WIP

esp/rust/03_aht20/Cargo.toml

@@ -25,6 +25,11 @@ 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"] }

esp/rust/03_aht20/src/main.rs

@@ -1,10 +1,152 @@
-fn main() {
-    // It is necessary to call this function once. Otherwise some patches to the runtime
-    // implemented by esp-idf-sys might not link properly. See https://github.com/esp-rs/esp-idf-template/issues/71
-    esp_idf_svc::sys::link_patches();
+#![no_std]
+#![no_main]
 
-    // Bind the log crate to the ESP Logging facilities
-    esp_idf_svc::log::EspLogger::initialize_default();
-
-    log::info!("Hello, world!");
+/// 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!("-----");
+    }
 }