Source: https://mokxi.com/learn/arduino-debugging-practice Updated: 2026-11-11 Coding track Debugging practice # Arduino debugging practice with real planted bugs Short puzzles with one fault each, in the wiring or the code. Then the meter, scope and Serial habits that find bugs from evidence. Free In your browser 3 courses, 27 lessons, about 13 hours Start free The board with no ground See the course Overview ## How you will learn it Debugging is a skill you get by doing it, and most beginners only meet bugs by accident. Fix the bug hands you the most common ones on purpose: a missing ground, a wrong pin, a stray semicolon, an off-by-one count. Each puzzle is a few minutes. When they feel easy, Debug like an engineer adds the tools and C++ on a board shows how to find a bug from the evidence instead of guessing. Outcomes ## What you will learn - Spot the wiring faults that keep a circuit dark. - Find the code faults that make a sketch almost work. - Use Serial output as evidence, not decoration. - Work through a circuit with several bugs in a fixed order. Your route ## The courses and lessons to take Every lesson opens in the editor right away, signed in or not, and the simulator checks each step. - Step 1 · 8 lessons · 1 h ### Fix the bug Short puzzles, a few minutes each. - The board with no ground Pin 13 is high, the LED and resistor are wired to the rail, and nothing lights. Find what the loop is missing. - The output that is not an output digitalWrite says HIGH and the LED barely glows. The loop is fine. Find what setup() leaves out. - The count that stops at nine A for loop that should print 1 to 10 prints 1 to 9 and says done. Find where ten went. - The if that always runs The LED should light only while the button is held, and it is on all the time. One character is to blame. Every lesson in the course - Step 2 · 13 lessons · 10 h ### C++ on a board A bug found from the evidence. - A bug, found from the evidence A score that goes down on the fifth press and a lamp that goes out when it should stay on. Find it from what the board prints, not from staring at the code. Every lesson in the course - Step 3 · 6 lessons · 2 h ### Debug like an engineer Serial like a pro, then one circuit with three bugs. - Reading Serial like a pro Print debugging done well: labeled and timestamped lines, a warning word you can search for, and a verbose switch you flip from the Serial Monitor without rebuilding. - Boss: one circuit, three bugs A button and an LED that do nothing, with three faults planted at once. Use the method engineers use (reproduce, isolate, measure, fix) and a meter to find all three. Every lesson in the course Keep going ## Guides and tools on the same subject Guide ### How to debug Arduino code Open it Guide ### Arduino compile errors explained Open it Tool ### Fix a broken circuit or sketch Open it Track ### Coding track Python and C++ from your first print to classes, tests and state machines. Every program runs on a simulated board, so a bug is something you can see. See the whole track Questions ## Questions people ask What are the most common Arduino bugs? A missing ground, a pin never set to OUTPUT, a button read without a pull-up, a loop that stops one short, and an if with a stray semicolon. Fix the bug has each of them. How do I debug an Arduino without a debugger? Print what the code believes with Serial, measure what the circuit is doing with a meter or scope, and compare the two. The lessons build that habit. Is this good practice for interviews? Yes. Explaining how you found a bug, step by step, is exactly what hardware and firmware interviews ask for.