it possible to measure the back emf or simple USB conection or just using GPIO pins of raspberry Pi.

If there is any such tutorial, could you please point me. I have tried different search words, but was not successful.

Many thanks in advance.

[fzabkar]

You might like to read the L7250 datasheet.

http://pdf.datasheetcatalog.com/datashe ... Xyuswx.pdf

The L7250 is a motor controller IC, but the datasheet discusses how it drives the motor.

[sci143]

Hi Fzabkar,

Many thanks for your reply. Although the pdf is explaining about the L7250's functioning and how it results in sinusoidal steps, I am not able to get a hints of using it with Raspberry Pi. If anyone has done this project, please help me.

[fzabkar]

The Youtube circuit drives each phase in turn. I would use a CRO to monitor the collector/drain of the Darlington/MOSFET driver to see how the voltage behaves when the transistor is switched off. Then you could square it up with a comparator and/or Schmitt trigger and feed it to your GPIO pins.