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URGENT HELP REQUESTED (Part-I) !!! — Parallax Forums

URGENT HELP REQUESTED (Part-I) !!!

ArchiverArchiver Posts: 46,084
edited 2003-07-01 17:27 in General Discussion
Hello buddies,

I am very badly in need of help and would really appreciate
assistance from anybody & everybody.

My project consists of two parts, and presently, I seek help up with
the first portion.

I am using an analog joystick to drive two DC motors to achieve
motion in the desired direction (Forward/Backward/Left/Right). In
between, I have an LTC1298 to convert my input from the joystick and
send it to the BS2 (REV F), from where I am using a Motor Mind C to
drive the motors.

Earlier, I had the complete set-up tested without using the joystick,
but, sending in fixed pulses to the MMC (similar to the Canonbot),
and everything worked fine.

But, now after incorporating the joystick, nothing seems to work. I
am in serious trouble and need help from you folks. Can you suggest
what might have gone wrong and remedies, if any? I'll be glad to
provide more details if required.

I'll discuss about the second portion after fixing this one.

Thank you in advance.
Sashi.

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2003-06-30 16:54
    Ever think about connecting the joystick straight to the MotorMind C.
    One of the features is an analog input.


    > I am very badly in need of help and would really appreciate
    > assistance from anybody & everybody.
    >
    > My project consists of two parts, and presently, I seek help up with
    > the first portion.
    >
    > I am using an analog joystick to drive two DC motors to achieve
    > motion in the desired direction (Forward/Backward/Left/Right). In
    > between, I have an LTC1298 to convert my input from the joystick and
    > send it to the BS2 (REV F), from where I am using a Motor Mind C to
    > drive the motors.
  • ArchiverArchiver Posts: 46,084
    edited 2003-06-30 17:05
    At 03:51 PM 6/30/03 +0000, sashikumarkonda wrote:
    >Hello buddies,
    >
    >I am very badly in need of help and would really appreciate
    >assistance from anybody & everybody.
    >
    >My project consists of two parts, and presently, I seek help up with
    >the first portion.
    >
    >I am using an analog joystick to drive two DC motors to achieve
    >motion in the desired direction (Forward/Backward/Left/Right). In
    >between, I have an LTC1298 to convert my input from the joystick and
    >send it to the BS2 (REV F), from where I am using a Motor Mind C to
    >drive the motors.
    >
    >Earlier, I had the complete set-up tested without using the joystick,
    >but, sending in fixed pulses to the MMC (similar to the Canonbot),
    >and everything worked fine.
    >
    >But, now after incorporating the joystick, nothing seems to work. I
    >am in serious trouble and need help from you folks. Can you suggest
    >what might have gone wrong and remedies, if any? I'll be glad to
    >provide more details if required.
    >
    >I'll discuss about the second portion after fixing this one.
    >
    >Thank you in advance.
    >Sashi.

    Hi Sashi -

    You don't mention if you obtained the LTC1298 from Parallax, but if you
    didn't you may want to look a the documentation for the AppMod they offer
    for that
    chip. The documentation can be found here:
    <http://www.parallax.com/html_pages/downloads/bsaccessories/documentation_access\
    ories.asp

    > (copy and paste, if necessary, into your browser).

    Check both the wiring of the chip, and the programming, as shown in the docs.

    Other than that, a snippet of the actual code you're using to access the
    LTC1298 might be helpful.

    Regards,

    Bruce Bates
  • ArchiverArchiver Posts: 46,084
    edited 2003-06-30 17:06
    What values are you reading from the joystick?
    What kind of joystick is it?
    How many analog channels are you reading?

    Have you written a program on the BS2 just
    to read the 1298 while moving the joystick?
    What kind of values does it produce?
    What is the 'center' value of the joystick?
    (typically 0 is all the way one side, while
    +5 is all the way the other)

    Are you providing both GND and +5 to the
    joystick?

    --- In basicstamps@yahoogroups.com, "sashikumarkonda"
    <sashikumarkonda@y...> wrote:
    > Hello buddies,
    >
    > I am very badly in need of help and would really appreciate
    > assistance from anybody & everybody.
    >
    > My project consists of two parts, and presently, I seek help up
    with
    > the first portion.
    >
    > I am using an analog joystick to drive two DC motors to achieve
    > motion in the desired direction (Forward/Backward/Left/Right). In
    > between, I have an LTC1298 to convert my input from the joystick
    and
    > send it to the BS2 (REV F), from where I am using a Motor Mind C to
    > drive the motors.
    >
    > Earlier, I had the complete set-up tested without using the
    joystick,
    > but, sending in fixed pulses to the MMC (similar to the Canonbot),
    > and everything worked fine.
    >
    > But, now after incorporating the joystick, nothing seems to work. I
    > am in serious trouble and need help from you folks. Can you suggest
    > what might have gone wrong and remedies, if any? I'll be glad to
    > provide more details if required.
    >
    > I'll discuss about the second portion after fixing this one.
    >
    > Thank you in advance.
    > Sashi.
  • ArchiverArchiver Posts: 46,084
    edited 2003-07-01 17:27
    Hi,

    Thanks for the fast response. I have not solved my problem yet, but,
    this is in reply to your queries:

    Bill - about connecting the joystick straight to the MMC, I have
    another task in mind for the joystick, hence, I cannot do that.

    Alan - I am basically trying to read in the voltages from the
    joystick and use these in turn to drive my motors. It is an analog
    joystick having two channels. I do have a program, very much similar
    to the one for LTC1298. The center value of the joystick is 2V,
    Forward: 1.6V & Backward: 2.4V as obtained from one channel & Left:
    2.3V & Right: 1.9V as obtained from the other channel. In the Debug
    window, the values produced correspond to these voltages i.e.

    for center position:
    channel0: 2043
    channel1: 2045

    forward:
    channel0: 2026
    channel1: 1651

    backward:
    channel0: 2013
    channel1: 2346

    left:
    channel0: 2303
    channel1: 2025

    right:
    channel0: 1908
    channel1: 2014

    Yes, I am providing both GND & +5V to the joystick.

    Bruce - I have actually used the document as a reference for my
    circuit and the program, so, everything is pretty much the same.

    I feel there is something to do with a communication problem between
    the BS2 & the MMC. Can anyone help me in this regard?

    I have another question, might sound silly though. In the LTC
    program, the input toggles between 0 & 1 (oddSign = 0 to 1 , where
    oddSign is a VAR) to give out channel0 & channel1 respectively on the
    Debug screen. Is there anyway I can assign (oddSign = 0) to a VAR say
    CH0 & (oddSign = 1) to another VAR say CH1 so that my algorithm would
    be something like this:

    If CH0>2000 & CH1<1700 THEN PWM_REG1 = & PWM_REG2 = ( the PWM values
    correspond to forward motion of the motors)

    and so on and so forth for the other directions.

    or

    can I directly use:

    If (oddSign = 0)>2000 & (oddSign = 1)<1700 THEN PWM_REG1 = & PWM_REG2
    =

    Hope this gives you an idea as to where my problem might be.

    Thank you all once again in advance.

    Sashi.

    > At 03:51 PM 6/30/03 +0000, sashikumarkonda wrote:
    > >Hello buddies,
    > >
    > >I am very badly in need of help and would really appreciate
    > >assistance from anybody & everybody.
    > >
    > >My project consists of two parts, and presently, I seek help up
    with
    > >the first portion.
    > >
    > >I am using an analog joystick to drive two DC motors to achieve
    > >motion in the desired direction (Forward/Backward/Left/Right). In
    > >between, I have an LTC1298 to convert my input from the joystick
    and
    > >send it to the BS2 (REV F), from where I am using a Motor Mind C to
    > >drive the motors.
    > >
    > >Earlier, I had the complete set-up tested without using the
    joystick,
    > >but, sending in fixed pulses to the MMC (similar to the Canonbot),
    > >and everything worked fine.
    > >
    > >But, now after incorporating the joystick, nothing seems to work. I
    > >am in serious trouble and need help from you folks. Can you suggest
    > >what might have gone wrong and remedies, if any? I'll be glad to
    > >provide more details if required.
    > >
    > >I'll discuss about the second portion after fixing this one.
    > >
    > >Thank you in advance.
    > >Sashi.
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