bme680-driver

Table of Contents

• Overview
• Features
• Repository Structure
• Installation
• Quick Start
• Units & Precision
• License

Overview

A type-safe, no_std Rust driver for the Bosch BME680 environmental sensor. It provides high-level access to temperature, humidity, atmospheric pressure, and gas resistance measurements using the embedded-hal traits.

Features

• Power Saving: Individually enable/disable gas, pressure, temperature, or humidity measurements to reduce power consumption.
• Typestate Pattern: Prevents illegal sensor states and ensures correct initialization.
• Fixed-Point Arithmetic: High-performance compensation formulas without the need for a floating-point unit (FPU).
• Type-Safe Units: Uses custom types like Celsius and Milliseconds to prevent unit-mixing errors.
• No-Std: Suitable for all bare-metal microcontrollers (STM32, ESP32, AVR, etc.).

Repository Structure

└── bme680-driver/
    ├── src/
    │   ├── lib.rs
    │   ├── calc.rs
    │   └── settings.rs
    ├── examples/
    │   └── stm32f407.rs
    ├── .cargo/
    │   └── config.toml
    └── Cargo.toml

Installation

Add this to your Cargo.toml:

[dependencies]
bme680-driver = "0.3.0"

Quick Start (STM32 Example)

use bme680_driver::*;

// --- 1. Sensor-Konfiguration via Builder ---
// Wir definieren ein Profil für die Gassensor-Heizplatte.
let gas_profile = GasProfile {
    index: GasProfileIndex::Profile0,
    target_temp: Celsius(300),      // Ziel: 300°C
    wait_time: Milliseconds(300),   // 300ms Aufheizzeit
};

let config = BME680Builder::new()
    .temp_oversampling(Oversampling::X2)
    .hum_oversampling(Oversampling::X1)
    .pres_oversampling(Oversampling::Skipped) // Druckmessung deaktiviert
    .gas_profile(Some(gas_profile))
    .ambient_temp(Celsius(2100))    // Erste Schätzung: 21.00°C
    .build();

// --- 2. Initialisierung (Typestate: Uninitialized -> Ready) ---
// I2C und Delay kommen von deinem HAL (z.B. stm32f4xx-hal)
let mut bme = Bme680::with_config(i2c, 0x76, config)
    .init(&mut delay)
    .expect("BME680 Init fehlgeschlagen");

// Tracking für die Heizungskompensation
let mut last_heater_update_temp = Celsius(2100);

loop {
    // Messung triggern (wartet automatisch auf die Heizphase)
    let data = bme.read_new_data(&mut delay).unwrap();
    
    // Daten formatieren ohne Floats (Festkomma-Arithmetik)
    let (t_int, t_frac) = data.temp.split();
    let (h_int, h_frac) = data.hum.split();
    
    defmt::println!("Temp: {}.{} °C", t_int, t_frac);
    defmt::println!("Hum:  {}.{} %", h_int, h_frac);
    
    if data.gas.0 > 0 {
        defmt::println!("Gas:  {} Ohm", data.gas.0);
    }

    // --- Dynamische Heizungskompensation ---
    // Wir aktualisieren die Heizparameter nur bei signifikanten Temp-Änderungen (> 2°C),
    // um chemische Instabilitäten (Sprünge) im Gassensor zu vermeiden.
    if (data.temp.0 - last_heater_update_temp.0).abs() >= 2000 {
        bme.update_ambient_temp(data.temp).unwrap();
        last_heater_update_temp = data.temp;
        defmt::info!("Heizprofil an neue Umgebungstemperatur angepasst.");
    }
    
    delay.delay_ms(5000);
}

Units and Precision

License

Licensed under either of:

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)

• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.