DC motor control in Python

In this section, we will discuss motor control using the Raspberry Pi Zero. Why discuss motor control? As we progress through different topics in this book, we will culminate in building a mobile robot. Hence, we need to discuss writing code in Python to control a motor using a Raspberry Pi.

In order to control a motor, we need an H-bridge motor driver (Discussing H-bridge is beyond our scope. There are several resources for H-bridge motor drivers: http://www.mcmanis.com/chuck/robotics/tutorial/h-bridge/). There are several motor driver kits designed for the Raspberry Pi. In this section, we will make use of the following kit: https://www.pololu.com/product/2753.

The Pololu product page also provides instructions on how to connect the motor. Let's get to writing some Python code to operate the motor:

from gpiozero import Motor 
from gpiozero import OutputDevice 
import time

motor_1_direction = OutputDevice(13) 
motor_2_direction = OutputDevice(12)

motor = Motor(5, 6)

motor_1_direction.on() 
motor_2_direction.on()

motor.forward()

time.sleep(10)

motor.stop()

motor_1_direction.off() 
motor_2_direction.off()

Raspberry Pi based motor control

In order to control the motor, let's declare the pins, the motor's speed pins and direction pins. As per the motor driver's documentation, the motors are controlled by GPIO pins 12, 13 and 5, 6, respectively.

from gpiozero import Motor 
from gpiozero import OutputDevice 
import time 

motor_1_direction = OutputDevice(13) 
motor_2_direction = OutputDevice(12) 

motor = Motor(5, 6)

Controlling the motor is as simple as turning on the motor using the on() method and moving the motor in the forward direction using the forward() method:

motor.forward()

Similarly, reversing the motor direction could be done by calling the reverse() method. Stopping the motor could be done by:

motor.stop()