Raspberry Pi Robot Car: Motors, Chassis, Control

Parts List

• Pi (any model with GPIO — a Zero 2 W keeps weight down)
• 2WD or 4WD robot chassis kit (cheap, widely available)
• L298N or TB6612FNG motor driver — L298N is easier to find, TB6612 is more efficient (less voltage drop, runs cooler)
• Separate battery pack for motors (2x 18650 or a dedicated motor battery) — never power motors off the Pi's 5V rail directly, the back-EMF and current draw will brown out or damage the Pi
• USB power bank or dedicated 5V regulator for the Pi itself

Wiring the L298N

• Motor driver's logic inputs (IN1-IN4) → any 4 free GPIO pins
• ENA/ENB (enable/speed control) → 2 PWM-capable GPIO pins
• Motor driver's 12V/VCC input → motor battery pack (not the Pi)
• Motor driver GND → shared common ground with the Pi's GND (critical — without a common ground reference, PWM signals won't read correctly)
• Motor outputs (OUT1-OUT4) → the two DC motors

Basic Control Code (gpiozero)

from gpiozero import Motor left = Motor(forward=17, backward=27, enable=18) right = Motor(forward=22, backward=23, enable=24) def forward(speed=0.6): left.forward(speed) right.forward(speed) def turn_left(speed=0.5): left.backward(speed) right.forward(speed) forward()

gpiozero's Motor class handles the PWM enable pin and direction pins together — much less boilerplate than raw RPi.GPIO.

Adding Remote Control

Simplest path: a small Flask web server on the Pi serving a page with directional buttons that hit endpoints calling the motor functions — control it from any phone on the same WiFi network, no app needed. For lower latency, a gamepad over Bluetooth paired to the Pi with evdev reading joystick input works well too.

Adding Obstacle Avoidance

An HC-SR04 ultrasonic sensor (trigger/echo pins, 5V, cheap) mounted facing forward, polled in a loop — if distance drops below a threshold, stop and turn. This pairs naturally with the line-follower/obstacle-avoidance robot guide if you want to go further with sensor fusion.

Common Mistakes

• Forgetting the common ground between motor battery circuit and Pi circuit — causes erratic/no motor response even though wiring "looks right."
• Undersized motor battery — cheap 2xAA packs sag hard under stall current when the robot hits an obstacle, browning out the driver board.