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Thread: Teensy 4.1 stepper motor library

  1. #1
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    Teensy 4.1 stepper motor library

    Hello, I need stepper motor library which is able to handle at least 300k steps per second(better 500k) for teensy 4.1
    Could you give me an advice, which library should I use? I found teensystep library, but looks like it is not compatible with teensy 4.
    Also which teensy pins should I use for step/dir, can I use any pwm for that?

  2. #2
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    300kHz is way fast for a stepper. What driver are you using that can go that rate? You can use any pwm pin for outputting to an external driver but a lot of the drivers show a max rate of 200 kHz.

  3. #3
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    Quote Originally Posted by PhilB View Post
    300kHz is way fast for a stepper. What driver are you using that can go that rate? You can use any pwm pin for outputting to an external driver but a lot of the drivers show a max rate of 200 kHz.
    3000rpm with x32 microstepping is > 300kHz step rate, many stepper drivers support x100 or x128 or even x256,
    although 3000rpm is very high for a stepper, unless running off high voltage supply.
    Tts rare to see a driver chip one that can handle that speed (I've used the DRV8711 before, max 250kHz).
    Industrial stepper-driver units are usually opto-coupled, further reducing the max step rate (30kHz might be typical).

  4. #4
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    Well, it's not actually a stepper motor, it is a servo drive, but control signals are the same.

  5. #5
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    Quote Originally Posted by MarkT View Post
    3000rpm with x32 microstepping is > 300kHz step rate, many stepper drivers support x100 or x128 or even x256,
    although 3000rpm is very high for a stepper, unless running off high voltage supply.
    Tts rare to see a driver chip one that can handle that speed (I've used the DRV8711 before, max 250kHz).
    Industrial stepper-driver units are usually opto-coupled, further reducing the max step rate (30kHz might be typical).
    Power drops off with microstepping. Going even to 1:16 drops the available power. I suppose there are some applications beyond that but don't expect to move anything very heavy. 3000 rpm is way high for a stepper. Probably better to use a DC motor.

    Most opto coupled stepper drivers are spec'd for 200 kHz - of the reasons I worked to push my grblHAL breakout board well above the old GRBL limit of 30 kHz.

  6. #6
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    Quote Originally Posted by addast View Post
    Well, it's not actually a stepper motor, it is a servo drive, but control signals are the same.
    OK, that makes some difference. You can generate very fast step signals though you might need to write your own code. 500 kHz is possible with some very tightly written code if you are not doing complex motion control. Problems arise when trying to continuously change the step rate for things like acceleration/deceleration, circles, arcs, polylines. Your code's "decision" time (how long it takes to determine the next step time) will limit your overall step rate. Also, you will need to handle error conditions (aka Alarm) if it looses steps.

    Now we get to main question - what is your application? Why do you need that step rate? What kind of accuracy and resolution do you need? If your paths are all predefined, then I would recommend you use GCode and a motion controller. Since I designed a breakout board for T4.1 grblHAL, I would use that but there are many possible solutions. Even if your paths are dynamic, you could still use a motion controller but would have to write a controlling program to feed it GCode.

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