diff --git a/src/laser_diode/analog_wdg.rs b/src/laser_diode/analog_wdg.rs
new file mode 100644
index 0000000..95c3c5d
--- /dev/null
+++ b/src/laser_diode/analog_wdg.rs
@@ -0,0 +1,208 @@
+// stm32f4xx_hal does not provide config and driver for analog watchdog yet
+use stm32f4xx_hal::{
+    pac::{ADC2, NVIC},
+    gpio::{Analog, Output, PushPull, gpioa::PA3, gpiod::PD9},
+    interrupt,
+};
+use uom::si::electric_potential::millivolt;
+use uom::si::f64::ElectricPotential;
+
+// 12 bit Resolution
+const MAX_SAMPLE: u16 = 4095;
+
+pub type LdPwrEnPinType = PD9<Output<PushPull>>;
+pub type PdMonAdcPinType = PA3<Analog>;
+
+static mut ANALOG_WDG: Option<LdAnalogWdg> = None;
+
+pub struct LdAnalogWdgPhy {
+    // To make sure PA3 is configured to Analog mode
+    pub _pd_mon_ch0: PdMonAdcPinType, 
+    pub pwr_en_ch0:  LdPwrEnPinType,
+}
+
+
+#[derive(Clone)]
+pub struct AlarmStatus {
+    alarm: bool,
+    val: u16,
+}
+
+pub struct LdAnalogWdg {
+    pac: ADC2,
+    phy: LdAnalogWdgPhy,
+    alarm_status: AlarmStatus,
+    //Calibrated VDDA in millivolt from Adc<ADC1>.calibrate() 
+    calibrated_vdda: u32, 
+}
+
+impl LdAnalogWdg {
+    /// ADC interrupt is disabled and continuous conversion is started by default
+    pub fn setup(pac: ADC2, phy: LdAnalogWdgPhy){
+        unsafe { ANALOG_WDG = Some(LdAnalogWdg{ 
+            pac: pac, 
+            phy: phy,
+            alarm_status: AlarmStatus {
+                    alarm: false,
+                    val: 0x0000,
+            },
+            calibrated_vdda: 3300,
+            });
+        }
+
+        unsafe {
+            if let Some(ref mut wdg ) = LdAnalogWdg::get() {
+                wdg.pac.cr1.write(|w| w
+                    // 12 Bit Resolution
+                    .res().twelve_bit()
+                    // Enable Analog Watchdog on Single Regular Channel
+                    .awden().enabled()
+                    .awdsgl().single_channel()
+                    .jawden().disabled()
+                    // Disable Analog Watchdog Interrupt
+                    .awdie().disabled()
+                    // Select Analog Watchdog Channel 3 (PA3) on ADC2
+                    .awdch().bits(0x03)
+                );
+                wdg.pac.cr2.write(|w| w
+                    // Continous Conversion mode
+                    .cont().set_bit()
+                    // Enable ADC
+                    .adon().set_bit()
+                    // Start ADC Conversion
+                    .swstart().set_bit()
+                );
+                // Set Sampling Time for Channel 3 to 480 Cycle
+                wdg.pac.smpr2.write(|w| w 
+                    .smp3().cycles480()
+                );
+                // Set the high threshold to be max value initially
+                wdg.pac.htr.write(|w| w.bits(0xFFFF_FFFF));
+                // Set the high threshold to be min value initially
+                wdg.pac.ltr.write(|w| w.bits(0x0000_0000));
+                // Set the Conversion Sequence to only have Channel 3 (PA3)
+                wdg.pac.sqr3.write(|w| w
+                    .sq1().bits(0x03)
+                );
+            }
+        }
+    }
+
+    fn get() -> Option<&'static mut Self> {
+        unsafe { ANALOG_WDG.as_mut() }
+    }
+
+    /// This fn accepts the calibrated vdda value from Adc<ADC1>.calibrate()
+    pub fn set_calibrated_vdda(val: u32) {
+        if let Some(ref mut wdg ) = LdAnalogWdg::get() {
+            wdg.calibrated_vdda = val;
+        }
+    }
+
+    pub fn get_pd_v() -> ElectricPotential {
+        if let Some(ref mut wdg ) = LdAnalogWdg::get() {
+            let sample = wdg.pac.dr.read().data().bits();
+
+            return ElectricPotential::new::<millivolt>(((u32::from(sample) * wdg.calibrated_vdda) / u32::from(MAX_SAMPLE)) as f64)
+        }
+        ElectricPotential::new::<millivolt>(0.0)
+    }
+
+    fn set_alarm(){
+        if let Some(ref mut wdg ) = LdAnalogWdg::get() {
+            wdg.alarm_status = AlarmStatus {
+                alarm: true,
+                val: wdg.pac.dr.read().data().bits(),
+            };
+        }
+    }
+
+    pub fn get_alarm_status() -> AlarmStatus {
+        if let Some(ref mut wdg ) = LdAnalogWdg::get() {
+            return wdg.alarm_status.clone()
+        }
+        AlarmStatus {
+            alarm: false,
+            val: 0x0000,
+        }
+    }
+
+    pub fn clear_alarm_status(){
+        if let Some(ref mut wdg ) = LdAnalogWdg::get() {
+            wdg.alarm_status = AlarmStatus {
+                alarm: false,
+                val: 0x0000,
+            };
+        }
+    }
+
+    /// Set ADC Watchdog Higher threshold register
+    /// Interrupt is triggered when ADC value is ABOVE the value set
+    pub fn set_htr(htr: u32){
+        if let Some(ref mut wdg ) = LdAnalogWdg::get() {
+            wdg.pac.htr.write(|w| unsafe {w.bits(htr)});
+        }
+    }
+
+    /// Set ADC Watchdog Lower threshold register
+    /// Interrupt is triggered when ADC value is BELOW the value set
+    #[allow(unused)]
+    pub fn set_ltr(ltr:u32){
+        if let Some(ref mut wdg ) = LdAnalogWdg::get() {
+            wdg.pac.ltr.write(|w| unsafe {w.bits(ltr)});
+        }
+    }
+
+    pub fn enable_watchdog_interrupt(){
+        if let Some(ref mut wdg ) = LdAnalogWdg::get() {
+            wdg.pac.cr1.modify(|_, w| w
+                .awdie().set_bit()
+            );
+        }
+    }
+
+    pub fn disable_watchdog_interrupt(){
+        if let Some(ref mut wdg ) = LdAnalogWdg::get() {
+            wdg.pac.cr1.modify(|_, w| w
+                .awdie().clear_bit()
+            );
+        }
+    }
+
+    fn clear_interrupt_bit(){
+        unsafe{
+            NVIC::unmask(interrupt::ADC);
+        }
+    }
+
+    pub fn is_pwr_engaged() -> bool{
+        if let Some(ref mut wdg ) = LdAnalogWdg::get() {
+            return wdg.phy.pwr_en_ch0.is_set_high()
+        }
+        false
+    }
+
+    pub fn pwr_engage(){
+        if let Some(ref mut wdg ) = LdAnalogWdg::get() {
+            wdg.phy.pwr_en_ch0.set_high()
+        }
+    }
+
+    pub fn pwr_disengage(){
+        if let Some(ref mut wdg ) = LdAnalogWdg::get() {
+            wdg.phy.pwr_en_ch0.set_low()
+        }
+    }
+}
+
+#[interrupt]
+fn ADC(){
+    cortex_m::interrupt::free(|_| {
+            LdAnalogWdg::set_alarm();
+            LdAnalogWdg::pwr_disengage();
+            // Disable interrupt to avoid getting stuck in infinite interrupt loop
+            LdAnalogWdg::disable_watchdog_interrupt();
+            LdAnalogWdg::clear_interrupt_bit();
+        }
+    )
+}
diff --git a/src/laser_diode/mod.rs b/src/laser_diode/mod.rs
index 8972fe7..59f9016 100644
--- a/src/laser_diode/mod.rs
+++ b/src/laser_diode/mod.rs
@@ -1,5 +1,5 @@
 pub mod ld_ctrl;
 pub mod max5719;
 pub mod laser_diode;
-pub mod pid_state;
-pub mod pd_mon;
\ No newline at end of file
+pub mod pd_mon;
+pub mod analog_wdg;
\ No newline at end of file