Beginner Robot Car Tutorial (Raspberry Pi 4 / Pi 5)

What you will build

A small 2WD or 4WD robot car powered by Raspberry Pi 4 or Raspberry Pi 5. It can drive forward/backward, turn left/right, and it will stop/turn when it detects an obstacle using an HC-SR04 ultrasonic sensor.

Parts list (with shopping links)

These are examples from common reputable stores. You can swap brands - just match the part type.

Build steps (detailed)

Step 1 - Assemble the chassis

1. Mount motors to the chassis.
2. Press/attach wheels firmly.
3. Install caster wheel (if included).
4. Mount the battery holder.
5. Mount the Raspberry Pi on standoffs (do not let it touch metal).

Step 2 - Wiring the motor driver

Suggested GPIO mapping (BCM): IN1=17, IN2=18, IN3=22, IN4=23. Always connect GND between Pi and driver.

Printable wiring + pin map

Print this page section for a clear pin-by-pin build reference.

Tip: the PDF is easiest to print; the PNG is best for zooming on a phone/tablet.

Step 3 - Wiring the ultrasonic sensor safely

TRIG=GPIO 24. ECHO=GPIO 25 through a resistor divider (example: 2k from Echo to GPIO, 1k from GPIO to GND).

Step 4 - Install Raspberry Pi OS

1. Flash Raspberry Pi OS (64-bit) with Raspberry Pi Imager.
2. Boot, finish setup, connect network.
3. Update: sudo apt update && sudo apt full-upgrade -y

Code

Motor test (robot_test.py)

import RPi.GPIO as GPIO
import time

GPIO.setmode(GPIO.BCM)

IN1, IN2, IN3, IN4 = 17, 18, 22, 23

for p in (IN1, IN2, IN3, IN4):
    GPIO.setup(p, GPIO.OUT)

def stop():
    for p in (IN1, IN2, IN3, IN4):
        GPIO.output(p, 0)

def forward():
    GPIO.output(IN1, 1); GPIO.output(IN2, 0)
    GPIO.output(IN3, 1); GPIO.output(IN4, 0)

try:
    forward()
    time.sleep(2)
    stop()
    time.sleep(1)
finally:
    stop()
    GPIO.cleanup()

Run: python3 robot_test.py

Obstacle avoidance (concept)

Loop: measure distance. If under 20cm - stop, turn, continue. Otherwise drive forward.

Videos that help (embedded)

These are external YouTube videos. If one ever disappears, the text tutorial still works.

Printable PDF

Download the printable version here: wolfieweb_pi_robot_tutorial.pdf