Problem controlling a Stepper motor with AccelStepper

Question

I have an Arduino connected to a stepper motor with an Easy Driver as follows: enter image description here

I am controlling the position of the stepper motor using the Serial. This is my code:

#include <AccelStepper.h>
AccelStepper stepper(1, 9, 8);
void setup()
{ 
 Serial.begin(9600);
 stepper.setMaxSpeed(10000);
 stepper.setAcceleration(5000);
}
void loop()
{
 char c;
 if(Serial.available()) 
 { 
 int steps = Serial.parseInt();
 Serial.print(steps);
 stepper.moveTo(steps);
 }
 stepper.run();
}

The code works well but I'm facing a problem, when I set a high position value, it starts turning in the opposite direction, like if there was a limit on the steps. Does anyone know why it starts turning to the opposite direction?

I have tried to solve this problem by using:

if (stepper1.distanceToGo() == 0) 
 { 
 stepper1.setCurrentPosition(0);
 } 

so I can set lower values to the serial. But the problem goes back again when the value goes up to the power of 6 (like 1000000).

Any idea?

Thanks!

• dinotom: Per a comment from the developer of AccelStepper, the line AccelStepper stepper(1, 9, 8); should be written as AccelStepper stepper(AccelStepper::DRIVER, 9, 8); for clarity

Answer 1

Ints on vanilla Arduinos are 16 bits, and signed, which means they hold values from -2^15 to +2^15-1, so of course you cannot assign 10^6 to one of them. Use unsigned long (4 bytes), or, better yet, specify the length explicitly by using uint32_t.

• Alvaro: could you post me the reference of this?
• JayEye: This has always been the case for 16-bit processors. Plus, it's in the adruino documentation. Plus, you can verify it for yourself by writing a one-line program.