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Baffled — Parallax Forums

Baffled

ArchiverArchiver Posts: 46,084
edited 2001-04-24 21:02 in General Discussion
I have this little problem with my robot. It is supposed to be a BOE-bot type
robot. I have everything working except the servos.
Basically the BS2 drives/reads 2 IR LEDs, one IR detector, an LCD, and 2 servos.
The LCD is to display what direction the BS2 is intending to go.
When I hook up everything the 'bot goes back and to the right. but when i
remove the ground from the servos the 'bot works fine. Also i have tried
starting the bot with the servos on and then remove the power and apperently it
only matters what state the servos are in (on/off) when the BS2 starts the
program, (ie if the servos are on when the BS2 starts and they are turned off
afterward the BS2 still acts funny). I also have a 2200uF cap across the
servo's power supply, which is different from the BS2's power supply.

I have no idea as to what might be causing the problem. I was thinking of adding
an optoisolator to the servo input but haven't got around to it yet.

Thanx
Seth

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2001-04-23 21:30
    Might try a 330 ohm resistor between the stamp pin and the servo. This was
    recommended elsewhere when I was playing around with servos. Also, are you
    running the I/R LED's off the stamp power? When I added one more I/R LED to
    my BS1 line follower (also running two 5-volt relays) it acted flaky. Rigged
    the LED's to run off the 9-volt battery and the problem went away.

    As far as the servo power, I had problems using a different power source
    also. Not sure what caused it, but when I built my own board with a 5-volt
    regulator and ran everything off it, they worked fine.

    Original Message

    > I have this little problem with my robot. It is supposed to be a BOE-bot
    type robot. I have everything working except the servos.
    > Basically the BS2 drives/reads 2 IR LEDs, one IR detector, an LCD, and 2
    servos. The LCD is to display what direction the BS2 is intending to go.
    > When I hook up everything the 'bot goes back and to the right. but when i
    remove the ground from the servos the 'bot works fine. Also i have tried
    starting the bot with the servos on and then remove the power and apperently
    it only matters what state the servos are in (on/off) when the BS2 starts
    the program, (ie if the servos are on when the BS2 starts and they are
    turned off afterward the BS2 still acts funny). I also have a 2200uF cap
    across the servo's power supply, which is different from the BS2's power
    supply.
    >
    > I have no idea as to what might be causing the problem. I was thinking of
    adding an optoisolator to the servo input but haven't got around to it yet.
  • ArchiverArchiver Posts: 46,084
    edited 2001-04-24 21:02
    Thanks for the suggestion, and i have a 10K resistor between the servo input and
    ground, and the 7805 i'm using to regulate voltage has problems cranking out the
    amount of milliamps needed. and how should i drive the LEDs? i have had problems
    using the 555 because it really couldn't hold the 39khz (as in it constantly
    shifted frequency) i was thinking of using a seperate prcessor for the LEDs or a
    dedicated IR detector kit.

    What i dont understand is that the program works flawlessly if the servos are
    off (but the signal is still being sent) but when i turn them on the problem
    shows up, and why it doesn't matter what I do after the initialize part of the
    program.

    thanks for you response
    Seth
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