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Strange behaviour of PSC servo controller — Parallax Forums

Strange behaviour of PSC servo controller

inakiinaki Posts: 262
edited 2005-04-11 23:07 in Robotics
I have observed the following beahavior in the PSC (firmware version 1.3).
When the battery is going down (let say, about 15 minutes of work -yes 15-)·the motors stop completely, that is to say, they are no more under control.·Some minutes before this happens the servos·'rattle' a lot. While there is rattle the motors are still under control. This last for about 5 minutes.·Then silence and no more control.

This might seem normal but, then I·disconnect the motors from PSC, and connect them to another servo controller,· a Seetron serial controller. Without charging the same·batteries I can operate the motors normaly for about 20 minutes more!

What is going on here ? Why motors stop working under the control of PSC but continue to work if I change the controller ? Is there any software thing behind ?

Thanks for your comments.
Inaki.
·

Comments

  • JonbJonb Posts: 146
    edited 2005-02-18 20:57
    Hi, I also have a PSC.

    Servos can draw alot of power from batteries. When a battery is left to rest for a few moments(depends on battery type) they can appear to regain energy. The chemicals stabilise in the battery and more juice can then be pulled wink.gif·This could also be simulated with a flashlight or many other battery operated devices including cell phones.

    Post Edited (Jonb) : 2/18/2005 9:00:32 PM GMT
  • eflyefly Posts: 34
    edited 2005-04-06 18:20

    ······· Hi all, here is another question about the PSC, I have experience twice that I cannot detect ·Stamp Board· after connect to PSC, I check the wires connection are correct because ·I can run the servo previously and ·never disconnect the wires, then I realize the PSC board is very hot and malfunction , so at last what I only can do is buy a new PSC to continuous my robot project. ··
    ·
    ·······Is that anyway to avoid this “accident” since I already sacrifice two PSC but still don’t know what is the behind reason.

    · cry.gif
  • AlexAlex Posts: 20
    edited 2005-04-06 20:43
    ·Make sure you have revision C·of the Parallax Board of education as the older boards do not work

    with the PSC and will cause failure of the PSC controller.



    Alex
  • eflyefly Posts: 34
    edited 2005-04-07 02:34
    Yes, thanks Alex, I am ·currently using ·revision “A”·of the Parallax Board ……. I thought there is not important because the user manual never say cannot using Rev A or B of the Stamp Board……·····
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-04-07 03:36
    efly,

    ·· Actually you can use any of the BOE boards regardless of revision.· What you have to make sure of is that you are not powering the PSC with more than 5VDC.· This means do not connect it to the Vin line for voltage.· You must use the Vdd line to power it.

    ·· Also be sure all 3 lines from the BOE are connected properly to the PSC.· The GND line should be connected to Vss/Ground on the BOE.· The +5VDC line should be connected to the BOE Vdd line, and the Signal line should be connected to an appropriate Stamp I/O pin.

    ·· Be sure to follow the code examples carefully that come with the PSC, and are also available on our website.· I have tested this configuration here and it works.



    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • AlexAlex Posts: 20
    edited 2005-04-08 23:34
    Hmmm...We have tried non rev C BOE boards of which the same results happen..an overheated and fried PSC. We use seperate power for the PSC and simply conect the PSC to the BOE via the X15 port. Non Rev C boards it heats the PSC, Rev C boards all works well.·What gives in this scenario?



    Thanks,



    Alex
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-04-09 02:00
    Alex,

    ·· Well, not sure what X15 connector you're talking about.· The BOE Rev B & C·has X4 and X5 which servos normally plug into.· Rev A does not has these connectors, so I'm not sure where you're plugging them in that's making them heat up.

    ·· Assuming it's the X4 or X5 sockets on the BOE Rev B, then that is why.· Rev B boards have the X4 & X5 power coming from Vin.· This is normally for the servos themselves, which will run on the 6 volts from the battery pack, but but depending on what you're powering the BOE from it will be too much for the PSC, which only runs on 5VDC.

    ·· On the Rev C boards we added a jumper so you could switch between the Vin & Vdd for the X4 & X5 sockets.· This makes it more flexible, but you can still destroy your PSC if you have the jumper in the wrong position and apply too high a voltage to the BOE.··I hope this messages helps anyone who has made these mistakes, or at least prevents anyone else from making them.



    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • AlexAlex Posts: 20
    edited 2005-04-11 23:07
    Chris:

    Thanks. I meant the X5 port. Sorry. Your explaination sounds correct!

    Thanks,

    Alex
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