diff --git a/src/application/mod.rs b/src/application/mod.rs
index 998aec1..a0699e1 100644
--- a/src/application/mod.rs
+++ b/src/application/mod.rs
@@ -1,10 +1,12 @@
-use cortex_m::prelude::*;
+use cortex_m::{asm::wfi, prelude::*};
 use embedded_hal::digital::v2::{OutputPin, ToggleableOutputPin};
 use nb::{self, block};
 use nmea0183::{ParseResult, Parser};
 use stm32f1xx_hal::{
     delay::Delay,
-    gpio::{gpiob, gpioc, Alternate, Floating, Input, Output, PushPull},
+    gpio::{gpiob, gpioc, Alternate, Floating, Input, OpenDrain, Output, PushPull},
+    i2c::BlockingI2c,
+    pac::I2C1,
     prelude::*,
     serial::Serial,
     stm32,
@@ -18,6 +20,28 @@ pub use setup::setup;
 
 use crate::si5153;
 use crate::time;
+use crate::wspr;
+
+pub struct App {
+    delay: Delay,
+    board_led: gpioc::PC13<Output<PushPull>>,
+    serial: Serial<
+        stm32::USART3,
+        (
+            gpiob::PB10<Alternate<PushPull>>,
+            gpiob::PB11<Input<Floating>>,
+        ),
+    >,
+    i2c: BlockingI2c<
+        I2C1,
+        (
+            gpiob::PB6<Alternate<OpenDrain>>,
+            gpiob::PB7<Alternate<OpenDrain>>,
+        ),
+    >,
+    gps_parser: Parser,
+    locator: arrayvec::ArrayString<6>,
+}
 
 // For PLL with 800MHz
 const WSPR_SYMBOLS: [si5153::PllParams; 4] = [
@@ -51,28 +75,62 @@ const WSPR_SYMBOLS: [si5153::PllParams; 4] = [
     },
 ];
 
-pub struct App {
-    delay: Delay,
-    board_led: gpioc::PC13<Output<PushPull>>,
-    serial: Serial<
-        stm32::USART3,
-        (
-            gpiob::PB10<Alternate<PushPull>>,
-            gpiob::PB11<Input<Floating>>,
-        ),
-    >,
-    gps_parser: Parser,
-    locator: arrayvec::ArrayString<6>,
-}
-
 impl App {
     pub fn run(mut self) -> ! {
+        let callsign = arrayvec::ArrayString::<6>::from("DL1SSK").unwrap();
+
         defmt::info!("Application Startup!");
 
-        let mut last_ts = 0;
+        let mut si_pll = si5153::Si5153::new(&self.i2c);
+        si_pll.init(&mut self.i2c, 25000000, 800000000, 800000000);
+        si_pll.set_ms_source(&mut self.i2c, si5153::Multisynth::MS0, si5153::PLL::A);
+
+        defmt::info!("PLL setup complete.");
+
+        let mut transmitting = false;
+        let mut symbol_start = time::get();
+        let mut symbol_idx: usize = 0;
+        let mut message: [u8; 162] = [0; 162];
 
         loop {
             self.poll_gps();
+
+            if !transmitting {
+                let ts = time::get();
+                if self.locator.len() > 0
+                    && ts.minutes % 2 == 0
+                    && ts.seconds > 1.0
+                    && ts.seconds < 2.0
+                {
+                    defmt::info!("Starting tranmission");
+                    message = wspr::encode_message(&callsign, &self.locator, 27);
+                    symbol_start = ts;
+                    symbol_idx = 0;
+                    si_pll.write_synth_params(
+                        &mut self.i2c,
+                        si5153::Multisynth::MS0,
+                        &WSPR_SYMBOLS[message[symbol_idx] as usize],
+                    );
+                    si_pll.enable_ms_output(&mut self.i2c, si5153::Multisynth::MS0);
+                }
+            } else {
+                let ts = time::get();
+                if (ts.seconds - symbol_start.seconds) >= 0.683 {
+                    symbol_start = ts;
+                    symbol_idx += 1;
+                    if symbol_idx < 162 {
+                        si_pll.write_synth_params(
+                            &mut self.i2c,
+                            si5153::Multisynth::MS0,
+                            &WSPR_SYMBOLS[message[symbol_idx] as usize],
+                        );
+                    } else {
+                        si_pll.disable_ms_output(&mut self.i2c, si5153::Multisynth::MS0);
+                        transmitting = false;
+                    }
+                }
+            }
+            wfi();
         }
 
         //exit();
diff --git a/src/application/setup.rs b/src/application/setup.rs
index 42f57ef..d8a1974 100644
--- a/src/application/setup.rs
+++ b/src/application/setup.rs
@@ -1,5 +1,6 @@
 use stm32f1xx_hal::{
     delay::Delay,
+    i2c,
     pac::Interrupt,
     prelude::*,
     serial::{Config, Serial},
@@ -59,12 +60,30 @@ pub fn setup(cp: cortex_m::peripheral::Peripherals, dp: stm32::Peripherals) -> A
 
     let gps_parser = Parser::new();
 
+    let scl = gpiob.pb6.into_alternate_open_drain(&mut gpiob.crl);
+    let sda = gpiob.pb7.into_alternate_open_drain(&mut gpiob.crl);
+    let mut i2c = i2c::BlockingI2c::i2c1(
+        dp.I2C1,
+        (scl, sda),
+        &mut afio.mapr,
+        i2c::Mode::Standard {
+            frequency: 400_000.hz(),
+        },
+        clocks,
+        &mut rcc.apb1,
+        5,
+        1,
+        5,
+        5,
+    );
+
     time::setup(dp.TIM2, &clocks, &mut rcc.apb1);
 
     App {
         delay,
         board_led,
         serial,
+        i2c,
         gps_parser,
         locator: arrayvec::ArrayString::new(),
     }
diff --git a/src/si5153.rs b/src/si5153.rs
index b327448..b077da2 100644
--- a/src/si5153.rs
+++ b/src/si5153.rs
@@ -150,7 +150,7 @@ where
         }
     }
 
-    pub fn write_params(&self, i2c: &mut I2C, base: u8, params: &PllParams) {
+    fn write_params(&self, i2c: &mut I2C, base: u8, params: &PllParams) {
         let data: [u8; 9] = [
             base,
             ((params.p3 & 0x00FF00) >> 8) as u8,
@@ -168,4 +168,8 @@ where
             panic!("i2c write failed. regAdder: {}", base)
         }
     }
+
+    pub fn write_synth_params(&self, i2c: &mut I2C, synth: Multisynth, params: &PllParams) {
+        self.write_params(i2c, synth.base_address(), params);
+    }
 }
diff --git a/src/wspr.rs b/src/wspr.rs
index cefd7d6..7e0eaeb 100644
--- a/src/wspr.rs
+++ b/src/wspr.rs
@@ -128,7 +128,7 @@ fn add_sync(symbols: &mut [u8; WSPR_LENGTH]) {
     }
 }
 
-pub fn endcode_message(
+pub fn encode_message(
     call_sign: &arrayvec::ArrayString<6>,
     locator: &arrayvec::ArrayString<6>,
     power: u8,
diff --git a/testsuite/tests/wspr.rs b/testsuite/tests/wspr.rs
index e364062..87759fa 100644
--- a/testsuite/tests/wspr.rs
+++ b/testsuite/tests/wspr.rs
@@ -15,7 +15,7 @@ mod tests {
     fn test_encoding() {
         let call_sign = ArrayString::<6>::from(" K1ABC").unwrap();
         let loc = ArrayString::<6>::from("FN42").unwrap();
-        let symbols = wspr::endcode_message(&call_sign, &loc, 37);
+        let symbols = wspr::encode_message(&call_sign, &loc, 37);
 
         let expected_symbols: [u8; 162] = [
             3, 3, 0, 0, 2, 0, 0, 0, 1, 0, 2, 0, 1, 3, 1, 2, 2, 2, 1, 0, 0, 3, 2, 3, 1, 3, 3, 2, 2,