Stage 2 of 10 · 7 lessons · ~4 weeks

Electronics you need

Learn enough circuit theory to wire parts safely: Ohm's law, resistors for LEDs, voltage dividers, logic levels, pull-ups, a shared ground and clean power.

Start: Ohm's law and power

Lessons· one lesson for each topic, in this order

Do this

Buy or borrow a multimeter, a breadboard, jumper wires, LEDs, resistors and buttons.
Calculate an LED resistor for your board's voltage and check it with the meter.
Wire a button with a pull-up and confirm the pin levels with the meter.
Design a divider that scales a battery voltage into your input range.
Write down your board's logic level and which of your modules are 5 V.
Draw a simple schematic of your first circuit, by hand or in a free tool.

Start with

BookFree
All About Circuits Textbook
All About Circuits · Beginner
Free: read the DC volume chapters on Ohm's law, series and parallel circuits and dividers

Practise

Wokwi
Wire LEDs, resistors and buttons in a simulator first, then build the same circuit for real

Keep handy

Arduino Documentation
Board pages give each board's voltages, pin current limits and pinouts

Also worth your time

Logic Levels (opens in a new tab)Read
Why 3.3 V and 5 V parts need care, and how level shifting solves it

Before moving on: An LED with a calculated resistor and a button with a pull-up wired on a breadboard to your board, with your calculations written down and the resistor voltage measured to match within a reasonable margin.

Tauseef's advice

You do not need an electronics degree for this track, but you do need these seven ideas cold. Most of the "my code is broken" messages I get are a floating input, a missing ground or a 5 V signal on a 3.3 V pin. Buy a cheap multimeter before you buy a second board.