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Parallax Servo Controller "freezes" — Parallax Forums

Parallax Servo Controller "freezes"

bulkheadbulkhead Posts: 405
edited 2006-12-06 06:03 in Robotics
I'm using a USB PSC with a javelin stamp on my robot. I found that my PSC "freezes" and stops sending signal to my servos under certain conditions. These conditions occur when I drive around in a certain way, then do a series of tasks. Out of order, everything works fine, but when I do everything in this particular order it "freezes."

It isn't my javelin because it still runs when the PSC stops. I've tried adding more delays in the code in the part where this occurs, but nothing is any different. I've tried recharging both my battery packs, 7.2 V for the javelin (and the javelin's +5V for PSC logic) and 6.0V for the servos.

One possibility that I have come up with is that the current the servos are drawing is too much for the PSC? I'm running 9 servos total, 6 of which are high torque (Hitec 5645MG's). Everything ran fine a few days ago before I added the 9th servo, but that was just a mini servo.

I can't think of anything else right now, if anyone has any ideas that I could try, please post them. Thanks.

Comments

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-12-04 04:35
    Hello,
    ·
    ·· If you remove the 9th servo and resort back to previous code does the problem go away?· What about if you just disconnect the 9th servo and use the current code?· This might help narrow down a code issue versus a hardware issue.

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    Chris Savage
    Parallax Tech Support
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2006-12-04 05:23
    IMHO, it is very common to have the motors divert power from any microprocessor.
    Bulkhead - It sounds like you identified the problem
    Generally when using soo.... many motors, one should consider separating the supply to the motors from the control.
    When there is a power drain, the voltage drops and micro begins to loop through low voltage resets.

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    "If you want more fiber, eat the package.· Not enough?· Eat the manual."········
    ···················· Tropical regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
  • bulkheadbulkhead Posts: 405
    edited 2006-12-06 06:03
    Well, it's strange but today it seemed to work fine. No locking up of any sorts. Until it happens again, I won't be able to disconnect some servos to see if it is a current overload.

    However, I am currently using two battery packs, one for my javelin stamp's logic (which powers the PSC's logic) and another just for the servos. I don't see how a spike in servo current can affect the logic power supply. Unless the PSC has circuitry to protect itself from too high current? I guess I will have to see
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