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Servo port 12 stopped working... — Parallax Forums

Servo port 12 stopped working...

henry151henry151 Posts: 8
edited 2009-08-15 12:43 in BASIC Stamp
What could cause one of my servo ports to stop working? I have checked the servo, its fine.

Using BasicStamp2 + BOE

Any help would be welcome.

Henry.

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2009-08-15 02:48
    There might be a bad connection somewhere between the servo cable and the Stamp I/O pin. It is theoretically possible to burnout an I/O pin, but it's not easy to do. You'd have to accidently connect the I/O pin to a source of voltage well above +5V or well below 0V. You can also damage an I/O pin by drawing too much current into or out of the pin (> 25mA typically). I don't know if connecting a servo backwards (with the plug reversed) would do it, but Stamps are fairly tolerant to this.

    Try making a connection between the servo plug and the breadboard area on your BOE with jumper wires inserted into the servo plug and the other end into appropriate power and I/O pin sockets around the breadboard.
  • henry151henry151 Posts: 8
    edited 2009-08-15 02:58
    Thanks a lot, great info!

    I am using a 7.2v power supply (6 AA NimH), with the servo jumper set to Vin.

    [noparse]:([/noparse] think I may have fried it.

    I was under the impression that the servo's could handle upto 7.5v and that the BOE regulated power to 5v for the breadboard. This is a BOE Bot and port 12 is the main drive right servo.

    I will test, but is it possible this has damaged the BS2 chip itself, or just the board?
  • Mike GreenMike Green Posts: 23,101
    edited 2009-08-15 03:13
    Servos generally are ok with a 7.2V supply. Supply voltages over 6V tend to modestly shorten servo life since the motor brushes tend to arc more, but it's not a big deal.

    Just using a 7.2V supply and running the servos off that (as Vin) shouldn't cause problems.
  • henry151henry151 Posts: 8
    edited 2009-08-15 12:43
    Pin 12 appears to be High all the time now, thats the servo port and the breadboard.
    I think thats the BS2 chip fried then.

    What I really need, is to find out how this happened, so I don't blow any more chips in the future.
    Why pin 12? Its only ever had a Parallax Servo connected.

    Hmmm, forgot I had Vservo going to the breadboard for an extra servo, but it was connected to pin 11.

    Still don't know how this happened. I am reluctant to continue my development project untill I know exactly what occured.

    How can I use Vservo to power another servo, without using the servo ports (ie, directly connected to breadboard)??

    Post Edited (henry151) : 8/15/2009 11:29:42 PM GMT
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