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Lesson 31: Centrifugal Pump

In this lesson, you will learn how to operate a centrifugal pump using the Raspberry Pi Pico W and an L9110 motor control board. We’ll guide you through the process of configuring two PWM (Pulse Width Modulation) pins to control the motor. You’ll set up the pump to run for 5 seconds and then turn off. This practical exercise offers a valuable opportunity to delve into motor control mechanisms and PWM signals, crucial in microcontroller programming.

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

Universal Maker Sensor Kit

94

Universal Maker Sensor Kit

You can also buy them separately from the links below.

Component Introduction

Purchase Link

Raspberry Pi Pico W

BUY

Centrifugal Pump

-

L9110 Motor Driver Module

-

Breadboard

BUY

Wiring

../_images/Lesson_31_Pump_pico_bb.png

Code

from machine import Pin, PWM
import time

pump_a = PWM(Pin(26), freq=1000)
pump_b = PWM(Pin(27), freq=1000)

# turn on pump
pump_a.duty_u16(0)
pump_b.duty_u16(65535)  # speed(0-65535)

time.sleep(5)

# turn off pump
pump_a.duty_u16(0)
pump_b.duty_u16(0)

Code Analysis

  1. Importing Libraries

    • The machine module is imported to interact with the GPIO pins and PWM functionalities of the Raspberry Pi Pico W.

    • The time module is used for creating delays in the code.


    from machine import Pin, PWM
import time

  2. Initializing PWM Objects

    • Two PWM objects, pump_a and pump_b, are created. They correspond to GPIO pins 26 and 27, respectively.

    • The frequency for PWM is set to 1000 Hz, a common frequency for motor control.


    pump_a = PWM(Pin(26), freq=1000)
pump_b = PWM(Pin(27), freq=1000)

  3. Turning on the Pump

    • pump_a.duty_u16(0) sets the duty cycle of pump_a pin to 0, while pump_b.duty_u16(65535) sets the duty cycle of pump_b pin to 65535, running the motor at full speed. For more details, please refer to the working principle of L9110.

    • The pump runs for 5 seconds, controlled by time.sleep(5).


    # turn on pump
pump_a.duty_u16(0)
pump_b.duty_u16(65535)  # speed(0-65535)
time.sleep(5)

  4. Turning off the Pump

    Both pump_a and pump_b are set to a duty cycle of 0, stopping the motor.

    # turn off pump
pump_a.duty_u16(0)
pump_b.duty_u16(0)