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Topic: 28BYJ-48 question (Read 3041 times) previous topic - next topic

nass

May 14, 2013, 10:56 pm Last Edit: May 15, 2013, 12:08 am by nass Reason: 1
Hello,

I've just 'graduated' from the starter kit so I'm pretty clueless, but branching out and experimenting with a few different things for a device I want to build, which includes steppers. So I bought this 28BYJ-48 stepper and hooked it up as below using the sketch below, from Adafruit. Works great!

I don't get something though, it takes an input value of 2048 to make it go round once. Can anyone explain please how this relates to its specs (Step angle: 5.625 x 1/64. Reduction ratio: 1/64) or the sketch? At Adafruit it states a value of 500 should turn it once... different motor or have I been a bit of a muppet between the sketch and the circuit somewhere?

Thank you


circuit:


sketch:
Code: [Select]

/*Adafruit Arduino - Lesson 16. Stepper*/
#include <Stepper.h>

int in1Pin = 12;
int in2Pin = 11;
int in3Pin = 10;
int in4Pin = 9;
Stepper motor(512, in1Pin, in2Pin, in3Pin, in4Pin);  

void setup()
{  
  pinMode(in1Pin, OUTPUT);  
  pinMode(in2Pin, OUTPUT);  
  pinMode(in3Pin, OUTPUT);  
  pinMode(in4Pin, OUTPUT);  
  while (!Serial);  
  Serial.begin(9600);  
  motor.setSpeed(30);
}

void loop()
{  
  if (Serial.available())  
  {      int steps = Serial.parseInt();    
         motor.step(steps);  
  }
}


MarkT

Ah, I remember playing with this stepper, I believe it takes about 4096 _half_ steps to go round.  If you use full-steps
it takes 2048 (approx), which corresponds to 512 full sequence cycles per revolution.

I say approx because the gear ratio isn't actually 64:1.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

nass


terryking228

Hi, there is added info / example software here:  http://arduino-info.wikispaces.com/SmallSteppers
Regards, Terry King terry@yourduino.com  - Check great prices, devices and Arduino-related boards at http://YourDuino.com
HOW-TO: http://ArduinoInfo.Info

sbright33

Terry, do your motors have exactly 4096 half steps?  I can't remember where I got mine, and people are asking.

terryking228

Quote
Terry, do your motors have exactly 4096 half steps?


Hmmm. I ASSumed they did based on Other Stuff I Read.

That's not the same as Knowing.  I think I just sent my last in-USA sample to someone; I'll get more soon, and my reaction is to test them with multiple resolutions (like does it return exactly with 40960 steps?? 

I also may tear one apart and count teeth??  Anyone done that? 

The stated Gear Reduction on the specs I see is 64:1 so 360/5.625=64 steps per revolution on Internal Motor.  And 64*64=4096 steps per output shaft revolution.

Hmmm.... Needs to be Proofed..
Regards, Terry King terry@yourduino.com  - Check great prices, devices and Arduino-related boards at http://YourDuino.com
HOW-TO: http://ArduinoInfo.Info

sbright33

Some motors are 4096 exactly, others are 4075.123 or something.  Not very convenient.

sbright33

Still no word Terry?  I have some 4096 motors, but I'm not sure where I got them.

MarkT


Some motors are 4096 exactly, others are 4075.123 or something.  Not very convenient.



Strong suspicion they are made as cheaply as possible to a common specification with low accuracy
requirements - the original purpose is controlling air-vanes in car air-conditioning systems I believe,
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

terryking228

Hi, I just got 5 more of these in to test with here is USA and I'll try to get to some testing.

Hmmm. I don't believe any of these can have a factor that is not the product of two integers.. they ARE just teeth, right??

So funny numbers make me strongly suspect some dropped pulses.

I need to prototype a small robot using these Real Soon Now....
Regards, Terry King terry@yourduino.com  - Check great prices, devices and Arduino-related boards at http://YourDuino.com
HOW-TO: http://ArduinoInfo.Info

scottyjr

Quote
I also may tear one apart and count teeth??  Anyone done that?


Although I cannot find the post now, someone had and posted images of rather odd gearing. - Scotty

sbright33

Yes, but some are 4096, some are 4075.  BOTH EXIST. 
I'm am curious about Terry's motors specifically because he is selling them!

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