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dual PWM on a BS2p24 — Parallax Forums

dual PWM on a BS2p24

ArchiverArchiver Posts: 46,084
edited 2002-12-09 13:36 in General Discussion
I can get a PWM to work for one motor through a SN754410 H-Bridge
(wired for dual full H-Bridge). it seems to work but I need to get 2
PWM out of this chip. I've tried very simple code. little more than
just trying to run 2 PWM commands through 2 different pinouts. If
that happens then the signal out is all on for both pins. I feel that
I don't understand the actual function by which this chip creates PWM
signals and that I'm either barking up the wrong chip or I'm just
using it incorrectly. Hopefully I'm coding it wrong otherwise I think
I'll just return the damn thing and use an HC11 despite programming
in assembly. I mean having the direction bits set for 2 motors
through the bridge works fine. How do I send 2 seperate PWM signals
out of the BS2p24? Any help would be greatly appreciated.

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2002-12-08 16:26
    You need to look at Al Williams PAK chips! He has just what you are looking
    for. The site is listed on the Parrallax web site as AWC Electronics.


    [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2002-12-09 13:36
    Can't get there with a Stamp alone.
    Also see my mesage #26716.
    More on this beastie: Not a true PWM generator like Al's PAK's. One
    channel, just a little 8 pin device. It reads a servo pulse from a
    radio rx (~1-2 ms) and puts out:
    - hi/lo signal to control a direction relay;
    - a single pulse, from short to ~20 ms, to control the FET for speed.
    Since Rx pulses are ~20 ms apart, this gives approx 0-100% duty cycle
    on the FET.
    But can be interfaced with a Stamp if customization is desired.
    Requires you to read Rx pulse, do some processing, and send out your
    own (modified) pulse, all before the next Rx pulse comes along.
    In my case, I'll read 2 Rx channels, and control 3 ESC's/motors
    independently depending on XY stick position.
    PM


    > I can get a PWM to work for one motor through a SN754410 H-Bridge
    > (wired for dual full H-Bridge). it seems to work but I need to get
    2
    > PWM out of this chip. I've tried very simple code. little more than
    > just trying to run 2 PWM commands through 2 different pinouts. If
    > that happens then the signal out is all on for both pins. I feel
    that
    > I don't understand the actual function by which this chip creates
    PWM
    > signals and that I'm either barking up the wrong chip or I'm just
    > using it incorrectly. Hopefully I'm coding it wrong otherwise I
    think
    > I'll just return the damn thing and use an HC11 despite programming
    > in assembly. I mean having the direction bits set for 2 motors
    > through the bridge works fine. How do I send 2 seperate PWM signals
    > out of the BS2p24? Any help would be greatly appreciated.
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