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Joined: Wed Sep 13, 2017 10:58 pm

Scrap Stepper Motor

Wed Sep 13, 2017 11:25 pm

Ok, be gentle. I've just started using the Raspberry Pi and have gone through RFID Starter Kit Tutorial, which was really well put together. Now I want to move onto driving a scrap stepper motor. So I went to the scrap yard and picked up an HP LaserJet P3005x printer and pulled a Mitsumi stepper motor M55SP-2K out of it with the following spec sheet:


Rated Voltage DC 24
Working Voltage DC 21.6 - 26.4
Rated Current/Phase 0.8 A (Peak) 1.2 A (Peak)
No. of Phases 2 Phase
Coil DC Resistance 5 Ohm/phase +/- 10%
Step Angle 7.5 deg/step
Excitation Method 2-2 Phase excitation (Bipolar driving)
Insulation Class Class E Insulation
Holding torque 156mN.m 200mN.m
Pull Out-Torque 101mN.m/800pps 154mN.m/800pps
Pull In - Torque 167mN.m/200pps 168mN.m/200pps
Max Pull Out Pulse Rate 3000 pps 1750pps
Max Pull In Pulse Rate 350ps 390 pps

My understanding is that I need a driver with a separate power supply. Is there anybody out there that has had some success driving this motor or something similar with a Raspberry Pi 3? If so any help would be greatly appreciated.


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Re: Scrap Stepper Motor

Thu Sep 14, 2017 1:27 am

I would suggest to get the most commonly used stepper motor driver used for small to medium stepper motors the DRV8825 then google "raspberry pi DRV8825 tutorial"

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Re: Scrap Stepper Motor

Thu Sep 14, 2017 7:58 am

That will do well - I've done the same thing using a pololu a4988 drive carrier, which is very similar. I would just add that some (if not most) HP printers also have nice separate power supplies in them which you can use to power both the stepper and the raspberry pi if it has a 5v output as well.

I use pigpio and some home brew python to drive various steppers - it is not trivial if you want to drive them at full speed as they need to be ramped up and down if you want to maintain accurate positioning and pulse timing needs to be accurately maintained. Even C code won't reliably drive them at full speed due to OS scheduling and interrupts.

pigpio provides a facility (waves) which allows you to prepare pulse trains in advance and it then uses DMA to drive the gpio pins, resulting in very accurate timing to be maintained.

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