Using a Motor Controller Board

Welcome to the Controller Board Lab

Monty waving welcome Individual transistors and H-bridge chips work great for learning. But when you want to build a real robot quickly, a motor controller board bundles everything into one neat package. Let's build something amazing!

What Is a Motor Controller Board?

A motor controller board is a small printed circuit that already has all the wiring built in. It connects your microcontroller to one or more motors with just a few wires — no loose transistors, no diodes, no messy breadboard circuits.

Most motor controller boards contain:

An H-bridge chip (so each motor can go forward or backward)
Screw terminals for the motor wires (so the connections stay tight)
A power input for the motor battery
Logic pins that plug into your Pico's GPIO pins

Key Idea

Monty thinking The motor battery and the Pico's USB power are separate. Motors need their own power supply — usually 4 × AA batteries — so they do not steal current from your Pico.

The Maker Pi RP2040 Controller Board

One popular choice for MicroPython robots is the Maker Pi RP2040 from Cytron. It has a Raspberry Pi RP2040 chip built right in, along with:

Two DC motor ports (M1 and M2) with screw terminals
Four servo ports labelled SERVO1–SERVO4
Two Grove connectors for plug-and-play sensors
A piezo buzzer and two programmable RGB LEDs

Because the RP2040 chip is already on the board, you do not need a separate Pico. You just plug in batteries, connect motors, and start coding.

Wiring a Two-Motor Robot

Follow these steps to connect two hobby DC motors to the M1 and M2 ports:

Loosen the two screws on the M1 terminal.
Insert the two wires from your left motor into M1 (one wire per hole).
Tighten the screws firmly so the wires do not pull out.
Repeat for the right motor on the M2 terminal.
Connect your 4 × AA battery pack to the VIN and GND screw terminals.
Plug the USB cable into the board to power the RP2040 logic.

Watch Out!

Monty warning Make sure the battery pack positive (red) wire goes to VIN and the negative (black) wire goes to GND. Reversing them can damage the board.

Controlling the Motors in MicroPython

The Maker Pi RP2040 motor driver uses four GPIO pins — two per motor — to set direction and speed.

Pin	Motor	Function
GP8	M1	Direction A
GP9	M1	Speed (PWM)
GP10	M2	Direction A
GP11	M2	Speed (PWM)

Here is a simple program that drives both motors forward for two seconds, then stops:

from machine import Pin, PWM
import time

# Set up Motor 1 (left motor)
m1a = Pin(8, Pin.OUT)   # direction pin
m1b = PWM(Pin(9))       # speed pin — uses PWM
m1b.freq(1000)          # 1 kHz PWM frequency

# Set up Motor 2 (right motor)
m2a = Pin(10, Pin.OUT)  # direction pin
m2b = PWM(Pin(11))      # speed pin — uses PWM
m2b.freq(1000)

def drive_forward(speed):
    """Drive both motors forward at the given speed (0–65535)."""
    m1a.value(1)         # motor 1 forward direction
    m1b.duty_u16(speed)  # motor 1 speed
    m2a.value(1)         # motor 2 forward direction
    m2b.duty_u16(speed)  # motor 2 speed

def stop():
    """Stop both motors."""
    m1b.duty_u16(0)
    m2b.duty_u16(0)

# Drive forward at 75% speed for 2 seconds, then stop
drive_forward(49152)  # 49152 is about 75% of 65535
time.sleep(2)
stop()

What Each Line Does

Line	Purpose
`PWM(Pin(9))`	Creates a PWM signal on the speed pin
`m1b.freq(1000)`	Sets the PWM frequency to 1 000 Hz
`m1a.value(1)`	Sets the direction pin HIGH (forward)
`m1b.duty_u16(49152)`	Sets speed to 75% (49 152 out of 65 535)
`m1b.duty_u16(0)`	Sets speed to 0% — motor stops

Monty's Tip

Monty giving a tip Try changing 49152 to smaller numbers like 32768 (50%) or 16384 (25%) to see how speed changes. PWM speed values range from 0 (stopped) to 65535 (full speed).

Reversing a Motor

To reverse a motor, flip the direction pin from 1 to 0:

def drive_backward(speed):
    """Drive both motors backward at the given speed (0–65535)."""
    m1a.value(0)         # direction LOW means reverse
    m1b.duty_u16(speed)
    m2a.value(0)
    m2b.duty_u16(speed)

Great Work!

Monty celebrating You can now control two motors with a real controller board — forward, backward, and stopped. Next you will combine this with sensors so your robot can detect obstacles and steer itself!