I have attached photo of the setup. I am using the stepper_speedControl sketch from the Arduino software examples. I am using a wantai stepper motor 42BYGHM809. The power source is a wall wart 12V 2A DC and I have tried using 8 AA batteries but same problem.
The motor doesn’t follow the speed maped by the potentiometer and changes direction when the value is close to zero. But when I put my finger under the three pins (RX, TX and Pin 2) the motor seems to be running fine and perfectly mapping the speed defined by the potentiometer.
Motor Details: http://www.wantmotor.com/ProductsView.asp?id=157&pid=75&sid=80
Sketch:
/*
Stepper Motor Control - speed control
This program drives a unipolar or bipolar stepper motor.
The motor is attached to digital pins 8 - 11 of the Arduino.
A potentiometer is connected to analog input 0.
The motor will rotate in a clockwise direction. The higher the potentiometer value,
the faster the motor speed. Because setSpeed() sets the delay between steps,
you may notice the motor is less responsive to changes in the sensor value at
low speeds.
Created 30 Nov. 2009
Modified 28 Oct 2010
by Tom Igoe
*/
#include <Stepper.h>
const int stepsPerRevolution = 200; // change this to fit the number of steps per revolution
// for your motor
// initialize the stepper library on pins 8 through 11:
Stepper myStepper(stepsPerRevolution, 8, 9, 10, 11);
int stepCount = 0; // number of steps the motor has taken
void setup() {
// nothing to do inside the setup
}
void loop() {
// read the sensor value:
int sensorReading = analogRead(A0);
// map it to a range from 0 to 100:
int motorSpeed = map(sensorReading, 0, 1023, 0, 100);
// set the motor speed:
if (motorSpeed > 0) {
myStepper.setSpeed(motorSpeed);
// step 1/100 of a revolution:
myStepper.step(stepsPerRevolution / 100);
}
}
