Servo goes down at the beginning of every run

[jvolker]

The servo goes down at the beginning of every run drawing a dot at [0,0]. Is there a way to prevent that?

Thanks.

[arnaudjuracek]

I did some research, and it appears that the problem is linked to the way the Arduino servo library works (1, 2, 3).

At the beginning of every run the serial port is opened, which mean that the plotter's board is reset and setup again, calling servo.attach(), which in turn setup the servo, drawing a dot.

I never encounter this problem on my personal setup because the [0,0] is usually outside the canvas. You might want to try to disable the servo setup as mentionned in the SO answer [1].

[jvolker]

Thanks.

I've now solved it by doing what is suggested in 2.

I changed the following lines in setup() from:

  servoPen.attach(servopin);
  delay(100);
  servoPen.write(servo_position);
  delay(1000);

to:

  servoPen.write(servo_position);
  servoPen.attach(servopin);
  delay(1000);

You might want to try to disable the servo setup as mentionned in the SO answer [1].

That didn't work, unfortunately.