esp/rust/04_no-std-aht20/.cargo/config.toml

@@ -0,0 +1,16 @@
+[build]
+target = "xtensa-esp32-espidf"
+
+[target.xtensa-esp32-espidf]
+linker = "ldproxy"
+runner = "espflash flash --monitor"
+rustflags = [ "--cfg",  "espidf_time64"]
+
+[unstable]
+build-std = ["std", "panic_abort"]
+
+[env]
+MCU="esp32"
+# Note: this variable is not used by the pio builder (`cargo build --features pio`)
+ESP_IDF_VERSION = "v5.3.3"
+

esp/rust/04_no-std-aht20/.github/workflows/rust_ci.yml

@@ -0,0 +1,42 @@
+name: Continuous Integration
+
+on:
+  push:
+    branches:
+      - main
+    paths-ignore:
+      - "**/README.md"
+  pull_request:
+  workflow_dispatch:
+
+env:
+  CARGO_TERM_COLOR: always
+  GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+jobs:
+  rust-checks:
+    name: Rust Checks
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        action:
+          - command: build
+            args: --release
+          - command: fmt
+            args: --all -- --check --color always
+          - command: clippy
+            args: --all-targets --all-features --workspace -- -D warnings
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+      - name: Setup Rust
+        uses: esp-rs/xtensa-toolchain@v1.6
+        with:
+          default: true
+          buildtargets: esp32
+          ldproxy: true
+      - name: Enable caching
+        uses: Swatinem/rust-cache@v2
+      - name: Run command
+        run: cargo ${{ matrix.action.command }} ${{ matrix.action.args }}

esp/rust/04_no-std-aht20/.gitignore

@@ -0,0 +1,4 @@
+/.vscode
+/.embuild
+/target
+/Cargo.lock

esp/rust/04_no-std-aht20/Cargo.toml

@@ -0,0 +1,52 @@
+[package]
+name = "aht20"
+version = "0.1.0"
+authors = ["shaun"]
+edition = "2021"
+resolver = "2"
+rust-version = "1.77"
+
+[[bin]]
+name = "aht20"
+harness = false # do not use the built in cargo test harness -> resolve rust-analyzer errors
+
+[profile.release]
+opt-level = "s"
+
+[profile.dev]
+debug = true    # Symbols are nice and they don't increase the size on Flash
+opt-level = "z"
+
+[features]
+default = []
+
+experimental = ["esp-idf-svc/experimental"]
+
+[dependencies]
+log = "0.4"
+esp-idf-svc = "0.51"
+embedded-hal = "1.0.0"
+esp-backtrace = "0.17.0"
+esp-hal = { version = "1.0.0-rc.0", features = ["unstable"] }
+fugit = "0.3.7"
+esp-println = { version = "0.15.0", features = ["log-04"] }
+
+# --- Optional Embassy Integration ---
+# esp-idf-svc = { version = "0.51", features = ["critical-section", "embassy-time-driver", "embassy-sync"] }
+
+# If you enable embassy-time-driver, you MUST also add one of:
+
+# a) Standalone Embassy libs ( embassy-time, embassy-sync etc) with a foreign async runtime:
+# embassy-time = { version = "0.4.0", features = ["generic-queue-8"] } # NOTE: any generic-queue variant will work
+
+# b) With embassy-executor:
+# embassy-executor = { version = "0.7", features = ["executor-thread", "arch-std"] }
+
+# NOTE: if you use embassy-time with embassy-executor you don't need the generic-queue-8 feature
+
+# --- Temporary workaround for embassy-executor < 0.8 ---
+# esp-idf-svc = { version = "0.51", features = ["embassy-time-driver", "embassy-sync"] }
+# critical-section = { version = "1.1", features = ["std"], default-features = false }
+
+[build-dependencies]
+embuild = "0.33"

esp/rust/04_no-std-aht20/README.md

@@ -0,0 +1,3 @@
+https://asairsensors.com/wp-content/uploads/2021/09/Data-Sheet-AHT20-Humidity-and-Temperature-Sensor-ASAIR-V1.0.03.pdf
+
+https://github.com/rust-dd/embedded-dht-rs/tree/main/src

esp/rust/04_no-std-aht20/build.rs

@@ -0,0 +1,3 @@
+fn main() {
+    embuild::espidf::sysenv::output();
+}

esp/rust/04_no-std-aht20/rust-toolchain.toml

@@ -0,0 +1,2 @@
+[toolchain]
+channel = "esp"

esp/rust/04_no-std-aht20/sdkconfig.defaults

@@ -0,0 +1,10 @@
+# Rust often needs a bit of an extra main task stack size compared to C (the default is 3K)
+CONFIG_ESP_MAIN_TASK_STACK_SIZE=8000
+
+# Use this to set FreeRTOS kernel tick frequency to 1000 Hz (100 Hz by default).
+# This allows to use 1 ms granularity for thread sleeps (10 ms by default).
+#CONFIG_FREERTOS_HZ=1000
+
+# Workaround for https://github.com/espressif/esp-idf/issues/7631
+#CONFIG_MBEDTLS_CERTIFICATE_BUNDLE=n
+#CONFIG_MBEDTLS_CERTIFICATE_BUNDLE_DEFAULT_FULL=n

esp/rust/04_no-std-aht20/src/main.rs

@@ -0,0 +1,152 @@
+#![no_std]
+#![no_main]
+
+/// Represents a reading from the sensor.
+pub struct SensorReading<T> {
+    pub humidity: T,
+    pub temperature: T,
+}
+
+/// Possible errors when interacting with the sensor.
+#[derive(Debug)]
+pub enum SensorError {
+    ChecksumMismatch,
+    Timeout,
+    PinError,
+}
+
+pub struct Dht20<I: I2cEmbedded, D: DelayNs> {
+    pub i2c: I,
+    pub delay: D,
+}
+
+impl<I: I2cEmbedded, D: DelayNs> Dht20<I, D> {
+    const SENSOR_ADDRESS: u8 = 0x38;
+
+    pub fn new(i2c: I, delay: D) -> Self {
+        Self { i2c, delay }
+    }
+
+    pub fn read(&mut self) -> Result<SensorReading<f32>, SensorError> {
+        // Check status
+        let mut status_response: [u8; 1] = [0; 1];
+        let _ = self
+            .i2c
+            .write_read(Self::SENSOR_ADDRESS, &[0x71], &mut status_response);
+
+        // Calibration if needed
+        if status_response[0] & 0x18 != 0x18 {
+            let _ = self.i2c.write(Self::SENSOR_ADDRESS, &[0x1B, 0, 0]);
+            let _ = self.i2c.write(Self::SENSOR_ADDRESS, &[0x1C, 0, 0]);
+            let _ = self.i2c.write(Self::SENSOR_ADDRESS, &[0x1E, 0, 0]);
+        }
+
+        // Trigger the measurement
+        self.delay.delay_ms(10);
+        let _ = self.i2c.write(Self::SENSOR_ADDRESS, &[0xAC, 0x33, 0x00]);
+
+        // Read the measurement status
+        self.delay.delay_ms(80);
+        loop {
+            let mut measurement_status_response: [u8; 1] = [0; 1];
+            let _ = self
+                .i2c
+                .read(Self::SENSOR_ADDRESS, &mut measurement_status_response);
+            let status_word = measurement_status_response[0];
+            if status_word & 0b1000_0000 == 0 {
+                break;
+            }
+            self.delay.delay_ms(1);
+        }
+
+        // Read the measurement (1 status + 5 data + 1 crc)
+        let mut measurement_response: [u8; 7] = [0; 7];
+        let _ = self
+            .i2c
+            .read(Self::SENSOR_ADDRESS, &mut measurement_response);
+
+        // Humidity 20 bits (8 + 8 + 4)
+        let mut raw_humidity = measurement_response[1] as u32;
+        raw_humidity = (raw_humidity << 8) + measurement_response[2] as u32;
+        raw_humidity = (raw_humidity << 4) + (measurement_response[3] >> 4) as u32;
+        let humidity_percentage = (raw_humidity as f32 / ((1 << 20) as f32)) * 100.0;
+
+        // Temperature 20 bits
+        let mut raw_temperature = (measurement_response[3] & 0b1111) as u32;
+        raw_temperature = (raw_temperature << 8) + measurement_response[4] as u32;
+        raw_temperature = (raw_temperature << 8) + measurement_response[5] as u32;
+        let temperature_percentage = (raw_temperature as f32 / ((1 << 20) as f32)) * 200.0 - 50.0;
+
+        // Compare the calculated CRC with the received CRC
+        let data = &measurement_response[..6];
+        let received_crc = measurement_response[6];
+        let calculated_crc = Self::calculate_crc(data);
+        if received_crc != calculated_crc {
+            return Err(SensorError::ChecksumMismatch);
+        }
+
+        Ok(SensorReading {
+            humidity: humidity_percentage,
+            temperature: temperature_percentage,
+        })
+    }
+
+    fn calculate_crc(data: &[u8]) -> u8 {
+        let polynomial = 0x31u8; // x^8 + x^5 + x^4 + 1
+        let mut crc = 0xFFu8;
+
+        for &byte in data {
+            crc ^= byte;
+            // CRC8 - process every bit
+            for _ in 0..8 {
+                if crc & 0x80 != 0 {
+                    crc = (crc << 1) ^ polynomial;
+                } else {
+                    crc <<= 1;
+                }
+            }
+        }
+
+        crc
+    }
+}
+
+use embedded_hal::{delay::DelayNs, i2c::I2c as I2cEmbedded};
+use esp_backtrace as _;
+use esp_hal::{
+    clock::CpuClock,
+    delay::Delay,
+    gpio::{Level, Pull},
+    i2c::master::I2c,
+    xtensa_lx_rt::entry,
+};
+use fugit::{ExtU64, HertzU32};
+
+#[entry]
+fn main() -> ! {
+    let peripherals = esp_hal::init(esp_hal::Config::default());
+    esp_println::logger::init_logger_from_env();
+    let mut delay = Delay::new();
+
+    // TODO: Remove unwrap
+    let i2c_for_dht20 =
+        esp_hal::i2c::master::I2c::new(peripherals.I2C0, esp_hal::i2c::master::Config::default())
+            .unwrap()
+            .with_sda(peripherals.pins.gpio21)
+            .with_scl(peripherals.pins.gpio22);
+    let mut dht20 = Dht20::new(i2c_for_dht20, delay);
+
+    loop {
+        delay.delay_ms(5000);
+        match dht20.read() {
+            Ok(sensor_reading) => log::info!(
+                "DHT 20 Sensor - Temperature: {} °C, humidity: {} %",
+                sensor_reading.temperature,
+                sensor_reading.humidity
+            ),
+            Err(error) => log::error!("An error occurred while trying to read sensor: {:?}", error),
+        }
+
+        log::info!("-----");
+    }
+}

esp/rust/README.md

@@ -5,11 +5,30 @@ shaunrd0/klips/esp/rust
 ├── 01_esp-idf-std     # Template project for using ESP-IDF with std enabled.
 ├── 02_esp-gen-no-std  # Template ESP32 project using no std.
 ├── 03_no-std-lcd      # Drawing to LCD using ESP32 no std.
+├── 04_no-std-aht20    # Reading temperature and humidity from a AHT20 sensor using ESP32 no std.
 └── README.md
 ```
 
 ## Development Setup
 
+Install Rust
+
+```bash
+curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
+```
+
+You must run these commands to set up ESP before building any of these examples.
+
+```bash
+sudo apt install python3-venv
+mkdir /tmp/espup && cd /tmp/espup
+cargo install espup --locked
+espup install
+cargo install ldproxy
+sudo usermod -aG dialout $USER
+newgrp dialout
+```
+
 Some notes I took while setting this up for the first time: [Knoats](https://knoats.com/books/esp32/page/rust)
 
 [Espressif Rust book](https://docs.espressif.com/projects/rust/book/introduction.html)