Waiting for numeric Serial output.
Start with a working circuit. Run it, explore its controls, then make it your own.
Watch: Intro to CircuitXO
Open Learning Pathways for guided lessons on electronics, Arduino, and robot simulation. Choose a lesson, explore its circuit, and open the complete circuit in a separate workbench. New to circuits? Start with Make your first light.
Browse Examples to search ready-made circuits. Each example opens in a new tab so you can keep browsing. Examples open as editable working copies; your changes do not replace the published example.
Explore the component library, workbench, project controls, and robot tools one area at a time. You can return to this tour from Help whenever you need it.
Search the component library, then drag a component onto the workbench, or click it and click where you want to place it. Green seating targets show where leads will connect to breadboard holes. Outside the breadboard, move a free component pin onto another free pin to make a direct connection. Green targets confirm the connection. Moving the attached component away disconnects it. Select a component to inspect its connections and change its properties. The resistor inspector includes a resistance unit selector and a color-code reference with four-band and five-band examples.
Click a terminal or breadboard hole to start a wire. Click empty space to set its path, then click another terminal or hole to finish. Select a wire to see its endpoint and bend handles. Double-click or Ctrl-click a wire to add one bend point, then drag that point to shape it; add more points as needed.
With no wire selected, the auto-route button toggles right-angle drawing for new wires. It stays highlighted while that mode is active; click it again or press Esc to leave the mode. With a wire selected and the mode off, click auto-route to convert that wire to right-angle routing. Use Reset wire bends to clear its bends, or Connect by name to choose connections from lists.
Click Start simulation to run the circuit. Operate switches and potentiometer knobs during simulation, and select components to see available readings and controls. Click Stop simulation before moving components or changing wiring.
You can build and simulate without signing in. Open My Projects to sign in with Google and save a named cloud project. Changes to an editable saved project save automatically. Project badges indicate private access, view/remix sharing, and invited editors.
Use Share to set link access or invite editors. A personal project shared for viewing or remixing opens read-only for other users; sign in and choose Remix into My Projects to save an editable copy. Invited editors work on the shared original.
New starts a fresh circuit. Open loads a CircuitXO JSON file, Download saves a portable JSON copy, and Export PNG saves a picture of your circuit.
Use Circuit to build and wire your design. For Arduino circuits, open Code, edit the sketch, and start simulation to compile and run it. Select components for their wiring guidance.
Use Robot to configure the motors, robot dimensions, and sensor positions. Open Robot Arena to arrange obstacles, lights, lines, and other arena features, then run simulation to see your wired and programmed robot respond.
Shift-click adds or removes items from a selection. Ctrl/Cmd+A selects all workbench items; Ctrl/Cmd+C / V copies and pastes; R rotates; Delete removes the selection; Esc cancels; Ctrl/Cmd+Z undoes; Ctrl/Cmd+Shift+Z redoes.
Drag empty workbench space to pan and scroll to zoom. Drag a breadboard between its holes to move it with its seated parts. For keyboard placement, activate a component card, use the arrow keys to move, R to rotate, and Enter to place. Use Connect by name for keyboard wiring.
Choose two free terminals or breadboard holes.
Circuit Design and Simulation