Example: I2C Sensor Simulation

This example demonstrates how to simulate an I2C peripheral (e.g., TMP102) and verify its behavior using standard Rust firmware.

1. System Configuration

The simulation environment requires defining the sensor in the system manifest and connecting it to the appropriate I2C controller.

Configuration (system.yaml)

chip: "../chips/stm32f103.yaml"
peripherals:
  - id: "i2c1"
    type: "i2c_master"
    base_address: 0x40005400

  - id: "tmp102"
    type: "i2c_temp_sensor"  # Instantiates the TMP102 model
    address: 0x48            # 7-bit I2C address
    bus: "i2c1"              # Connects to the I2C1 controller

2. Firmware Integration

The firmware uses standard HAL calls to interact with the simulated device. No simulation-specific code is required in the firmware itself.

Rust Implementation (stm32f1xx-hal)

use stm32f1xx_hal::{i2c::{BlockingI2c, Mode}, pac};

fn main() -> ! {
    let dp = pac::Peripherals::take().unwrap();
    // ... Clock Configuration ...

    // Initialize I2C1 (Standard Mode, 100kHz)
    let mut i2c = BlockingI2c::i2c1(
        dp.I2C1,
        (scl, sda), // Pins PB6, PB7
        &mut afio.mapr,
        Mode::Standard { frequency: 100.kHz() },
        clocks,
        &mut rcc.apb1,
        1000, 10, 1000, 1000,
    );

    let sensor_addr = 0x48;
    let mut buffer = [0u8; 2];

    loop {
        // Read Temperature Register (0x00)
        i2c.write_read(sensor_addr, &[0x00], &mut buffer).unwrap();

        // Convert to Celsius (12-bit, 0.0625°C resolution)
        let raw_temp = u16::from_be_bytes(buffer) >> 4;
        let celsius = raw_temp as f32 * 0.0625;
    }
}

3. Automated Verification

LabWired supports scripted fault injection to verify error handling logic.

Fault Injection Script (tests/fault_test.yaml)

Simulates a sensor failure or extreme environmental condition.

steps:
  - run: 100ms
  - write_peripheral:
      id: "tmp102"
      reg: "TEMP"
      value: 0x7FF0 # Force sensor reading to 128°C
  - run: 10ms
  - assert_log: "CRITICAL: OVERTEMP DETECTED"

4. Execution

Run the simulation with the test script:

labwired test --script tests/fault_test.yaml

The simulator will execute the firmware, inject the fault at the specified time, and verify that the firmware correctly detects and logs the error condition.