diff --git a/rp2040-hal/Cargo.toml b/rp2040-hal/Cargo.toml index bfa3761..0a61392 100644 --- a/rp2040-hal/Cargo.toml +++ b/rp2040-hal/Cargo.toml @@ -45,7 +45,7 @@ panic-halt = "0.2.0" rp2040-boot2 = "0.2.0" hd44780-driver = "0.4.0" pio-proc = "0.1.0" -dht11 = "0.1.0" +dht-sensor = "0.2.1" [features] rt = ["rp2040-pac/rt"] diff --git a/rp2040-hal/examples/dht11.rs b/rp2040-hal/examples/dht11.rs index 503ff68..9253f95 100644 --- a/rp2040-hal/examples/dht11.rs +++ b/rp2040-hal/examples/dht11.rs @@ -1,8 +1,9 @@ -//! # GPIO 'Blinky' Example +//! # DHT11 Example //! -//! This application demonstrates how to control a GPIO pin on the RP2040. +//! This application demonstrates how to read a DHT11 sensor on the RP2040. //! //! It may need to be adapted to your particular board layout and/or pin assignment. +//! In this example, the DHT11 data pin should be connected to GPIO28. //! //! See the `Cargo.toml` file for Copyright and licence details. @@ -40,12 +41,21 @@ pub static BOOT2: [u8; 256] = rp2040_boot2::BOOT_LOADER_W25Q080; /// if your board has a different frequency const XTAL_FREQ_HZ: u32 = 12_000_000u32; -use dht11::Dht11; +use dht_sensor::{dht11, DhtReading}; +/// A wrapper for DynPin, implementing both InputPin and OutputPin, to simulate +/// an open-drain pin as needed by the wire protocol the DHT11 sensor speaks. +/// https://how2electronics.com/interfacing-dht11-temperature-humidity-sensor-with-raspberry-pi-pico/ struct InOutPin { inner: DynPin, } +impl InOutPin { + fn new(inner: DynPin) -> Self { + Self { inner } + } +} + impl InputPin for InOutPin { type Error = rp2040_hal::gpio::Error; fn is_high(&self) -> Result::Error> { @@ -59,10 +69,17 @@ impl InputPin for InOutPin { impl OutputPin for InOutPin { type Error = rp2040_hal::gpio::Error; fn set_low(&mut self) -> Result<(), ::Error> { + // To actively pull the pin low, it must also be configured as a (readable) output pin self.inner.into_readable_output(); - self.inner.set_low() + // In theory, we should set the pin to low first, to make sure we never actively + // pull it up. But if we try it on the input pin, we get Err(Gpio(InvalidPinType)). + self.inner.set_low()?; + Ok(()) } fn set_high(&mut self) -> Result<(), ::Error> { + // To set the open-drain pin to high, just disable the output driver by changing the + // pin to input mode with pull-up. That way, the DHT11 can still pull the data line down + // to send its response. self.inner.into_pull_up_input(); Ok(()) } @@ -73,8 +90,8 @@ impl OutputPin for InOutPin { /// The `#[entry]` macro ensures the Cortex-M start-up code calls this function /// as soon as all global variables are initialised. /// -/// The function configures the RP2040 peripherals, then toggles a GPIO pin in -/// an infinite loop. If there is an LED connected to that pin, it will blink. +/// The function configures the RP2040 peripherals, assigns GPIO 28 to the +/// DHT11 driver, and takes a single measurement. #[entry] fn main() -> ! { // Grab our singleton objects @@ -110,15 +127,15 @@ fn main() -> ! { let mut delay = cortex_m::delay::Delay::new(core.SYST, clocks.system_clock.freq().integer()); - // Configure GPIO 25 as an output - let pin = pins.gpio0.into_push_pull_output(); - let pin = InOutPin { inner: pin.into() }; - - // Create an instance of the DHT11 device - let mut dht11 = Dht11::new(pin); + // Use GPIO 28 as an InOutPin + let mut pin = InOutPin::new(pins.gpio28.into()); + pin.set_high().ok(); // Perform a sensor reading - let _measurement = dht11.perform_measurement(&mut delay).unwrap(); + let _measurement = dht11::Reading::read(&mut delay, &mut pin); + + // In this case, we just ignore the result. A real application + // would do something with the measurement. #[allow(clippy::empty_loop)] loop {