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Motor Control with Raspberry Pi Pico

Overview of motors.py

The motors.py script provides a basic interface for controlling a DC motor using the Raspberry Pi Pico microcontroller. This script utilizes the MicroPython framework to access and control the Pico's hardware capabilities.

How It Works

The script controls a motor through two GPIO pins:

  1. Phase Pin (GPIO 14): Controls the motor's direction of rotation
  2. When set to 0: Motor rotates in one direction

  3. When set to 1: Motor rotates in the opposite direction

  4. Enable Pin (GPIO 15): Controls the motor's speed using Pulse Width Modulation (PWM)

  5. PWM generates a signal that rapidly switches on and off
  6. The duty cycle (percentage of "on" time) determines the average voltage delivered to the motor
  7. Higher duty cycle values result in higher motor speeds

Hardware Connection

This code is designed for use with an H-bridge motor driver or similar motor control circuit that accepts: - A direction control signal (connected to GPIO 14) - A speed control PWM signal (connected to GPIO 15)

Code Explanation

from machine import Pin, PWM
import time

# Define GPIO pins for motor control
motor_phase_pin = 14  # Direction control
motor_enable_pin = 15 # Speed control

# Initialize GPIO pins
motor_phase = Pin(motor_phase_pin, Pin.OUT)     # Digital output for direction
motor_enable = PWM(Pin(motor_enable_pin))       # PWM output for speed control

# Set initial values
motor_phase.value(0)                            # Set initial direction
motor_enable.duty_u16(int(.5*65535))            # Set speed to 50% (value range: 0-65535)

Running on the Raspberry Pi Pico

To use this code on your Raspberry Pi Pico:

  1. Connect the Pico to your computer via USB
  2. Copy the motors.py file to the Pico using Thonny IDE or another MicroPython tool
  3. The code will run automatically when the Pico powers up (if saved as main.py)
  4. Alternatively, import it in your own script: import motors

Adjusting Motor Speed

The motor speed can be adjusted by changing the PWM duty cycle value:

# Example: Change speed to 75%
motor_enable.duty_u16(int(0.75 * 65535))

# Example: Change speed to 25%
motor_enable.duty_u16(int(0.25 * 65535))

# Example: Full speed
motor_enable.duty_u16(65535)

# Example: Stop motor
motor_enable.duty_u16(0)

Changing Direction

To change the motor's direction, toggle the phase pin:

# Reverse direction
motor_phase.value(1)

# Return to original direction
motor_phase.value(0)