Re: looking for THE dc drive motor speed controller solution

On Thu, 3 Aug 2006 01:53:57 -0400, "pogo" <pogo@xxxxxxxxxxxxx>
wrote:

Well I am frustrated. I thought had "THE" solution for driving my
DC drive gear motors, but it appears that PWM from one device is
not the same as PWM from another. crap! ( or --- I am not asking
the right questions / lack of understanding, etc ... ) I thought I
had the perfect H-bridge device that I could control from either a
Acroname Moto 1.0 module or Servo Controller module until I
discovered (if I am interpreting the technical advice correctly)
that I can't get the speed control granularity I want that way ---
it sounds like I can only get near full speed that way.

Here are my specs:

The brains of the robot will be a mini-PC board (ITA, etc.)
It will need to control a servo controller (like Parallax,
Lynxmotion, etc. for arms/grippers/camera pan/tilt)
It will need to control 2 reversable DC gear motors for
differential drive and steering

I want as few external boards as possible, for power consumption,
weight, etc. In other words, if I could get the servo controller to
also send signals to the motor speed controller that would great!

Motor controller must be affordable (between $25 to $80 to control
2 motors; $100 MAX !!! )

connects to mini-PC board via serial port or USB
gets commands from PC to set speed & direction & stopping
OR
will receive PWM signals from a PC-based servo controller
one channel will connect to one 6-12VDC gear motor, reversable

Entire system will run on 12VDC, max. I *could* go to 24VDC if need
be, but I really don't want to for obvious reasons.

Any suggestions ?
Thanks !
JCD

You might get a servo control chip and a PWM chip from below and
put them on a single small board. The bottom link shows how
simple a servo control setup can be. For the PWM control of
motors you would probably need some high current MOFET
transistors in an H-bridge to rapidly turn on/off the current to
the motor.

http://www.kronosrobotics.com/xcart/customer/home.php?cat=292
http://www.geocities.com/zoomkat/ezservo.htm
.

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