Arduino & IoT Fundamentals

Motors, Displays and Power

35 min

Motors need drivers

Microcontroller pins provide only a few milliamps. Motors need far more current, and they create voltage spikes.

Motor Driver
Small servo powered from a suitable supply; signal from a pin (Servo library)
DC motor motor driver board (e.g. TB6612 or DRV8833) or a MOSFET with a flyback diode
Stepper motor stepper driver (A4988, TMC2209)
Relay (switching other circuits) relay module with driver and isolation

Use a separate power supply for motors, sharing ground with the microcontroller.

Displays

  • OLED (SSD1306, I²C): small, sharp text and graphics.
  • LCD 16×2 with I²C backpack: simple text.
  • TFT screens (SPI): colour interfaces.
  • LED strips (WS2812/"NeoPixel"): addressable colour LEDs; need adequate 5 V power and a resistor on the data line.

Power

  • USB power is fine for small projects.
  • Batteries: choose by voltage and capacity; lithium batteries need proper charging and protection circuits.
  • Deep sleep on ESP32 reduces power to microamps between readings, letting battery sensors run for months.
  • Add decoupling capacitors near power-hungry parts if things reset randomly.

Exercise

Build a plant monitor: a soil-moisture sensor and an OLED display showing the moisture level, with a small pump or LED (through a MOSFET or driver and its own supply) triggered when the soil is dry.

Check yourself

  • Why can't a motor be powered directly from a pin?
  • Why must separate supplies share ground?
  • How does deep sleep extend battery life?

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