I have some electrical knowledge but that can be more dangerous than good when it comes to tinkering. I am attempting to wire up a simple 4 pin bipolar CDROM stepper motor to an arduino Uno through a DRV8825 stepstick.
Questions are as follows...
1. How does voltage/amperage work and how to I test this?
I started with a wall wart power supply which read 12V / 800ma but my volt meter shows closer to 18V. I do understand that these things tend to have tolerance levels within a given range but don't know how that might affect my results.
So far.... :
I believe that everything was wired to my CDROM drive bipolar stepper correctly and although I was able to actuate the motor and get it to travel back and forth there was a buzzing noise and the motor began to heat up quite a lot. (Note: I do not know the stepper motors specs but I do know continuity of the poles so I at least have As and Bs - although it is possible that I have B1/B2 mixed up. I don't know how I'd tell the difference )
I have another PS but it's larger. It's a 12V / 1.5A (measures at 11.92V on my meter) which sounds closer to working for my stepper but I'm concerned about the higher amperage. Is that an issue? Will my stepper draw whatever is 'offered' or is the 1.5A just a limit in what could be drawn. Do you think it's safe to swap out my P/S units or is that a bad idea?
2. How does the trimpot work? What/how do I measure?The DRV8825 has a small trimpot which can be used to control the current. (left is lower / right higher). I'm wondering f this might be useful to me as well (and how I'd test that. My multimeter does have 20A and mA sockets for the leads but I've never used them to test anything)?
What makes the most sense is to remove the motor and test what voltages / mA I get at A1 A2 B1 B2 and ensure its within some sort of range that my motor would likely handle (sorry there are no marking on it)
My best guess right now is that I'm looking to inject the close to correct voltage/current so that the motor moves but doesn't make funny noises or get excessively hot.
While I don't have the arduino code in front of me my basic setup uses three pins (4,5,6) on the Uno to control the driver....
DIR - PIN4
STEP - PIN5
SLEEP / REST / M0/M1/M2 - Bridged to 5V line (I believe this is 1/32 step)
Enable - PIN6
Any thoughts or suggestions on how I troubleshoot what I've got before I manage to fry something would be appreciated.
If useful I can include images and the code from my other PC that's running the Uno board.
Thanks.Statistics: Posted by wirelessguyny — Mon Jul 13, 2015 12:13 pm
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