CircuiteraChoose the Uno R3 target
Select Arduino Uno R3 before pressing Verify. Circuitera compiles for the 16 MHz ATmega328P using the standard Arduino pin variant. The profile provides 32,256 bytes of application flash and 2,048 bytes of SRAM. The build summary reports program storage and static RAM separately; the running sketch also needs space for its stack and dynamically allocated data.
Start with pins you can check
Use LED_BUILTIN for an onboard Blink test. Uno R3 exposes digital pins D0–D13 and analog inputs A0–A5. PWM is available on D3, D5, D6, D9, D10, and D11. A4 and A5 serve I2C SDA and SCL. Consult the IDE’s pin helper before wiring, and use a current-limiting resistor for an external LED.
Upload and inspect the result
With a successful build, connect a USB data cable and choose the board’s port in Connect board. The Uno profile uses its serial bootloader for upload and reads firmware back to verify it. Keep D0/D1 clear of devices that interfere with the serial connection. Open Serial Monitor at the baud rate in Serial.begin() to read values from the sketch.
Match the board, not just its name
This guide covers Uno R3 with ATmega328P. Uno R4 has a different processor and is not supported by this AVR profile. Clones may use a different USB bridge or bootloader; a port name alone cannot prove the MCU. For supported circuits, the simulator can help explore behavior, but real wiring and hardware still need checking.