diff --git a/src/wspr.c b/src/wspr.c
new file mode 100644
--- /dev/null
+++ b/src/wspr.c
@@ -0,0 +1,109 @@
+#include "stm32f0xx_hal.h"
+#include "si5351.h"
+#include "jtencode.h"
+#include "gpio.h"
+#include "wspr.h"
+#include "config.h"
+
+
+#define WSPR_DEFAULT_FREQ 10140100UL
+#define WSPR_TONE_SPACING 146 // ~1.46 Hz
+#define WSPR_CTC 10672 // CTC value for WSPR
+
+// Test stuff
+char call[7] = "KD8TDF";
+char loc[5] = "EN72";
+uint8_t dbm = 10;
+uint8_t tx_buffer[255];
+
+// Frequencies and channel info
+uint32_t freq = WSPR_DEFAULT_FREQ;
+uint8_t symbol_count = WSPR_SYMBOL_COUNT;
+uint16_t ctc = WSPR_CTC;
+uint16_t tone_spacing = WSPR_TONE_SPACING;
+volatile uint8_t proceed = 0;
+
+TIM_HandleTypeDef htim1;
+
+
+
+void wspr_init(void)
+{
+    // Start timer for WSPR
+    __TIM1_CLK_ENABLE();
+    htim1.Instance = TIM1;
+    htim1.Init.Prescaler = 512; // gives 64uS ticks from 8MHz ahbclk
+    htim1.Init.CounterMode = TIM_COUNTERMODE_UP;
+    htim1.Init.Period = ctc; // Count up to this value (how many 64uS ticks per symbol)
+    htim1.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
+    htim1.Init.RepetitionCounter = 0;
+    HAL_TIM_Base_Init(&htim1);
+    HAL_TIM_Base_Start_IT(&htim1);
+    HAL_NVIC_SetPriority(TIM1_BRK_UP_TRG_COM_IRQn, 0, 0);
+    HAL_NVIC_EnableIRQ(TIM1_BRK_UP_TRG_COM_IRQn);
+
+}
+
+// Do anything needed to prepare for sleep
+void wspr_sleep(void)
+{
+    HAL_TIM_Base_Stop_IT(&htim1);
+}
+
+void wspr_wakeup(void)
+{
+    HAL_TIM_Base_Start_IT(&htim1);
+}
+
+
+// Bring up TCXO and oscillator IC
+void wspr_transmit(void)
+{
+    HAL_GPIO_WritePin(OSC_NOTEN, 0);
+    HAL_GPIO_WritePin(TCXO_EN, 1);
+    HAL_Delay(100);
+
+    // Bring up the chip
+    si5351_init(i2c_get(), SI5351_CRYSTAL_LOAD_8PF, 0);
+    si5351_set_correction(0);
+    //si5351_set_pll(SI5351_PLL_FIXED, SI5351_PLLA);
+    //si5351_set_ms_source(SI5351_CLK0, SI5351_PLLA);
+    si5351_set_freq(WSPR_DEFAULT_FREQ * 100, 0, SI5351_CLK0);
+    si5351_drive_strength(SI5351_CLK0, SI5351_DRIVE_8MA); // Set for max power if desired (8ma max)
+    si5351_output_enable(SI5351_CLK0, 1);
+    //si5351_pll_reset(SI5351_PLLA);
+
+    // Make sure the other outputs of the SI5351 are disabled
+    si5351_output_enable(SI5351_CLK1, 0); // Disable the clock initially
+    si5351_output_enable(SI5351_CLK2, 0); // Disable the clock initially
+
+    // disable clock powers
+    si5351_set_clock_pwr(SI5351_CLK1, 0);
+    si5351_set_clock_pwr(SI5351_CLK2, 0);
+
+
+    // Encode message to transmit
+    wspr_encode(call, loc, dbm, tx_buffer);
+
+    // Key transmitter
+    si5351_output_enable(SI5351_CLK0, 1);
+
+    // Loop through and transmit symbols TODO: Do this from an ISR or ISR-triggered main loop function call (optimal)
+    uint8_t i;
+    for(i=0; i<symbol_count; i++)
+    {
+        uint32_t freq2 = (freq * 100) + (tx_buffer[i] * tone_spacing);
+        si5351_set_freq(freq2, 0, SI5351_CLK0);
+        HAL_GPIO_TogglePin(LED_BLUE);
+
+        proceed = 0;
+        while(!proceed);
+    }
+
+    // Disable transmitter
+    si5351_output_enable(SI5351_CLK0, 0);
+
+    HAL_GPIO_WritePin(OSC_NOTEN, 1);
+    HAL_GPIO_WritePin(TCXO_EN, 0);
+}
+