17-07-2012, 01:22 PM
L293D Motor Driver
Motor Driver.pdf (Size: 1.69 MB / Downloads: 23)
Introduction
One of the first realizations in robotics is that making
something move isn’t an easy task. You simply can’t take a
“brain” circuit and connect it to amotor and expect anything to
happen. The motor will simply say “HAH!” at the puny output
signal from the brains, and stay stationary. What the brain
needs is an enforcer.Muscle. Something to convince the motor
to do things the way the brains want it to be done.
There are many ways to strengthen (”buffer”) a signal so it’s
strong enough to drive a large load like a motor. Transistor Hbridges
circuit, buffer chips, and dedicated motor driving chips
are all suitable candidates, with their own benefits and
limitations.
Construction
Installing the IC
The L293D is a 16-pin chip
with a little notch cut out of
the front of it (that last bit is
for you non-experts). Orient
the chip so its notch
matches the notch in the
shape of the chip on the
PCB. Carefully drop the chip
into the gold-plated (pretty
uptown, eh?) pads, and
solder it into place from the
other side.
Construction
LED Installation
This is one of the really cool things about the ‘secret’ driver board - the
LED indicators. You have the option to mount them upside-UP or
upside-DOWN. We recommend upside-DOWN, so you can easily see
them from either side.
The tiny LEDs in your kit have a lense that can be poked into the hole of
the PCB which can easily been seen if you use the driver board on a
breadboard, or in a transparent servo case (like the Solarbotics GM4
motor). Don’t worry - you’ll still see the LED light up from the other
side too!
Usage
So you want to know how to use it? It ain’t too difficult. Here’s the
long and short of it:
Red - Vcc (‘+’)
Blue - Gnd (’-’) (on the opposite side of the cable)
Orange & Green - D1 & D2 (direction power flow of motor outputs)
Yellow - Enable (turns the chip off - connect to gnd to turn it off).
Connect the red (’+’) and blue (’-’) to power. Leave the yellow line
alone, unless if you want to turn the chip off, or pulse it to slow the
motor down (a technique called “Pulse Width Modulation). Connect
D1 to 5V, D2 to gnd, and the motor will turn one way. Connect D1
to gnd, and D2 to 5V, and the motor turns the way. Connect
D1 D2 to either 5V or gnd, and the motor is in “brake” mode
(try turning it - hard to do, eh?).
Servo Rotation Fix
If you’re planning to use the ‘secret’ motor driver in a standard servo,
you will most likely have to perform a servo hack.
Here, we’re modifying the very common Futaba S3003 / Tower Hobbies
TS-53. servos can be similarly modified, but there are a few that
really aren’t well suited to this modification. Search the Internet for
“servo rotationhack ” (or similar) for which work best.