diff --git a/src/channels.rs b/src/channels.rs
index 5786310..8667010 100644
--- a/src/channels.rs
+++ b/src/channels.rs
@@ -342,8 +342,6 @@ impl Channels {
                 get(&self.pwm.max_i_neg0),
             (0, PwmPin::MaxV) =>
                 get(&self.pwm.max_v0),
-            (0, PwmPin::Tacho) =>
-                get(&self.pwm.tacho),
             (0, PwmPin::Fan) =>
                 get(&self.pwm.fan),
             (1, PwmPin::MaxIPos) =>
@@ -352,8 +350,6 @@ impl Channels {
                 get(&self.pwm.max_i_neg1),
             (1, PwmPin::MaxV) =>
                 get(&self.pwm.max_v1),
-            (1, PwmPin::Tacho) =>
-                get(&self.pwm.tacho),
             (1, PwmPin::Fan) =>
                 get(&self.pwm.fan),
             _ =>
@@ -485,7 +481,7 @@ impl Channels {
         serde_json_core::to_vec(&summaries)
     }
 
-    fn pwm_summary(&mut self, channel: usize) -> PwmSummary {
+    fn pwm_summary(&mut self, channel: usize, tacho: u32) -> PwmSummary {
         PwmSummary {
             channel,
             center: CenterPointJson(self.channel_state(channel).center.clone()),
@@ -493,15 +489,15 @@ impl Channels {
             max_v: (self.get_max_v(channel), ElectricPotential::new::<volt>(5.0)).into(),
             max_i_pos: self.get_max_i_pos(channel).into(),
             max_i_neg: self.get_max_i_neg(channel).into(),
-            tacho: self.get_pwm(0, PwmPin::Tacho),
+            tacho: tacho * 1000 / 1024,
             fan: self.get_pwm(0, PwmPin::Fan),
         }
     }
 
-    pub fn pwm_summaries_json(&mut self) -> Result<JsonBuffer, serde_json_core::ser::Error> {
+    pub fn pwm_summaries_json(&mut self, tacho: u32) -> Result<JsonBuffer, serde_json_core::ser::Error> {
         let mut summaries = Vec::<_, U2>::new();
         for channel in 0..CHANNELS {
-            let _ = summaries.push(self.pwm_summary(channel));
+            let _ = summaries.push(self.pwm_summary(channel, tacho));
         }
         serde_json_core::to_vec(&summaries)
     }
@@ -592,7 +588,7 @@ pub struct PwmSummary {
     max_v: PwmSummaryField<ElectricPotential>,
     max_i_pos: PwmSummaryField<ElectricCurrent>,
     max_i_neg: PwmSummaryField<ElectricCurrent>,
-    tacho: f64,
+    tacho: u32,
     fan: f64,
 }
 
diff --git a/src/command_handler.rs b/src/command_handler.rs
index 4932975..70857e3 100644
--- a/src/command_handler.rs
+++ b/src/command_handler.rs
@@ -121,8 +121,8 @@ impl Handler {
         Ok(Handler::Handled)
     }
 
-    fn show_pwm(socket: &mut TcpSocket, channels: &mut Channels) -> Result<Handler, Error> {
-        match channels.pwm_summaries_json() {
+    fn show_pwm(socket: &mut TcpSocket, channels: &mut Channels, tacho: u32) -> Result<Handler, Error> {
+        match channels.pwm_summaries_json(tacho) {
             Ok(buf) => {
                 send_line(socket, &buf);
             }
@@ -199,7 +199,6 @@ impl Handler {
                 let current = ElectricCurrent::new::<ampere>(value);
                 channels.set_max_i_neg(channel, current);
             }
-            PwmPin::Tacho => {}
             PwmPin::Fan => {
                 channels.set_pwm(channel, PwmPin::Fan, value);
             }
@@ -345,14 +344,14 @@ impl Handler {
         Ok(Handler::Reset)
     }
 
-    pub fn handle_command (command: Command, socket: &mut TcpSocket, channels: &mut Channels, session: &Session, leds: &mut Leds, store: &mut FlashStore, ipv4_config: &mut Ipv4Config) -> Result<Self, Error> {
+    pub fn handle_command (command: Command, socket: &mut TcpSocket, channels: &mut Channels, session: &Session, leds: &mut Leds, store: &mut FlashStore, ipv4_config: &mut Ipv4Config, tacho_value: u32) -> Result<Self, Error> {
         match command {
             Command::Quit => Ok(Handler::CloseSocket),
             Command::Reporting(_reporting) => Handler::reporting(socket),            
             Command::Show(ShowCommand::Reporting) => Handler::show_report_mode(socket, session),            
             Command::Show(ShowCommand::Input) => Handler::show_report(socket, channels),            
             Command::Show(ShowCommand::Pid) => Handler::show_pid(socket, channels),            
-            Command::Show(ShowCommand::Pwm) => Handler::show_pwm(socket, channels),            
+            Command::Show(ShowCommand::Pwm) => Handler::show_pwm(socket, channels, tacho_value),
             Command::Show(ShowCommand::SteinhartHart) => Handler::show_steinhart_hart(socket, channels),            
             Command::Show(ShowCommand::PostFilter) => Handler::show_post_filter(socket, channels),            
             Command::Show(ShowCommand::Ipv4) => Handler::show_ipv4(socket, ipv4_config),
diff --git a/src/command_parser.rs b/src/command_parser.rs
index 71770de..996d853 100644
--- a/src/command_parser.rs
+++ b/src/command_parser.rs
@@ -127,7 +127,6 @@ pub enum PwmPin {
     MaxIPos,
     MaxINeg,
     MaxV,
-    Tacho,
     Fan
 }
 
diff --git a/src/main.rs b/src/main.rs
index 5be9240..c9ee36a 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -25,6 +25,8 @@ use smoltcp::{
     socket::TcpSocket,
     wire::EthernetAddress,
 };
+use stm32f4xx_hal::gpio::{Edge, ExtiPin};
+use stm32f4xx_hal::syscfg::SysCfgExt;
 
 mod init_log;
 use init_log::init_log;
@@ -102,7 +104,7 @@ fn main() -> ! {
     cp.SCB.enable_icache();
     cp.SCB.enable_dcache(&mut cp.CPUID);
 
-    let dp = Peripherals::take().unwrap();
+    let mut dp = Peripherals::take().unwrap();
     let clocks = dp.RCC.constrain()
         .cfgr
         .use_hse(HSE)
@@ -118,7 +120,7 @@ fn main() -> ! {
 
     timer::setup(cp.SYST, clocks);
 
-    let (pins, mut leds, mut eeprom, eth_pins, usb) = Pins::setup(
+    let (pins, mut leds, mut eeprom, eth_pins, usb, mut tacho) = Pins::setup(
         clocks, dp.TIM1, dp.TIM3, dp.TIM8,
         dp.GPIOA, dp.GPIOB, dp.GPIOC, dp.GPIOD, dp.GPIOE, dp.GPIOF, dp.GPIOG,
         dp.I2C1,
@@ -170,11 +172,18 @@ fn main() -> ! {
     let hwaddr = EthernetAddress(eui48);
     info!("EEPROM MAC address: {}", hwaddr);
 
+    tacho.make_interrupt_source(&mut dp.SYSCFG.constrain());
+    tacho.trigger_on_edge(&mut dp.EXTI, Edge::Rising);
+    tacho.enable_interrupt(&mut dp.EXTI);
+
     net::run(clocks, dp.ETHERNET_MAC, dp.ETHERNET_DMA, eth_pins, hwaddr, ipv4_config.clone(), |iface| {
         Server::<Session>::run(iface, |server| {
             leds.r1.off();
             let mut should_reset = false;
 
+            let (mut tacho_cnt, mut tacho_value) = (0u32, 0u32);
+            let mut prev_epoch = i64::from(timer::now()) >> 10;
+
             loop {
                 let mut new_ipv4_config = None;
                 let instant = Instant::from_millis(i64::from(timer::now()));
@@ -184,6 +193,19 @@ fn main() -> ! {
                 }
 
                 let instant = Instant::from_millis(i64::from(timer::now()));
+                let tacho_input = tacho.check_interrupt();
+                tacho.clear_interrupt_pending_bit();
+                if tacho_input {
+                    tacho_cnt += 1;
+                }
+
+                let epoch = instant.millis >> 10;
+                if epoch > prev_epoch {
+                    tacho_value = tacho_cnt;
+                    tacho_cnt  = 0;
+                    prev_epoch = epoch;
+                }
+
                 cortex_m::interrupt::free(net::clear_pending);
                 server.poll(instant)
                     .unwrap_or_else(|e| {
@@ -206,7 +228,7 @@ fn main() -> ! {
                                 // Do nothing and feed more data to the line reader in the next loop cycle.
                                 Ok(SessionInput::Nothing) => {}
                                 Ok(SessionInput::Command(command)) => {
-                                    match Handler::handle_command(command, &mut socket, &mut channels, session, &mut leds, &mut store, &mut ipv4_config) {
+                                    match Handler::handle_command(command, &mut socket, &mut channels, session, &mut leds, &mut store, &mut ipv4_config, tacho_value) {
                                         Ok(Handler::NewIPV4(ip)) => new_ipv4_config = Some(ip),                                
                                         Ok(Handler::Handled) => {},
                                         Ok(Handler::CloseSocket) => socket.close(),
diff --git a/src/pins.rs b/src/pins.rs
index 9f98ed7..9abadab 100644
--- a/src/pins.rs
+++ b/src/pins.rs
@@ -120,7 +120,7 @@ impl Pins {
         spi2: SPI2, spi4: SPI4, spi5: SPI5,
         adc1: ADC1,
         otg_fs_global: OTG_FS_GLOBAL, otg_fs_device: OTG_FS_DEVICE, otg_fs_pwrclk: OTG_FS_PWRCLK,
-    ) -> (Self, Leds, Eeprom, EthernetPins, USB) {
+    ) -> (Self, Leds, Eeprom, EthernetPins, USB, PC8<Input<Floating>>) {
         let gpioa = gpioa.split();
         let gpiob = gpiob.split();
         let gpioc = gpioc.split();
@@ -138,9 +138,11 @@ impl Pins {
             clocks, tim1, tim3, tim8,
             gpioc.pc6, gpioc.pc7,
             gpioe.pe9, gpioe.pe11,
-            gpioe.pe13, gpioe.pe14, gpioc.pc8, gpioc.pc9
+            gpioe.pe13, gpioe.pe14, gpioc.pc9
         );
 
+       // let tacho = gpioc.pc8.into_floating_input().into_input_pin()();
+
         let (dac0_spi, dac0_sync) = Self::setup_dac0(
             clocks, spi4,
             gpioe.pe2, gpioe.pe4, gpioe.pe6
@@ -215,7 +217,7 @@ impl Pins {
             hclk: clocks.hclk(),
         };
 
-        (pins, leds, eeprom, eth_pins, usb)
+        (pins, leds, eeprom, eth_pins, usb, gpioc.pc8)
     }
 
     /// Configure the GPIO pins for SPI operation, and initialize SPI
@@ -283,12 +285,11 @@ pub struct PwmPins {
     pub max_i_pos1: PwmChannels<TIM1, pwm::C2>,
     pub max_i_neg0: PwmChannels<TIM1, pwm::C3>,
     pub max_i_neg1: PwmChannels<TIM1, pwm::C4>,
-    pub tacho: PwmChannels<TIM8, pwm::C3>,
     pub fan: PwmChannels<TIM8, pwm::C4>,
 }
 
 impl PwmPins {
-    fn setup<M1, M2, M3, M4, M5, M6, M7, M8>(
+    fn setup<M1, M2, M3, M4, M5, M6, M7>(
         clocks: Clocks,
         tim1: TIM1,
         tim3: TIM3,
@@ -299,8 +300,7 @@ impl PwmPins {
         max_i_pos1: PE11<M4>,
         max_i_neg0: PE13<M5>,
         max_i_neg1: PE14<M6>,
-        tacho: PC8<M7>,
-        fan: PC9<M8>,
+        fan: PC9<M7>,
     ) -> PwmPins {
         let freq = 20u32.khz();
 
@@ -317,12 +317,7 @@ impl PwmPins {
         init_pwm_pin(&mut max_v0);
         init_pwm_pin(&mut max_v1);
 
-        let channels = (
-            tacho.into_alternate(),
-            fan.into_alternate(),
-        );
-        let (mut tacho, mut fan) = Timer::new(tim8, &clocks).pwm(channels, freq);
-        init_pwm_pin(&mut tacho);
+        let mut fan = Timer::new(tim8, &clocks).pwm(fan.into_alternate(), freq);
         init_pwm_pin(&mut fan);
 
         let channels = (
@@ -342,7 +337,7 @@ impl PwmPins {
             max_v0, max_v1,
             max_i_pos0, max_i_pos1,
             max_i_neg0, max_i_neg1,
-            tacho, fan
+            fan
         }
     }
 }