Raspberry Pi and Pico

Learn

What you’ll learn

• The difference between a Raspberry Pi and a Raspberry Pi Pico
• When a robot needs a full computer
• How Pi and microcontroller can work together

Two very different boards

	Raspberry Pi (e.g. Pi 4 / Pi 5)	Raspberry Pi Pico
Type	Full computer running Linux	Microcontroller
Runs	Python, OpenCV, ROS 2, a desktop	One program: MicroPython or C/C++
Starts up in	Tens of seconds	Instantly
Power	5 V, several amps (the Pi 5 wants a 27 W USB-C supply)	Tiny
Good at	Cameras, AI, maps, Wi-Fi, heavy maths	Precise timing, reading sensors, driving motors
Price	~$35–80	~$4–7

Using a Pi in a robot

• Program it in Python; the gpiozero library makes pins easy.
• Add a camera for computer vision.
• It’s not real-time, so for precise motor timing many robots pair a Pi (brain) with a microcontroller (spinal cord): the Pi decides “turn left”, and a Pico or Arduino runs the motors and reads encoders.

Caution

Pi GPIO pins are 3.3 V and can’t drive motors directly. Use a motor driver, and give the Pi a proper power supply, separate from the motors’ battery (grounds joined).

Examples

Example: gpiozero on a Raspberry Pi

from gpiozero import Robot, DistanceSensor
from time import sleep

robot = Robot(left=(4, 14), right=(17, 18))     # motor driver pins
sensor = DistanceSensor(echo=24, trigger=23)    # use a divider on ECHO

while True:
    if sensor.distance < 0.2:     # metres
        robot.right(0.5)
    else:
        robot.forward(0.6)
    sleep(0.05)

Example: Pi talks to a Pico over USB serial

The Pi sends "L 120\n", the Pico reads the line and sets the left motor to 120. The Pi does the thinking; the Pico does the timing.

Practice

Try it in a virtual Raspberry Pi Pico

Press Start simulator, paste into main.py, and press ▶.

main.py

from machine import Pin
import time

led = Pin(25, Pin.OUT)
while True:
    led.toggle()
    print("tick")
    time.sleep(0.5)

Virtual Raspberry Pi Pico (MicroPython)Open full screen ↗

Start simulator

Runs on Wokwi, free, no account needed.

Pi or Pico?Easy

Which would you choose for: a robot that recognises faces; a precise stepper plotter; a battery-powered line follower? Pi (camera + AI); Pico (precise timing); Pico (simple, low power, instant start).

SOS on the PicoMedium

Blink SOS on the virtual Pico’s LED.

Brain and spinal cordHard

Design the split of jobs between a Pi and a Pico for a robot that follows a coloured ball. Pi: camera, find the ball’s position, decide the steering. Pico: read encoders, run a PID loop on wheel speeds, receive speed commands from the Pi over serial.

Quick check

1. Which is a full Linux computer?

Raspberry Pi 5Raspberry Pi PicoArduino UNOmicro:bit

2. Why pair a Pi with a microcontroller?

The microcontroller handles precise real-time jobsPis can’t run PythonTo save weightIt isn’t useful

3. Raspberry Pi GPIO pins are…

5 V3.3 V12 VMains

Check my answers