Move back to official crates.io scd4x

.gitignore

@@ -1,5 +1,8 @@
 # Cargo
 target/
 
+# Firmware blobs
+cyw43-firmware/
+
 # VSCode
 .vscode

Cargo.toml

@@ -9,7 +9,7 @@ edition = "2021"
 
 [dependencies]
 # Embassy
-embassy-rp = { version = "0.3.1", features = [
+embassy-rp = { version = "0.4.0", features = [
     "rp235xa",
     "binary-info",
     "critical-section-impl",
@@ -24,12 +24,19 @@ embassy-executor = { version = "0.7.0", features = [
 embassy-time = "0.4.0"
 embassy-embedded-hal = "0.3.0"
 embassy-futures = "0.1.1"
-embassy-sync = "0.6.2"
+embassy-sync = "0.6.2" # TODO: Update when embassy-embedded-hal on crates.io is tracking 0.7.0
+trouble-host = { version = "0.1.0", default-features = false, features = [
+    "peripheral",
+    "gatt",
+    "derive",
+] }
 
 # System
 cortex-m-rt = "0.7.5"
 cortex-m = "0.7.7"
 critical-section = "1.2.0"
+cyw43 = { version = "0.3.0", features = ["bluetooth"] }
+cyw43-pio = "0.4.0"
 rtt-target = "0.6.1"
 
 # embedded-graphics
@@ -37,16 +44,23 @@ embedded-graphics = "0.8.1"
 embedded-graphics-framebuf = "0.5.0"
 
 # Peripherals
-scd4x = { version = "0.4.0", features = ["scd41"] }
+scd4x = { version = "0.4.1", features = ["scd41"] }
 ssd1351 = "0.5.0"
 display-interface-spi = "0.5.0"
 
 # Extra
 static_cell = "2.1.0"
 heapless = "0.8.0"
-circular-buffer = { version = "1.0.0", default-features = false }
+circular-buffer = { version = "1.1.0", default-features = false }
 fixed = "1.29.0"
 
+[build-dependencies]
+reqwest = { version = "0.12.20", features = ["blocking"] }
+
+[features]
+# Skips downloading the Wi-Fi & Bluetooth chipset firmware, assumes that it is in `./cyw43-firmware`
+skip-cyw43-firmware = []
+
 [profile.dev]
 opt-level = "s"
 

README.md

@@ -9,24 +9,33 @@ The effects of increased CO₂ concentration on cognitive function become increa
 ### Prerequisites
 
 - Rust compiler & cargo package manager: https://www.rust-lang.org/
-- RPi Pico SDK: https://github.com/raspberrypi/pico-sdk
-- RPi picotool: https://github.com/raspberrypi/picotool
+- [probe-rs](https://probe.rs/) for programming the device, receiving RTT logging output & debugging
 - ARM bare metal compiler toolchain
     - `arm-none-eabi-gcc` (& `arm-none-eabi-newlib`) on Arch Linux, your system may have different package names
 - The ARMv8 or RISC-V Rust toolchain:
   - ARMv8: `rustup target add thumbv8m.main-none-eabihf`
   - RISC-V: `rustup target add riscv32imac-unknown-none-elf`
 
-### Environment configuration
+### Notes
 
-This build system assumes the environment variables: `PICO_BOARD`, `PICO_PLATFORM` & `PICO_SDK_PATH` are set. `picotool` should also be available in the `PATH`.
+This project's [`Cargo.toml`](./Cargo.toml) includes a custom build profile ("`dist`") which optimises the executable for maximum performance at the cost of slower build times. This profile is designed for flashing a final build onto an end user's device.
 
-The [env-vars.sh](./scripts/env-vars.sh) script sets these values to `pico2_w`, `rp2350-arm-s` and my personal Pico SDK path, respectively. The environment variable definitions in this file can be set with `source ./scripts/env-vars.sh`.
+By install probe-rs as mentioned in the prerequisities you will have access to `cargo flash` and `cargo embed` for flashing the executable onto the device.
 
 ### Compiling & running
 
-- `cargo build` (or `cargo build --release`)
+- `cargo build` (or `cargo build --release` / `cargo build --profile dist`)
 
 If you wish to run the binary on your Pico (connected in BOOTSEL mode):
 
-- `cargo run` (or `cargo run --release`)
+- `cargo run` (or `cargo run --release` / `cargo run --profile dist`)
+
+## Hacking & debugging
+
+This project uses probe-rs for flashing & debugging, though one may use `picotool` and `OpenOCD` instead if you so wish. Ensure that you have a debug probe which supports to RP235x series of chips and supports the SWD protocol. I use the Raspberry Pi debug probe (USB VID:PID `2e8a:000c`) for debugging the device using the on-board debugging pins. 
+
+## TODO / Future improvements
+
+- Companion smartphone app using BLE to receive measurement data from the device for notifications & further analysis/tracking
+- Low-power state, reducing screen brightness, sensor sampling rate and putting periphals to sleep
+- 3D printed case housing the MCU, sensor, display and rechargable lithium ion battery

build.rs

@@ -6,6 +6,9 @@ fn main() {
     let out = PathBuf::from(std::env::var_os("OUT_DIR").unwrap());
     println!("cargo:rustc-link-search={}", out.display());
 
+    #[cfg(not(feature = "skip-cyw43-firmware"))]
+    download_cyw43_firmware();
+
     // ARM build
 
     let memory_x = include_bytes!("memory.x");
@@ -22,3 +25,41 @@ fn main() {
 
     println!("cargo:rerun-if-changed=build.rs");
 }
+
+/// Downloads to firmware for the Wi-Fi / Bluetooth chipset on the RPi Pico 2 W
+#[cfg(not(feature = "skip-cyw43-firmware"))]
+fn download_cyw43_firmware() {
+    let download_folder = "cyw43-firmware";
+    let url_base = "https://raw.githubusercontent.com/embassy-rs/embassy/refs/tags/cyw43-v0.3.0/cyw43-firmware";
+    let file_names = [
+        "43439A0.bin",
+        "43439A0_btfw.bin",
+        "43439A0_clm.bin",
+        "LICENSE-permissive-binary-license-1.0.txt",
+        "README.md",
+    ];
+
+    println!("cargo:rerun-if-changed=build.rs");
+    println!("cargo:rerun-if-changed={}", download_folder);
+    std::fs::create_dir_all(download_folder).expect("failed to create firmware directory");
+
+    // download each file into the directory "cyw43-firmware"
+    for file in file_names {
+        let url = format!("{}/{}", url_base, file);
+        // only fetch if it doesn't exist
+        if std::path::Path::new(download_folder).join(file).exists() {
+            continue;
+        }
+        match reqwest::blocking::get(&url) {
+            Ok(response) => {
+                let content = response.bytes().expect("failed to read file content");
+                let file_path = PathBuf::from(download_folder).join(file);
+                std::fs::write(file_path, &content).expect("failed to write file");
+            }
+            Err(err) => panic!(
+                "failed to download the cyw43 firmware from {}: {}, required for BLE support",
+                url, err
+            ),
+        }
+    }
+}

src/sensor_task.rs

@@ -8,11 +8,15 @@ use scd4x::Scd4x;
 
 use crate::{I2c0BusMutex, SENSOR_DATA_SIGNAL};
 
+const BACKGROUND_CO2_PPM: u16 = 427;
+
 /// Read CO2/temp./humidity data from the sensor
 #[embassy_executor::task]
 pub async fn sensor_read_task(i2c_bus: &'static I2c0BusMutex) {
     debug_rprintln!("Sensor read task started");
 
+    // Initialise SCD41
+
     Timer::after_millis(30).await; // SCD41 power-up delay
     let i2c_dev = I2cDevice::new(i2c_bus);
 
@@ -20,6 +24,11 @@ pub async fn sensor_read_task(i2c_bus: &'static I2c0BusMutex) {
     scd41.wake_up();
     scd41.reinit().unwrap();
 
+    // https://climate.nasa.gov/vital-signs/carbon-dioxide/?intent=121
+    scd41
+        .set_automatic_self_calibration_target(BACKGROUND_CO2_PPM)
+        .unwrap();
+
     match scd41.serial_number() {
         Ok(serial) => debug_rprintln!("[SCD41] Serial number: {}", serial),
         Err(error) => debug_rprintln!(
@@ -28,6 +37,8 @@ pub async fn sensor_read_task(i2c_bus: &'static I2c0BusMutex) {
         ),
     }
 
+    // Measurement loop
+
     scd41.start_periodic_measurement().unwrap();
 
     loop {
@@ -53,4 +64,6 @@ pub async fn sensor_read_task(i2c_bus: &'static I2c0BusMutex) {
             }
         }
     }
+
+    scd41.stop_periodic_measurement().unwrap();
 }