Stage 2 · Lesson 6 of 7
Common ground and clean power
Voltages are always measured relative to ground, so every connected part must share one: join the ground of each supply, and module. A turns a battery or adapter voltage into the steady voltage your chip needs, and small near each chip, called decoupling capacitors, absorb quick dips when current jumps.
transmissions, relays and motors pull sudden bursts of current; if the supply cannot keep up, the chip browns out (its too low) and resets. Motors, servos and LED strips need their own supply with grounds joined.
Common trappowering a motor or servo from the board's 3.3 V or 5 V pin, which produces random resets that look exactly like a crashing program.
A question to check yourself, an AI practice session and 2 cheat sheet entries come with the full roadmap. Unlock
Resources for this stage
Start with
- BookFreeAll About Circuits Textbook
All About Circuits · Beginner
Free: read the DC volume chapters on Ohm's law, series and parallel circuits and dividers
Practise
Keep handy
Also worth your time
Why 3.3 V and 5 V parts need care, and how level shifting solves it