Drive the built-in LED low after turning it on.
Arduino / C: digitalWrite changes the actual output level of a configured pin.
void setup() {
Serial.begin(9600);
pinMode(LED_BUILTIN,OUTPUT);digitalWrite(LED_BUILTIN,HIGH);delay(5);
digitalWrite(LED_BUILTIN,LOW);Serial.println("off");
}
void loop() {
}Expected output EXAMPLE
off
Details
Targets Arduino Uno R3 (ATmega328P, 16 MHz) with the Arduino AVR core. Open as a sketch in the Arduino IDE and select Arduino Uno. Serial output uses 9600 baud. Tested with simavr; electrical characteristics and physical wiring are outside this simulation. digitalWrite changes the actual output level of a configured pin.
Tested on Ubuntu 24.04.5 LTS · · Uno R3 / ATmega328P at 16 MHz; simavr 1.6+dfsg-3build2 · bash 5.2.21-2ubuntu4; coreutils 9.4-3ubuntu6.3; arduino-cli Version: 1.5.1 Commit: 01f3d4f2b Date: 2026-06-05T10:22:17Z; Arduino AVR core 1.8.6
Test inputs, results and environment
The exact published code ran in a dedicated Linux test container with prepared inputs. Snippet process uid 65534 with a read-only root filesystem and temporary working files. Networking disabled. The exact sketch was compiled for Uno R3 and simulated at 16 MHz. UART output is shown below; compiler logs and measured GPIO traces are retained in the test evidence. Fixtures and output records are isolated from the application database. Testing covers this example and its stated checks, not every input, operating system, or runtime version. The Linux container shares its host's kernel; this is not a native Windows test.
- Architecture / host kernel
- x86_64 / 6.18.54.1-microsoft-standard-WSL2
- Snippet identity / locale
- uid=65534, gid=65534 (unprivileged process) / C.UTF-8
- Interpreter invocation
arduino-cli compile --fqbn arduino:avr:uno; uno-sim sketch.ino.elf (capture UART and D13 transitions)- Container image ID
sha256:ec91410a8f6ec3e985830b5e3a0560306d36f8c1c5ccd91a6699abe707123fa3- Code SHA-256
1ffdea65179f37e3bb2dd25d4a1936fef257760ad7bf5b0600544f479ac85cc5- Dependencies
- bash 5.2.21-2ubuntu4; coreutils 9.4-3ubuntu6.3; arduino-cli Version: 1.5.1 Commit: 01f3d4f2b Date: 2026-06-05T10:22:17Z; Arduino AVR core 1.8.6
Test input setup
These are the prepared inputs used by the test harness. See Details above for the prerequisites and how to run this example.
Simulator inputs: {"sim_ms": 500, "serial_input": "", "pin_input": "none"}
Observed standard output
off
Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.
Additional assertions that passed
Checks recorded by the test harness. Where Python assertions are shown, browser cases use Playwright and simulator cases may inspect pin transitions: result.stdout is captured output, work is the temporary directory, and Path is pathlib.Path. The harness also imports json and csv.
trace=[tuple(map(int,line.split(','))) for line in Path('pin13.csv').read_text().splitlines()]
assert any(v==1 for c,v in trace) and trace[-1][1]==0