For our last experiment in this batch, we're controlling a servo motor, the same kind used for automotive throttle bodies, HVAC vent flaps, and mirror positioning. Unlike the plain DC motors in Experiments 18 and 19, a servo doesn't just spin, it moves to and holds a specific angle you command it to, using a precisely timed PWM signal.

2. Scope

We'll understand how a servo interprets pulse width, rather than duty cycle percentage, as a position command, set up a timer to produce the specific 50Hz signal servos expect, and sweep it smoothly from 0° to 180° and back. This extends the PWM skills from Experiments 3 and 12 to a genuinely new use, position control instead of brightness.

3. Prerequisite

3.1 Hardware

• STM32 Nucleo-F070RB development board

• Standard hobby servo motor (e.g. SG90 or similar, 5V, 3-wire)

• Breadboard and jumper wires

• Micro-USB cable

3.2 Software

• STM32CubeMX (standalone)

• STM32CubeIDE

• ST-LINK USB driver