A typical H-bridge has two inputs, two outputs, and two voltage supplies. The voltage supplies are called logic supply, typically about 5 volts at a few milliamps, and motor supply which can be any amount of voltage and amperage that your motor needs. This particular H-bridge needs a 5-volt logic supply, and a 5-to-30-volt motor supply. The motor supply can control up to 1 amp. If you send a small amount of voltage into the input (whatever the logic supply voltage is), it will allow voltage to flow from the H-bridge's motor supply to the corresponding output. Likewise, if you take the input pin to ground, the output goes low.
The L293D is a "Standard Quadruple Half-H Driver" which means that it's got two H-bridges in it. It's functionally the same as the SNXXXX chip, another quadruple half-H driver.
Stepper motors can be used to create projects that require fine motor control. A bi-polar stepper has two coils that have to have their polarity reversed in a set sequence in order for the motor to move. H-bridges are perfect for this task.
To control the inputs of an H-bridge, you need a microcontroller. You'll find sample code here for the PIC micrcontroller in PicBasic Pro, and the [# Arduino] and [# Wiring] microcontroller modules. If you don't like those, you can use any other microcontroller you prefer.
Please let us know what you've done!
Step 1: Get some stuff...
This one is pretty simple, mostly just get yourself some wire and two capacitors but here is the list.
1. Black Wire (22AWG, solid)
2. Red Wire (22AWG, solid)
3. Green Wire (22AWG, solid)
4. Blue Wire (22AWG, solid)
5. Yellow Wire (22AWG, solid)
6. 1 10 uF Capacitor (Electrolytic Radial Lead)
7. 1 1uF Capacitor (Electrolytic Radial Lead)
8. 1 Small Solderless Breadboard ( we're using one 3.25"x2.125", 400pnt )
9. Line of 4 male headers
10. Line of 4 female headers
11. 2 sets of 2 female headers
Honestly, you can do it all in chartreuse if you can find it, but the colors we are using are pretty standard.
Red = Power
Black = Ground
Blue/Red/Yellow/Black = stepper control lines
There is some green wire that we are going to use to hold the enable pins to logic power (more on that later). Some times those pins might go to something else other than just clean straight power, so we decided to differentiate them a bit.