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Help. Using Basic Stamps with the Dual Motor Driver MC33926 ( Parallax code 28820) — Parallax Forums

Help. Using Basic Stamps with the Dual Motor Driver MC33926 ( Parallax code 28820)

markustermarkuster Posts: 184
edited 2013-07-10 11:47 in BASIC Stamp
Hi,

It is very difficult to understand how can I use the Dual Motor Driver MC33926 ( Parallax code 28820)
with a Basic Stamp.

Do you have a little connection diagram or something like that
and
Do you have a simple B.Stamp code in PBasic to use the Basic Stamp with this Motor Driver ?


Link of the Parallax product:
http://www.parallax.com/StoreSearchResults/tabid/768/txtSearch/MC33926/List/0/SortField/4/ProductID/786/Default.aspx



Please Help

Thanks.

Comments

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2013-06-27 11:32
    Since that device is an H-Bridge / Motor Driver and not a motor controller everything is driven (logic) by the MCU. This means typically more I/O lines consumed in order to handle all the functions. For speed control you must manually drive the inputs with PWM, which works for the Propeller Chip, however the BASIC Stamp would not have speed control using this driver. Your motors would be fully on or off. You would use only HIGH/LOW commands to turn a given motor on/off and change direction.

    I also meant to add that the documentation describes the connections required, but you can ignore PWM for the BASIC Stamp. You will simply make an I/O line HIGH/LOW on one the two motor inputs to make the motor go in a given direction, reverse the states for the opposite direction and both low to stop. Again, remember that on the BASIC Stamp you won't have speed control. Just full on/off.
  • markustermarkuster Posts: 184
    edited 2013-06-28 08:15
    Very Clear Chris:

    And what abut an other commnad like PULSOUT from the Basic Stamp (instead PWM) .

    I am asking you now about PULSOUT because it is very easy to move a servo in any direction
    and speed with this comand and a Basic Stamp.

    Do you know if it could be work ?

    And the last question : why the Propeller will do the job ? . It is because the speed of the Propeller or
    something else?

    Thanks.
  • Mike GreenMike Green Posts: 23,101
    edited 2013-07-10 10:50
    The PWM statement is not meant to be used to drive a motor because it switches very rapidly, often too fast for the motor driver, to produce an average on-time as requested. This works for making a simple digital to analog converter, but not for driving a motor. The PULSOUT statement can provide a very accurate on-time, but the off-time is not well controlled. Sometimes people use two PULSOUTs in a tight loop with one PULSOUT setting the on-time and another "dummy" PULSOUT to an unused I/O pin to set the off-time. In any event, you can control only one motor at a time. Servos operate completely differently from a combination of a DC motor and an H-Bridge even though servos are built with a DC motor and an H-Bridge internally.

    The Propeller is fast enough to produce several accurate PWM signals at the same time, even when only one cog is used. By using multiple cogs, it can do the PWM generation in one cog while the main program continues to run (along with other stuff as well).
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2013-07-10 11:47
    Somehow I missed your reply and Mike got it for me. If you have additional questions please let me know.
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