First commit

.cargo/config.toml

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+[build]
+# Set the default target to match the Cortex-M0+ in the RP2040
+target = "thumbv6m-none-eabi"
+
+[target.thumbv6m-none-eabi]
+rustflags = [
+    "-C", "link-arg=--nmagic",
+    "-C", "link-arg=-Tlink.x",
+    "-C", "inline-threshold=5",
+    "-C", "no-vectorize-loops",
+]
+
+runner = "elf2uf2-rs -d"
+

.gitignore

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+/target
+/Cargo.lock

Cargo.toml

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+[package]
+name = "rp-dht"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+embedded-hal = { version = "0.2.5" }
+cortex-m = { version = "0.7.6"}
+cortex-m-rt = "0.7.3"
+rp2040-boot2 = "0.2.1"
+rp2040-hal = { version = "0.9.0", features = ["rp2040-e5"] }
+pio-proc = "0.2.2"
+pio = "0.2.1"
+# embedded-alloc = "0.5.0"

src/dht.pio

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+.program dht
+    ; Clock must be set for 1µs per instruction
+
+    pull block          ; Wait for start
+
+    set x, 31           ; set x register with 31 (for 31 * 32 µS)
+    set pindirs, 1      ; set pin as output
+    set pins, 0         ; set pin to low
+    loop_init_low:      ; wait 992 ms
+        jmp x-- loop_init_low [31]
+
+    set pins, 1         ; set pin to high
+    set pindirs, 0      ; set pin as input
+
+    wait 0 pin 0        ; Wait for low
+    wait 1 pin 0        ; wait for high
+
+    set x, 31               ; Set number bit to received (ignore CRC :( sorry )
+    loop_data:          
+        wait 0 pin 0        ; Wait for low
+        wait 1 pin 0        ; wait for high
+        
+        nop [29]            ; wait for ~ 30 µS
+
+        in pins, 1          ; read the pin state and store bit value
+        
+        jmp x--, loop_data  ; Run until read all bits
+        
+    push                    ; send result

src/lib.rs

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+#![no_std]
+
+use cortex_m::delay::Delay;
+use pio_proc::pio_file;
+use rp2040_hal::gpio::AnyPin;
+use rp2040_hal::pio::{PIOExt, Running, StateMachine, StateMachineIndex, Tx};
+use rp2040_hal::pio::{Rx, UninitStateMachine};
+
+#[derive(Debug)]
+pub enum DhtError {
+    /// DHT never aswer to start signal
+    StartTimout,
+    /// Timeout during communication.
+    Timeout,
+    /// CRC mismatch.
+    CrcMismatch,
+    /// Failed to get pin state (low or high)
+    ReadPinError,
+    /// Internal state error
+    InternatError,
+}
+
+#[derive(Debug)]
+pub struct DhtResult {
+    pub temperature: f32,
+    pub humidity: f32,
+}
+
+pub struct PicoDht<P: PIOExt, STI: StateMachineIndex> {
+    // sm: PicoStateMachine<P, STI>,
+    sm: StateMachine<(P, STI), Running>,
+    rx_fifo: Rx<(P, STI)>,
+    tx_fifo: Tx<(P, STI)>,
+}
+
+impl<P: PIOExt, STI: StateMachineIndex> PicoDht<P, STI> {
+    pub fn new<I: AnyPin<Function = P::PinFunction>>(
+        mut pio: rp2040_hal::pio::PIO<P>,
+        sm: UninitStateMachine<(P, STI)>,
+        dht_pin: I,
+    ) -> Self {
+        let program = pio_file!("./src/dht.pio");
+
+        let pin = dht_pin.into();
+
+        let installed = pio.install(&program.program).unwrap();
+
+        let (int, frac) = (125, 0);
+        let (mut sm, rx, tx) = rp2040_hal::pio::PIOBuilder::from_program(installed)
+            .set_pins(pin.id().num, 1)
+            .clock_divisor_fixed_point(int, frac)
+            .build(sm);
+        sm.set_pindirs([(pin.id().num, rp2040_hal::pio::PinDir::Output)]);
+
+        Self {
+            sm: sm.start(),
+            rx_fifo: rx,
+            tx_fifo: tx,
+        }
+    }
+
+    pub fn read_data(&mut self, delay: &mut Delay) -> Result<DhtResult, DhtError> {
+        let mut timeout = 2000;
+
+        self.tx_fifo.write(1);
+
+        while timeout > 0 && self.rx_fifo.is_empty() {
+            delay.delay_ms(1);
+            timeout -= 1;
+        }
+
+        if timeout <= 0 {
+            self.sm.restart();
+            return Err(DhtError::Timeout);
+        }
+
+        let raw = self.rx_fifo.read().unwrap_or_default();
+
+        let t_raw = raw & 0x0000FFFF;
+        let h_raw = (raw & 0xFFFF0000) >> 16;
+
+        Ok(DhtResult {
+            temperature: t_raw as f32 / 10.0,
+            humidity: h_raw as f32 / 10.0,
+        })
+    }
+}