Shop OBEX P1 Docs P2 Docs Learn Events
Boe Bot won't go forward — Parallax Forums

Boe Bot won't go forward

mrdubyamrdubya Posts: 2
in General Discussion
I am having an issue with my Boe Bot. The program I have written should make the robot go forward, but all it does is spin in circles. The Servos are installed correctly, and the program is written correctly (I've checked and rechecked both of these things). It did this the other day, and I thought I fixed it by unplugging the servos and plugging them back into the Board of Education, and it worked. However, I noticed today that the issue came up again, and I can't seem to correct it.

Anyone have any answers or places to look?

Thanks!

Comments

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    The most likely cause of this is uncalibrated (centered) servos. One of the first things you do before installing the servos is center them. This happens by sending a 750 pulse to the servo and adjusting the screw until the servo is not moving. I have noticed quite a few people skip this step and install the servos without having done this. It often results in what you're describing. So I would recommend run the centering code and going through those steps.
  • mrdubyamrdubya Posts: 2
    Okay, so I calibrated the servos and they were properly calibrated. But I discovered an interesting problem in the process. When I wrote the program "pulsout 13, 850", both servos ran in the same direction, even though I never wrote anything about 12. When I wrote "pulsout 13, 650", both servos ran in the same direction as one another, again, just in the opposite direction as they were previously. What would be causing that?
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    This indicates a short between your P12/P13 I/O pins.
  • ercoerco Posts: 20,256
    edited 2016-03-01 22:17
    You sure it's an electrical issue? That seems unlikely, check your wiring against the book diagrams.

    First timers often get the spin problem you describe when they send the same pulse to both wheels, either 650 or 850 to both, thinking that will go straight. But in reality you need to send a 650 to one and 850 to the other, since they face in opposite directions. You need one to rotate clockwise and the other counterclockwise to move straight.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    Erco, the OP says code written to drive only one I/O pin is moving both servos.
  • ercoerco Posts: 20,256
    @chris: I saw that, I just didn't believe it. Since mrdubya is a new poster, my money is on a connection or programming issue. Unless of course, shorted P12/P13 pins is a recurring issue.

    @Mr W: Welcome to the forums, we are eager to help you out. Please post the exact code you are using so we can help locate the problem. If possible, please attach a closeup photo of your servo connections to the BoE.

Sign In or Register to comment.