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how to control stepper motors in laser projector

boraicho

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HI. I want to build my own laser projector with stepper motors. i want to use microprocessor, i know to write program in C, but i have a little problem. i don't know, how i have to do control stepper motors. I will be use unipollar stepper motor from 5,25" mechanics, 3,6° angle (yes, i know that is it a lot) and PIC MCU.
So, is there somebody, who know how it i have to do? thanks.
sorry for english.
 



SKeeZ

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it may take some major mechanical skills and some crazy tools to make such a projector. your C programing skills may be of no use in making a laser projector because steppers operate in G code, usually compiled by a program designed for the application. i suppose you may need to write a program in C that writes G code based on the shapes you draw in the program... it is a big undertaking to say the least. you may need to find someone with more experience in G Code compilers...

EDIT: I know there has to be an interpreter for the GCode... i would have to be stupid to think otherwise. mario suggested a good driver for them though.
 
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MarioMaster

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Steppers themselves don't know what Gcode is, that's just how most CNC based stepper motor systems operate.

Stepper motors themselves require turning on the coils in a specific order and correct polarity depending on what type of motors they are.

You should probably look into getting some purpose made stepper motor driver chips such as RepRap Stepstick Pololu A4983 Stepper Driver Compatible with A4988 Prusa Mendel | eBay

Then you literally just feed it two digital lines, one for steps and another for direction. Those little guys even do microstepping.
 

boraicho

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Hi, i'm already built laser projector with steppers motor but driver for motors i'm bought, but i want to build my own driver for stepper motor.
http://www.fastimages.eu/images/dsc034hyh.jpg
GreenLaserMAX - YouTube
with mechanics and electronics i don't have problems.
i know how to control motors but i do not know how to looks waveforms. and i don't know, what is G-code but i try to find it. Ok , right now miss me one motor but i will have him next week and then i will build construction.
 

Things

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I think in some of the cheap stepper projectors, they actually just run one of the coils constantly, so that the rotor has a bit of a "spring" to it. Then you can just power the other coils to make the mirror vibrate back and forth, as you don't need much movement at all.

This way would be a lot faster than just plainly driving the steppers.
 

123splat

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As per Mario, Forget about "G". Use whatever variant of "C" you are familiar with, and will compile to a hex file that PIC chips will understand. If you are good at C, you can look at some sample apps, available at Arduino.cc or sparkfun for how to structure the logic and adapt it to your C compiler.

As for Things' last post, good golly Miss Molly!! Never heard of that trick. The big problem suing steppers or Servo's has always been thier slow speeds. Good on ya, Things! and thanks.
 

boraicho

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hi. i did right now, this funny movie :yh: . I know how to control motor, but something is wrong. deflection of laser is very small and i don't know why is it so. maybe it is 1,8°deg but i don't believe.
(hm, i need second motor.)
stepasstep - YouTube
 

Bionic-Badger

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it may take some major mechanical skills and some crazy tools to make such a projector. your C programing skills may be of no use in making a laser projector because steppers operate in G code, usually compiled by a program designed for the application. i suppose you may need to write a program in C that writes G code based on the shapes you draw in the program... it is a big undertaking to say the least. you may need to find someone with more experience in G Code compilers...

EDIT: I know there has to be an interpreter for the GCode... i would have to be stupid to think otherwise. mario suggested a good driver for them though.

???

Wow! Not to belittle you here, but those statements reflect a serious disconnect in understanding the relationship of software and hardware! It's like believing saying you can only aim lasers in a projector by using QuickShow.

Do you even know what a stepper motor is, or what it does outside the context of CNC? What about a servo? Or just motors in general? This kind of knowledge helps one make the jump from being a mere technician to perhaps something more elevated like an engineer.

Check out the links MM provided. An understanding of the hardware itself is important in knowing how to use it. It'll make you more valuable, and flexible in your projects. Maybe you won't want to use something so high-level as G-code, because the interpreter hardware costs a lot, or is too slow, or even requires other software to produce. It's like being locked into some software like Multisim and its data acquisition hardware because you have no idea how to build something yourself. Will you force clients to buy that software because you can't create your own solution?
 

Bionic-Badger

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Sigh... this is what happens when people jump into something but ignore the basic foundation concepts.
 




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