esp-idf-hal/examples/rmt_morse_code.rs

//! RMT Transmit Example -- Morse Code
//!
//! To try this out, connect a piezo buzzer via a resistor into pin 17. It should repeat "HELLO"
//! in morse code.
//!
//! Set pin 16 to low to stop the signal and make the buzzer sound "GOODBYE" in morse code.
//!
//! Example loosely based off which has a circuit you can follow.
//! https://github.com/espressif/esp-idf/tree/master/examples/peripherals/rmt/morse_code
//!
//! This example demonstrates:
//! * A carrier signal.
//! * Looping.
//! * Background sending.
//! * Taking a [`Pin`] and [`Channel`] by ref mut, so that they can be used again later.
//!

#[cfg(any(feature = "rmt-legacy", esp_idf_version_major = "4"))]
fn main() -> anyhow::Result<()> {
    example::main()
}

#[cfg(not(any(feature = "rmt-legacy", esp_idf_version_major = "4")))]
fn main() -> anyhow::Result<()> {
    println!("This example requires feature `rmt-legacy` enabled or using ESP-IDF v4.4.X");

    loop {
        std::thread::sleep(std::time::Duration::from_millis(1000));
    }
}

#[cfg(any(feature = "rmt-legacy", esp_idf_version_major = "4"))]
mod example {
    use esp_idf_hal::units::FromValueType;
    use esp_idf_hal::{
        delay::Ets,
        gpio::{OutputPin, PinDriver},
        peripheral::Peripheral,
        prelude::Peripherals,
        rmt::{
            config::{CarrierConfig, DutyPercent, Loop, TransmitConfig},
            PinState, Pulse, PulseTicks, RmtChannel, TxRmtDriver, VariableLengthSignal,
        },
    };

    pub fn main() -> anyhow::Result<()> {
        esp_idf_hal::sys::link_patches();

        let peripherals = Peripherals::take()?;
        let mut channel = peripherals.rmt.channel0;
        let mut led = peripherals.pins.gpio17;
        let stop = peripherals.pins.gpio16;

        let carrier = CarrierConfig::new()
            .duty_percent(DutyPercent::new(50)?)
            .frequency(611.Hz());
        let mut config = TransmitConfig::new()
            .carrier(Some(carrier))
            .looping(Loop::Endless)
            .clock_divider(255);

        let tx = send_morse_code(&mut channel, &mut led, &config, "HELLO ")?;

        let stop = PinDriver::input(stop)?;

        println!("Keep sending until pin {} is set low.", stop.pin());

        while stop.is_high() {
            Ets::delay_ms(100);
        }

        println!("Pin {} set to low. Stopped.", stop.pin());

        // Release pin and channel so we can use them again.
        drop(tx);

        // Wait so the messages don't get garbled.
        Ets::delay_ms(3000);

        // Now send a single message and stop.
        println!("Saying GOODBYE!");
        config.looping = Loop::None;
        send_morse_code(channel, led, &config, "GOODBYE")?;

        Ok(())
    }

    fn send_morse_code<'d>(
        channel: impl Peripheral<P = impl RmtChannel> + 'd,
        led: impl Peripheral<P = impl OutputPin> + 'd,
        config: &TransmitConfig,
        message: &str,
    ) -> anyhow::Result<TxRmtDriver<'d>> {
        println!("Sending morse message '{message}'.");

        let mut signal = VariableLengthSignal::new();
        let pulses = str_pulses(message);
        // We've been collecting `Pulse` but `VariableLengthSignal` needs `&Pulse`:
        let pulses: Vec<&Pulse> = pulses.iter().collect();
        signal.push(pulses)?;

        let mut tx = TxRmtDriver::new(channel, led, config)?;
        tx.start(signal)?;

        // Return `tx` so we can release the pin and channel later.
        Ok(tx)
    }

    enum Code {
        Dot,
        Dash,
        WordGap,
    }

    impl Code {
        pub fn push_pulse(&self, pulses: &mut Vec<Pulse>) {
            match &self {
                Code::Dot => pulses.extend_from_slice(&[high(), low()]),
                Code::Dash => pulses.extend_from_slice(&[high(), high(), high(), low()]),
                Code::WordGap => {
                    pulses.extend_from_slice(&[low(), low(), low(), low(), low(), low()])
                }
            }
        }
    }

    fn high() -> Pulse {
        Pulse::new(PinState::High, PulseTicks::max())
    }

    fn low() -> Pulse {
        Pulse::new(PinState::Low, PulseTicks::max())
    }

    fn find_codes(c: &char) -> &'static [Code] {
        for (found, codes) in CODES.iter() {
            if found == c {
                return codes;
            }
        }
        &[]
    }

    fn str_pulses(s: &str) -> Vec<Pulse> {
        let mut pulses = vec![];
        for c in s.chars() {
            for code in find_codes(&c) {
                code.push_pulse(&mut pulses);
            }

            // Create a gap after each symbol.
            pulses.push(low());
            pulses.push(low());
        }
        pulses
    }

    const CODES: &[(char, &[Code])] = &[
        (' ', &[Code::WordGap]),
        ('A', &[Code::Dot, Code::Dash]),
        ('B', &[Code::Dash, Code::Dot, Code::Dot, Code::Dot]),
        ('C', &[Code::Dash, Code::Dot, Code::Dash, Code::Dot]),
        ('D', &[Code::Dash, Code::Dot, Code::Dot]),
        ('E', &[Code::Dot]),
        ('F', &[Code::Dot, Code::Dot, Code::Dash, Code::Dot]),
        ('G', &[Code::Dash, Code::Dash, Code::Dot]),
        ('H', &[Code::Dot, Code::Dot, Code::Dot, Code::Dot]),
        ('I', &[Code::Dot, Code::Dot]),
        ('J', &[Code::Dot, Code::Dash, Code::Dash, Code::Dash]),
        ('K', &[Code::Dash, Code::Dot, Code::Dash]),
        ('L', &[Code::Dot, Code::Dash, Code::Dot, Code::Dot]),
        ('M', &[Code::Dash, Code::Dash]),
        ('N', &[Code::Dash, Code::Dot]),
        ('O', &[Code::Dash, Code::Dash, Code::Dash]),
        ('P', &[Code::Dot, Code::Dash, Code::Dash, Code::Dot]),
        ('Q', &[Code::Dash, Code::Dash, Code::Dot, Code::Dash]),
        ('R', &[Code::Dot, Code::Dash, Code::Dot]),
        ('S', &[Code::Dot, Code::Dot, Code::Dot]),
        ('T', &[Code::Dash]),
        ('U', &[Code::Dot, Code::Dot, Code::Dash]),
        ('V', &[Code::Dot, Code::Dot, Code::Dot, Code::Dash]),
        ('W', &[Code::Dot, Code::Dash, Code::Dash]),
        ('X', &[Code::Dash, Code::Dot, Code::Dot, Code::Dash]),
        ('Y', &[Code::Dash, Code::Dot, Code::Dash, Code::Dash]),
        ('Z', &[Code::Dash, Code::Dash, Code::Dot, Code::Dot]),
    ];
}