Build and run

Run compiles when needed and starts the selected runtime. Repeated microcontroller runs can reuse matching cached firmware. Build compiles without starting a new simulation. A failed build does not start a new run.

Project / target	Runtime and limits
Arduino ESP32-C3 or UNO R3	Browser simulation; local visible tests and browser debugging are supported.
Arduino ESP32	Its own browser emulator, serial and GPIO; no firmware-visible I²C device support on this engine yet.
Arduino ESP32-S3	Its own browser emulator and UART0; circuit peripheral inputs and browser debugging remain unavailable.
ESP-IDF ESP32 / ESP32-C3	Browser simulation paths exist for their own firmware targets. Use the target-specific starter and supported runtime capabilities.
ESP-IDF ESP32-S3	Target is listed, but builds/browser simulation are unavailable.
Java 21	Browser or remote process execution; JUnit uses the remote session path.

Use Build output for compiler diagnostics and select source locations to investigate. Serial monitor shows microcontroller UART output; Java uses its terminal. Fix the first meaningful diagnostic and run again. A successful compile does not prove every peripheral is modeled.

During simulation, Pause simulator suspends execution, Resume simulator continues, Stop simulator ends the session, and restart/reset starts it afresh. Debug availability depends on the target. Flash is a separate physical-device operation for supported Arduino ESP32 targets.

See IDE controls, Hardware workbench, Java projects, and Supported boards.