4.1 Small Fan

In this engaging project, we’ll explore how to drive a motor using the L293D.

The L293D is a versatile integrated circuit (IC) commonly used for motor control in electronics and robotics projects. It can drive two motors in both forward and reverse directions, making it a popular choice for applications requiring precise motor control.

By the end of this captivating project, you will have gained a thorough understanding of how digital signals and PWM signals can effectively be utilized to control motors. This invaluable knowledge will prove to be a solid foundation for your future endeavors in robotics and mechatronics. Buckle up and get ready to dive into the exciting world of motor control with the L293D!

Required Components

In this project, we need the following components.

It’s definitely convenient to buy a whole kit, here’s the link:

Name	ITEMS IN THIS KIT	LINK
ESP32 Starter Kit	320+	ESP32 Starter Kit

You can also buy them separately from the links below.

COMPONENT INTRODUCTION	PURCHASE LINK
ESP32 WROOM 32E	BUY
ESP32 Camera Extension	-
Breadboard	BUY
Jumper Wires	BUY
DC Motor	BUY
L293D	-

Available Pins

Here is a list of available pins on the ESP32 board for this project.

Available Pins

IO13, IO12, IO14, IO27, IO26, IO25, IO33, IO32, IO15, IO2, IO0, IO4, IO5, IO18, IO19, IO21, IO22, IO23

Schematic

Wiring

Note

Since the motor requires a relatively high current, it is necessary to first insert the battery and then slide the switch on the expansion board to the ON position to activate the battery supply.

Code

Note

• Open the 4.1_motor_turn.py file located in the esp32-starter-kit-main\micropython\codes path, or copy and paste the code into Thonny. Then, click “Run Current Script” or press F5 to execute it.

• Make sure to select the “MicroPython (ESP32).COMxx” interpreter in the bottom right corner.

import machine
import time

# Create Pin objects representing the motor control pins and set them to output mode
motor1A = machine.Pin(13, machine.Pin.OUT)
motor2A = machine.Pin(14, machine.Pin.OUT)

# Define a function to rotate the motor clockwise
def clockwise():
    motor1A.value(1)
    motor2A.value(0)

# Define a function to rotate the motor anticlockwise
def anticlockwise():
    motor1A.value(0)
    motor2A.value(1)

# Define a function to stop the motor
def stop():
    motor1A.value(0)
    motor2A.value(0)

# Enter an infinite loop

try:
    while True:
        clockwise() # Rotate the motor clockwise
        time.sleep(1) # Pause for 1 second
        anticlockwise() # Rotate the motor anticlockwise
        time.sleep(1)
        stop() # Stop the motor
        time.sleep(2)

except KeyboardInterrupt:
    stop()  # Stop the motor when KeyboardInterrupt is caught

During script execution, you will see the motor alternately rotating clockwise and counterclockwise every second.

Learn More

In addition to simply making the motor rotate clockwise and counterclockwise, you can also control the speed of the motor’s rotation by using pulse-width modulation (PWM) on the control pin, as shown below.

Note

• Open the 4.1_motor_turn_pwm.py file located in the esp32-starter-kit-main\micropython\codes path, or copy and paste the code into Thonny. Then, click “Run Current Script” or press F5 to execute it.

• Make sure to select the “MicroPython (ESP32).COMxx” interpreter in the bottom right corner.

from machine import Pin, PWM
import time

# Create PWM objects representing the motor control pins and set their frequency to 1000 Hz
motor1A = PWM(Pin(13, Pin.OUT))
motor2A = PWM(Pin(14, Pin.OUT))
motor1A.freq(500)
motor2A.freq(500)

# Enter an infinite loop
while True:
    # Rotate the motor forward by gradually increasing the power on the motor1A pin
    for power in range(0, 1023, 20):
        motor1A.duty(power)
        motor2A.duty(0)
        time.sleep(0.1)
    # Decreasing the power on the motor1A pin
    for power in range(1023, 0, -20):
        motor1A.duty(power)
        motor2A.duty(0)
        time.sleep(0.1)
    # Rotate the motor in the opposite direction by gradually increasing the power on the motor2A pin
    for power in range(0, 1023, 20):
        motor1A.duty(0)
        motor2A.duty(power)
        time.sleep(0.1)
    # Decreasing the power on the motor2A pin
    for power in range(1023, 0, -20):
        motor1A.duty(0)
        motor2A.duty(power)
        time.sleep(0.1)

Unlike the previous script, here the motor is controlled by PWM signals with a frequency of 1000 Hz, which determines the speed of the motor.

• The code uses a while True loop to run continuously. Inside the loop, there are four for loops that control the motors in a sequence.

• The first two for loops increase and decrease the speed of IN1 while keeping IN2 at 0 speed.

• The next two for loops increase and decrease the speed of IN2 while keeping IN1 at 0 speed.

• The range function in each for loop produces a string of numbers that serves as the duty cycle of the PWM signal. This is then output to IN1 or IN2 via the duty method. The duty cycle determines the percentage of time that the PWM signal is high, which in turn determines the average voltage applied to the motor, and thus the motor speed.

• The time.sleep function is used to introduce a delay of 0.1 seconds between each step in the sequence, which allows the motor to change speed gradually, rather than jumping from one speed to another instantaneously.