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BOE-Bot Movement @ Start — Parallax Forums

BOE-Bot Movement @ Start

Hello.

When the power is turned on and/or reset button pressed with my student's BOE-Bots (we use Arduino microcontrollers) there is an initial movement of the wheels caused by (my best guess) a power surge possibly. Is there a way to keep the BOE-Bot from moving from this initial surge from turning the power on and/or pressing the rest button?

Thank you.

Comments

  • This happens on all BOE-BOTs? What happens when the power switch is set to 2, reset, then switch to 3?

  • @Publison said:
    This happens on all BOE-BOTs? What happens when the power switch is set to 2, reset, then switch to 3?

    Good call....the switch is labelled 0-1-2 so I had my students try setting to 1 and pressing reset and quickly setting to 2 and there is no movement. For the time being looks like that's the fix but just wondering where this surge is coming from when the power switch is at 2 and reset button is pressed. Thanks for the reply!

  • kwinnkwinn Posts: 8,697

    Sounds like a design problem that I have come across on several types of equipment where the signal to the motor powers up in the on state and the microcontroller then sets it to the off state a short time later. Sometimes this can be fixed by a pull up or down resistor.

  • @johnhammons said:

    @Publison said:
    This happens on all BOE-BOTs? What happens when the power switch is set to 2, reset, then switch to 3?

    Good call....the switch is labelled 0-1-2 so I had my students try setting to 1 and pressing reset and quickly setting to 2 and there is no movement. For the time being looks like that's the fix but just wondering where this surge is coming from when the power switch is at 2 and reset button is pressed. Thanks for the reply!

    Sorry. I meant 1 first, then reset, then sent to 2.

  • @kwinn said:
    Sounds like a design problem that I have come across on several types of equipment where the signal to the motor powers up in the on state and the microcontroller then sets it to the off state a short time later. Sometimes this can be fixed by a pull up or down resistor.

    Tell me more please....any pic of a breadboarded circuit you have handy to show me the layout perhaps?

  • johnhammons,

    Check the batteries.

    Assuming it was working correctly before, the batteries are probably weak.
    Servos are power hungry little monsters.

  • kwinnkwinn Posts: 8,697

    @johnhammons said:

    @kwinn said:
    Sounds like a design problem that I have come across on several types of equipment where the signal to the motor powers up in the on state and the microcontroller then sets it to the off state a short time later. Sometimes this can be fixed by a pull up or down resistor.

    Tell me more please....any pic of a breadboarded circuit you have handy to show me the layout perhaps?

    Sorry, I don't have any circuits or breadboarded circuits with that problem. I saw it in the early days of microcomputers when they were first being used for controlling mechanical systems like pipetters, sample conveyors, and such. Post some pictures and the schematics of the BOE-Bot and Arduino and I will see if I can suggest a fix.

  • ercoerco Posts: 20,195

    Many servos glitch on powerup, especially if there is no control signal present. Per Publison, the safest route is to fire up the BS2 first on switch position 1, then power up servos using switch position 2.

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