diff --git a/src/beep.rs b/src/beep.rs
new file mode 100644
index 0000000..e295ccd
--- /dev/null
+++ b/src/beep.rs
@@ -0,0 +1,108 @@
+use embedded_svc::timer::{PeriodicTimer, TimerService};
+use esp_idf_hal::gpio::{Gpio4, Output};
+use esp_idf_hal::ledc::{config::TimerConfig, Channel, Timer};
+use esp_idf_hal::ledc::{CHANNEL0, TIMER0};
+use esp_idf_hal::prelude::*;
+use esp_idf_svc::timer::{EspTimer, EspTimerService};
+use esp_idf_sys::EspError;
+use log::{info, warn};
+use std::sync::{Arc, Mutex};
+use std::time::Duration;
+type LedcChannel<P, T, C> = Channel<C, T, Timer<T>, P>;
+
+#[derive(Clone, Copy, Debug)]
+struct BeepState {
+    beat: u8,
+    ringtone: ringtone::Type,
+}
+
+impl BeepState {
+    pub fn new() -> Self {
+        Self {
+            beat: 0,
+            ringtone: ringtone::SILENCE,
+        }
+    }
+    pub fn from_ringtone(ringtone: ringtone::Type) -> Self {
+        Self { beat: 0, ringtone }
+    }
+}
+
+pub struct Beep {
+    watch_timer: Option<EspTimer>,
+    state: BeepState,
+}
+impl Beep {
+    pub fn new() -> Self {
+        return Beep {
+            watch_timer: None,
+            state: BeepState::new(),
+        };
+    }
+    fn init_channel(
+        pin: Gpio4<Output>,
+        timer: TIMER0,
+        channel: CHANNEL0,
+        frequency: Hertz,
+    ) -> Result<LedcChannel<Gpio4<Output>, TIMER0, CHANNEL0>, EspError> {
+        let config = TimerConfig::default().frequency(frequency);
+        let timer = Timer::new(timer, &config)?;
+        let channel = Channel::new(channel, timer, pin)?;
+        return Ok(channel);
+    }
+    pub fn play(&mut self, ringtone: ringtone::Type) -> anyhow::Result<()> {
+        if self.state.ringtone != ringtone {
+            self.state = BeepState::from_ringtone(ringtone);
+        }
+        let state = Arc::new(Mutex::new(self.state));
+        let mut timer = EspTimerService::new()?.timer(move || {
+            info!("One-shot timer triggered");
+            match state.lock().as_mut() {
+                Ok(state) => {
+                    info!("B state.beat: {}", state.beat);
+                    if let Err(err) = Self::play_once(state) {
+                        warn!("{}", err);
+                    }
+                    info!("A state.beat: {}", state.beat);
+                }
+                Err(err) => {
+                    warn!("Failed to lock state. {}", err);
+                }
+            }
+        })?;
+        timer.every(Duration::from_millis(250))?;
+
+        self.watch_timer = Some(timer);
+        return anyhow::Ok(());
+    }
+
+    fn play_once(state: &mut BeepState) -> anyhow::Result<()> {
+        let pin = unsafe { Gpio4::<Output>::new() }
+            .into_output()
+            .map_err(|err| anyhow::anyhow!("Failed to set GPIO 4 as ledc output. {}", err))?;
+        let hw_timer = unsafe { TIMER0::new() };
+        let hw_channel = unsafe { CHANNEL0::new() };
+        let curr = state.ringtone[state.beat as usize];
+        let mut channel = Self::init_channel(pin, hw_timer, hw_channel, if curr < 1000 { 1000.Hz().into()} else  {curr.Hz().into()} )
+            .map_err(|err| anyhow::anyhow!("Failed to initialize channel. {}", err))?;
+
+        if curr < 1000 {
+            channel.set_duty(0).expect("Failed to set duty");
+        } else {
+            channel.set_duty(60).expect("Failed to set duty");
+        }
+
+        state.beat += 1;
+        if state.beat == 16 {
+            state.beat = 0;
+        }
+        return anyhow::Ok(());
+    }
+}
+pub mod ringtone {
+    pub type Type = [u32; 16];
+    pub const ADAPTER_DOWN: Type = [2000, 1950, 1900, 1800, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0];
+    pub const BATTERY_LOW: Type = [2000, 1950, 0, 0, 1930, 1900, 0, 0, 2000, 1900, 0, 0, 1930, 1900, 0, 0];
+    pub const SILENCE: Type = [0; 16];
+    pub const SHUTDOWN: Type = [2300, 0, 2300, 2000, 2100, 2000, 0, 2300, 2000, 2100, 2000, 1900, 0, 0, 0, 0];
+}
diff --git a/src/main.rs b/src/main.rs
index 082a88d..fddf1e1 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -8,13 +8,14 @@ use std::{
     time::Duration,
 };
 
+mod beep;
 mod blink;
 mod message_queue;
 mod time;
 mod voltage_detection;
 mod wifi;
 
-use crate::voltage_detection::VoltageDetectionWorker;
+use crate::{beep::{Beep, ringtone}, voltage_detection::VoltageDetectionWorker};
 use crate::{
     message_queue::MessageQueue, time::Time, voltage_detection::VoltageDetection, wifi::Internet,
 };
@@ -58,6 +59,8 @@ fn main() {
         );
         blink.play();
     });
+    let mut beep = Beep::new();
+    beep.play(ringtone::ADAPTER_DOWN).expect("Can not beep.");
 
     let mut voltage_detection = VoltageDetection::new();
 
@@ -89,19 +92,5 @@ fn main() {
 
     loop {
         sleep(Duration::from_millis(1000));
-        // if let Some(ref mut mq_client) = mq.client {
-        //     let timestamps = time.get_time().as_millis();
-
-        //     info!("timestamps {}", timestamps);
-        //     mq_client
-        //         .publish(
-        //             "ups-0.2/heartbeat",
-        //             QoS::AtMostOnce,
-        //             false,
-        //             timestamps.to_string().as_bytes(),
-        //         )
-        //         .map_err(|err| warn!("publish heartbeat failed {}", err))
-        //         .unwrap();
-        // }
     }
 }