Building a clap-activated switch using a sound sensor and a relay, with simple 25ms timing logic that tells a clap apart from stray noise.
Understand DS3231 accuracy, temperature compensation, backup power, and the difference between the RTC IC and optional EEPROM on breakout boards.
Wiring the A4988 driver for precise stepper motor control via just the STEP and DIR pins, with a safety note on setting the current limit.
Using the L293D Motor Driver shield to control DC, stepper, and servo motors together via the AFMotor library.