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Problem with Stamp BOE — Parallax Forums

Problem with Stamp BOE

ajwardajward Posts: 1,130
edited 2013-02-18 17:11 in Robotics
Hi all....

I was working with one of my 'bots controlled with a Stamp BOE and ran into a problem. Any servo connected to servo header 15 runs in the same direction, at the same speed no matter what command I send to it. I'm not sure what might be causing this... Could the Stamp module be damaged? Any way I could have damaged the board?

Any advice would be appreciated!

Amanda

Comments

  • PJAllenPJAllen Banned Posts: 5,065
    edited 2013-02-16 09:51
    Do you have another Stamp that you could swap out?
    It's just a trace from "P15" to that header.
  • Martin_HMartin_H Posts: 4,051
    edited 2013-02-16 10:10
    That is really weird because a dead pin usually doesn't do anything, let alone pulse a servo properly.

    I keep an LED soldered to a resistor handy for this sort of situation. I would disconnect the servo and upload a pin 15 high / low program and test the output with the LED. If that works I would then connect a switch to the pin with some resistors to limit current and test the pin as an input. If that works I would use a DMM to test continuity and voltage at the header.
  • ercoerco Posts: 20,256
    edited 2013-02-16 12:15
    Something is hinky. The same servo works properly on the other headers? Jumper set for Vin or Vdd? Use jumper wires and hardwire it to the socket left of breadboard.

    Battery good? :)
  • Martin_HMartin_H Posts: 4,051
    edited 2013-02-17 12:43
    I'm dying of curiosity. Any progress on this problem?
  • ajwardajward Posts: 1,130
    edited 2013-02-17 22:37
    Martin_H wrote: »
    I'm dying of curiosity. Any progress on this problem?

    Working on it in the morning. Been a very lazy weekend. I'll let y'all know asap. And thanks for the input!!!!!!

    Amanda
  • ajwardajward Posts: 1,130
    edited 2013-02-18 09:07
    Marked "Solved". Mostly solved anyhow.

    I swapped another Stamp into the BOE and everything worked as it should. Then I put the suspect critter into another BOE and the problem reared its ugly head.

    So, I guess the problem with the servo is solved, but I don't understand what happened to the Stamp. Between the time it was working and the time it stopped, the only thing that changed was the date... same battery, same program.
    Nothing lasts forever, eh?

    Amanda
  • ercoerco Posts: 20,256
    edited 2022-04-12 20:03
    It's possible that particular pin got zapped somehow (static, overcurrent) and yet it might still function as as input. Hopefully your other 15 pins are still good. Check 'em out. See Tracy Allen's ingenious Stamp test program at https://forums.parallax.com/discussion/comment/930555/#Comment_930555
  • Martin_HMartin_H Posts: 4,051
    edited 2013-02-18 09:36
    Amanda, well it is good you understand it, but sorry to hear it was the BS2 pin.
  • ajwardajward Posts: 1,130
    edited 2013-02-18 16:05
    Another question. I understand Stamp programming, to an extent, but the hardware... not so much. I set up the questionable Stamp on a carrier board for testing to see what works and what doesn't.

    A program to toggle an LED on Pin 15 sort of works. If I set up the hardware so the Stamp supplies VSS to the LED circuit, it works. If I reverse it so the Stamp supplies VDD, it doesn't. Does this seem reasonable? Can a bad pin not go High or not go Low? Floating between both in some state?

    Just trying to understand what the module is up to. :-)

    Amanda
  • Martin_HMartin_H Posts: 4,051
    edited 2013-02-18 16:14
    A crazy guess, but the stamp might be able to sink current, but not source it. Do you own a DMM or oscilloscope? You might want to measure the pin voltage when you have it high versus low state.
  • ajwardajward Posts: 1,130
    edited 2013-02-18 16:33
    Martin_H wrote: »
    A crazy guess, but the stamp might be able to sink current, but not source it. Do you own a DMM or oscilloscope? You might want to measure the pin voltage when you have it high versus low state.

    Sure Martin, on both items... a project for tomorrow. Engrossed in watching the sci-fi flick "Reptilicus" right now. Another of the things that can grab my attention. :-)

    @ - Wishing I knew the workings inside this beast! Edit: Not the movie beast!
  • Martin_HMartin_H Posts: 4,051
    edited 2013-02-18 16:35
    ajward wrote: »
    Sure Martin, on both items... a project for tomorrow. Engrossed in watching the sci-fi flick "Reptilicus" right now. Another of the things that can grab my attention. :-)

    I'm glad you have your priorities in order. I love the movie Reptilicus!
  • WhitWhit Posts: 4,191
    edited 2013-02-18 17:11
    Thanks for the link to Tracy's test program erco!

    Glad you are on the road to a solution ajward...
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