Using Transistors and Driving Motors - Exploring Arduino: Tools and Techniques for Engineering Wizardry - page 74

Figure 4-6: H-bridge pin-out and logic table
Pin numbering on integrated circuits (ICs) always starts at the top-left pin
and goes around the part counter-clockwise. Chips will always have some kind
of indicator to show which pin is Pin 1, so that you don't plug the IC in upside-
down. On through-hole parts (which is what you will use exclusively in this
chapter), a half circle on one end of the chip indicates the top of the chip (where
Pin 1 is located). Some chips may have a small circle marked next to pin one on
the plastic casing in addition to, or instead of the half-circle.
Let's run through the pins and how you'll be using them:
■ GND (Pins 4, 5, 12, & 13): The four pins in the middle connect to a shared
ground between your 9V and 5V supplies.
■ V CC2 (Pin 8): V CC2 supplies the motor current, so you connect it to 9V.
■ V CC1 (Pin 16): V CC1 powers the chip's logic, so you connect it to 5V.
■ 1Y and 2Y (Pins 3 and 6): These are the outputs from the left driver. The
motor wires connect to these pins.
■ 1A and 2A (Pins 2 and 7): The states of the switches on the left are con-
trolled by these pins, so they are connected to I/O pins on the Arduino
for toggling.
■ 1,2EN (Pin 1): This pin is used to enable or disable the left driver. It is
connected to a PWM pin on the Arduino, so that speed can be controlled
dynamically.
■ 3Y and 4Y (Pins 11 and 14): These are the outputs from the right driver.
Because you are using the left driver only, you can leave these disconnected.
■ 3A and 4A (Pins 10 and 15): The states of the switches on the right are
controlled by these pins, but you are using only the left driver in this
example, so you can leave them disconnected.