diff --git a/Libraries/Si446x/si446x.c b/Libraries/Si446x/si446x.c
new file mode 100644
--- /dev/null
+++ b/Libraries/Si446x/si446x.c
@@ -0,0 +1,427 @@
+//
+// Si446x: Initializes and configures a Si446x transceiver over SPI
+//
+
+#include "stm32f0xx_hal.h"
+
+#include "si446x.h"
+#include "config.h"
+#include "error.h"
+#include "system/gpio.h"
+#include "system/sysclk.h"
+
+
+// Private variables
+static SPI_HandleTypeDef hspi1;
+static uint8_t si446x_cw_status = 0;
+
+
+// Private function prototypes
+static void __init_spi1(void);
+
+
+// Initialize Si446x in 2FSK transmit mode
+void si446x_init(void)
+{
+	// init spi port
+	__init_spi1();
+
+	GPIO_InitTypeDef GPIO_InitStruct;
+
+	// GPIO: TCXO control
+	GPIO_InitStruct.Pin = SI446x_TCXO_EN_PIN;
+	GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
+	GPIO_InitStruct.Pull = GPIO_NOPULL;
+	HAL_GPIO_Init(SI446x_TCXO_EN_PORT, &GPIO_InitStruct);
+	HAL_GPIO_WritePin(SI446x_TCXO_EN_PORT, SI446x_TCXO_EN_PIN, 1);
+
+	// GPIO: VHF radio shutdown control
+	GPIO_InitStruct.Pin = SI446x_SHUTDOWN_PIN;
+	GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
+	GPIO_InitStruct.Pull = GPIO_NOPULL;
+	HAL_GPIO_Init(SI446x_SHUTDOWN_PORT, &GPIO_InitStruct);
+
+	// Perform PoR (takes 20ms) and turn device on
+	si446x_reset();
+
+    // Divide SI446x_VCXO_FREQ into its bytes; MSB first
+    uint16_t x3 = SI446x_VCXO_FREQ / 0x1000000;
+    uint16_t x2 = (SI446x_VCXO_FREQ - x3 * 0x1000000) / 0x10000;
+    uint16_t x1 = (SI446x_VCXO_FREQ - x3 * 0x1000000 - x2 * 0x10000) / 0x100;
+    uint16_t x0 = (SI446x_VCXO_FREQ - x3 * 0x1000000 - x2 * 0x10000 - x1 * 0x100);
+
+    // Power up radio module                          boot  xtal  _XO_frequency_
+
+    //TCXO
+    const char init_command[] = {SI446x_CMD_POWER_UP, 0x01, 0x01, x3, x2, x1, x0};
+    si446x_sendcmd(7, init_command, SI446x_CHECK_ACK);
+
+    HAL_Delay(10);
+
+	// Change to SPI Ready state EMZ added for re-init, might help on startup
+	uint8_t change_state_commanda[] = {SI446x_CMD_CHANGE_STATE, 0x02}; //  Change to spi ready
+    si446x_sendcmd(2, change_state_commanda, SI446x_CHECK_ACK);
+    HAL_Delay(10);
+
+    // Radio ready: clear all pending interrupts and get the interrupt status back
+	uint8_t get_int_status_command[] = {SI446x_CMD_GET_INT_STATUS, 0x00, 0x00, 0x00};
+    si446x_sendcmd(4, get_int_status_command, SI446x_CHECK_ACK);
+
+    HAL_Delay(10);
+
+    // GPIO config: Set all GPIOs LOW; Link NIRQ to CTS; Link SDO to MISO; Max drive strength
+	uint8_t gpio_pin_cfg_command[] = {
+    		SI446x_CMD_GPIO_PIN_CFG, // Command
+			SI446x_GPIO_LOW,      // GPIO0 - Power amp control DAC AD5611 Sync Pin
+			SI446x_GPIO_INPUT,    // GPIO1 - Input for modulation
+			SI446x_GPIO_LOW,      // GPIO2 - Blue LED
+			SI446x_GPIO_NOCHANGE, // GPIO3 - Unused
+			SI446x_GPIO_NOCHANGE, // NIRQ
+			SI446x_GPIO_NOCHANGE, // 0x11, // SDO
+			SI446x_GPIO_NOCHANGE, // Gencfg
+	};
+    si446x_sendcmd(8, gpio_pin_cfg_command, SI446x_CHECK_ACK);
+
+    HAL_Delay(10);
+
+//	uint8_t tune_xo_cmd[] = {
+//    		SI446x_CMD_SET_PROPERTY,
+//			SI446x_XO_TUNE_REGISTER_GROUP,
+//			0x1, // num data
+//			SI446x_XO_TUNE_REGISTER_PROP,
+//			SI446x_CRYSTAL_LOAD_TUNING,
+//    };
+//    si446x_sendcmd(5, tune_xo_cmd, SI446x_CHECK_ACK);
+
+    HAL_Delay(10);
+
+    // Tune to frequency specified
+	si446x_setchannel(TUNE_FREQUENCY);
+
+	HAL_Delay(10);
+
+    // Set to 2FSK mode
+    uint8_t modemconfig = SI446x_MOD_TYPE_2FSK | SI446x_MOD_TYPE_SOURCE_DIRECTMODE | SI446x_MOD_TYPE_DIRECT_ASYNCH | SI446x_MOD_TYPE_DIRECT_SOURCE_GPIO1; //SI446x_MOD_TYPE_SOURCE_PACKETHANDLER
+    uint8_t set_modem_mod_type_command[] = {
+    		SI446x_CMD_SET_PROPERTY,
+    		SI446x_MOD_TYPE_REGISTER_GROUP,
+			0x01, // num data
+			SI446x_MOD_TYPE_REGISTER_PROP,
+			modemconfig
+    };
+    si446x_sendcmd(5, set_modem_mod_type_command, SI446x_CHECK_ACK);
+
+    HAL_Delay(10);
+
+	// Set Si446x initial output power, input to power amp (0-0x7F, 0mW - 40mw?)
+	uint8_t basepower = 0x02;
+	// FIXME: basepower should be 0x10 for underperforming units and 0x04 for normal units
+    uint8_t set_power_level_command[] = {SI446x_CMD_SET_PROPERTY, 0x22, 0x01, 0x01, basepower};
+	si446x_sendcmd(5, set_power_level_command, SI446x_CHECK_ACK);
+
+
+	HAL_Delay(10);
+
+    // Set air data rate
+    si446x_setdatarate();
+    HAL_Delay(10);
+
+	// Tune TX
+	uint8_t change_state_command[] = {SI446x_CMD_CHANGE_STATE, 0x05}; //  Change to TX tune state
+    si446x_sendcmd(2, change_state_command, SI446x_CHECK_ACK);
+    HAL_Delay(10);
+
+	si446x_cw_status = 0;
+
+	si446x_cw_on();
+}
+
+
+// Perform power-on-reset of Si446x. Takes 20ms.
+void si446x_reset(void)
+{
+	si446x_shutdown();
+	HAL_Delay(10);
+	si446x_wakeup();
+	HAL_Delay(10);
+}
+
+
+// Set GPIO pin state on Si446x
+void si446x_gpio(uint8_t gpio, uint8_t state, uint8_t doack)
+{
+	// GPIO invalid
+	if(gpio > 7)
+		return;
+
+	// Default to not changing any GPIO
+	uint8_t gpio_pin_cfg_command[] = {
+			SI446x_CMD_GPIO_PIN_CFG, // Command
+			SI446x_GPIO_NOCHANGE, // GPIO0 - Power amp control DAC AD5611 Sync Pin
+			SI446x_GPIO_NOCHANGE, // GPIO1 - Input for modulation
+			SI446x_GPIO_NOCHANGE, // GPIO2 - Blue
+			SI446x_GPIO_NOCHANGE, // GPIO3 - Unused
+			SI446x_GPIO_NOCHANGE, // NIRQ
+			SI446x_GPIO_NOCHANGE, // 0x11, // SDO
+			SI446x_GPIO_NOCHANGE, // Gencfg
+	};
+
+	// Set requested GPIO to requested state
+	gpio_pin_cfg_command[gpio+1] = state;
+
+	si446x_sendcmd(8, gpio_pin_cfg_command, doack);
+}
+
+
+// Set over-air data rate
+void si446x_setdatarate(void)
+{
+    // Set data rate (unsure if this actually affects direct modulation)
+                         //        set prop   group     numprops  startprop   data
+	uint8_t set_data_rate_command[] = {SI446x_CMD_SET_PROPERTY,     0x20,     0x03,     0x03,       0x0F, 0x42, 0x40};
+    si446x_sendcmd(7, set_data_rate_command, SI446x_CHECK_ACK);
+}
+
+
+// Block write data to the Si446x SPI interface, up to 128 byte length
+void si446x_senddata(uint8_t* data, uint8_t len)
+{
+	uint8_t dummy[128];
+	SI446x_SELECT;
+	HAL_SPI_TransmitReceive(&hspi1, data, dummy, len, SI446x_TIMEOUT);
+	SI446x_DESELECT;
+}
+
+
+// Delay approximately 20us
+static void delay_cycles(void)
+{
+	uint32_t delay_cycles = 180;
+	while(delay_cycles>0)
+	{
+		asm("NOP");
+		delay_cycles--;
+	}
+}
+
+
+// Send a command to the radio (Blocking)
+// Avoid calling this during code runtime as it will block for a significant period of time due to delays
+void si446x_sendcmd(uint8_t tx_len, uint8_t* data, uint8_t doack)
+{
+    SI446x_SELECT;
+
+    delay_cycles();
+
+    uint8_t dummyrx[25];
+    if(tx_len >=25)
+    {
+    	SI446x_DESELECT;
+    	return;
+    }
+
+    // using transmit receive to transmit data because it actually blocks until the data is sent
+    // an additional byte is added on to the transmission so we can receive the CTS byte
+
+    HAL_StatusTypeDef res = HAL_SPI_TransmitReceive(&hspi1, data, dummyrx, tx_len+1, SI446x_TIMEOUT);
+
+    if(res != HAL_OK)
+    {
+    	SI446x_DESELECT;
+    	return;
+    }
+
+    SI446x_DESELECT;
+
+    // If checking for the ACK, perform a SPI read and see if the command was acknowledged
+    if(doack)
+    {
+		delay_cycles();
+
+		SI446x_SELECT;
+
+		int reply = 0x00;
+		uint8_t tx_requestack[2];
+		tx_requestack[0] = SI446x_CMD_READ_CMD_BUFF;
+		tx_requestack[1] = 0x00;
+
+		uint16_t attempts = 0;
+
+		// Keep trying receive until it returns 0xFF (successful ACK)
+		while (reply != 0xFF)
+		{
+			// Attempt to receive two bytes from the Si446x which should be an ACK
+			uint8_t tmprx[2] = {0,0};
+			res = HAL_SPI_TransmitReceive(&hspi1, tx_requestack, tmprx, 2, SI446x_TIMEOUT);
+			if(res != HAL_OK)
+			{
+				//error_assert_silent(ERR_VHF_SPIBUSY);
+		    	break; // Break out, deinit, and exit
+			}
+			reply = tmprx[1];
+
+			// Cycle chip select line on and off
+			if (reply != 0xFF)
+			{
+				delay_cycles();
+				SI446x_DESELECT;
+				delay_cycles();
+				SI446x_SELECT;
+				delay_cycles();
+				//HAL_GPIO_TogglePin(LED_ACT);
+			}
+
+			// Maximum number of attempts exceeded
+			if(attempts > 1024)
+			{
+				//error_assert_silent(ERR_VHF_TIMEOUT);
+				break; // Break out, deinit and exit
+			}
+			attempts++;
+		}
+    }
+
+    // Turn off activity LED
+    //HAL_GPIO_WritePin(LED_ACT, GPIO_PIN_RESET);
+
+    SI446x_DESELECT;
+    delay_cycles();
+}
+
+
+// Set transmit frequency of Si446x
+void si446x_setchannel(uint32_t frequency)
+{
+
+    // Set the output divider according to recommended ranges given in si446x datasheet
+    uint32_t outdiv = 4;
+    uint32_t band = 0;
+    if (frequency < 705000000UL) { outdiv = 6;  band = 1;};
+    if (frequency < 525000000UL) { outdiv = 8;  band = 2;};
+    if (frequency < 353000000UL) { outdiv = 12; band = 3;};
+    if (frequency < 239000000UL) { outdiv = 16; band = 4;};
+    if (frequency < 177000000UL) { outdiv = 24; band = 5;};
+
+    uint32_t f_pfd = 2 * SI446x_VCXO_FREQ / outdiv;
+
+    uint32_t n = ((uint32_t)(frequency / f_pfd)) - 1;
+
+    float ratio = (float)frequency / (float)f_pfd;
+    float rest  = ratio - (float)n;
+
+    uint32_t m = (uint32_t)(rest * 524288UL);
+
+    // Set the band parameter
+    uint32_t sy_sel = 8;
+    uint8_t set_band_property_command[] = {SI446x_CMD_SET_PROPERTY, 0x20, 0x01, 0x51, (band + sy_sel)};
+    si446x_sendcmd(5, set_band_property_command, SI446x_CHECK_ACK);
+
+    // Set the pll parameters
+    uint32_t m2 = m / 0x10000;
+    uint32_t m1 = (m - m2 * 0x10000) / 0x100;
+    uint32_t m0 = (m - m2 * 0x10000 - m1 * 0x100);
+
+    // Assemble parameter string
+    uint8_t set_frequency_property_command[] = {SI446x_CMD_SET_PROPERTY, 0x40, 0x04, 0x00, n, m2, m1, m0};
+    si446x_sendcmd(8, set_frequency_property_command, SI446x_CHECK_ACK);
+
+    // Set frequency deviation
+    // ...empirically 0xF9 looks like about 5khz. Sketchy.
+
+    //                           set prop   group     numprops  startprop   data                     // Was 0x0F 00 for ~40kHz dev, switched to 56khzish? dev
+
+    //2DF5 is correct for 56khz
+    uint8_t set_frequency_separation[] = {SI446x_CMD_SET_PROPERTY, 0x20,     0x03,      0x0a,     0x00, 0x03, 0x00};
+    si446x_sendcmd(7, set_frequency_separation, SI446x_CHECK_ACK);
+
+}
+
+
+// Turn CW transmit on
+void si446x_cw_on(void)
+{
+    // Change to TX state
+	uint8_t change_state_command[] = {SI446x_CMD_CHANGE_STATE, 0x07};
+    si446x_sendcmd(2, change_state_command, SI446x_CHECK_ACK);
+    si446x_cw_status = 1;
+}
+
+
+// Turn CW transmit off
+void si446x_cw_off(void)
+{
+    // Change to ready state
+	uint8_t change_state_command[] = {SI446x_CMD_CHANGE_STATE, 0x03};
+    si446x_sendcmd(2, change_state_command, SI446x_CHECK_ACK);
+    si446x_cw_status = 0;
+}
+
+
+// Returns 1 if CW is on or 0 if CW is off
+inline uint8_t si446x_tx_status(void)
+{
+	return si446x_cw_status;
+}
+
+
+// Initialize SPI port for generation of direct modulation for Si446x
+static void __init_spi1(void)
+{
+
+	GPIO_InitTypeDef GPIO_InitStruct;
+
+	// GPIO: VHF chip select
+	GPIO_InitStruct.Pin = SI446x_CS_PIN;
+	GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
+	GPIO_InitStruct.Pull = GPIO_NOPULL;
+	GPIO_InitStruct.Speed = GPIO_SPEED_LOW;
+	HAL_GPIO_Init(SI446x_CS_PORT, &GPIO_InitStruct);
+	SI446x_DESELECT;
+
+	// SPI pins
+	__SPI1_CLK_ENABLE();
+	GPIO_InitStruct.Pin = SI446x_SCK_PIN|SI446x_MOSI_PIN|SI446x_MOSI_PIN;
+	GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
+	GPIO_InitStruct.Pull = GPIO_NOPULL;
+	GPIO_InitStruct.Speed = GPIO_SPEED_HIGH;
+	GPIO_InitStruct.Alternate = GPIO_AF0_SPI1;
+	HAL_GPIO_Init(SI446x_SCK_PORT, &GPIO_InitStruct);
+
+	// SPI peripheral
+	hspi1.Instance = SPI1;
+	hspi1.Init.Mode = SPI_MODE_MASTER;
+
+	hspi1.Init.Direction = SPI_DIRECTION_2LINES;
+
+	hspi1.Init.DataSize = SPI_DATASIZE_8BIT;
+	hspi1.Init.CLKPolarity = SPI_POLARITY_LOW; // Double-check, this is usually high, but might be low for this chip
+	hspi1.Init.CLKPhase = SPI_PHASE_1EDGE; // was 1edge before (rising edge of clock)
+	hspi1.Init.NSS = SPI_NSS_SOFT;
+	hspi1.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_16;
+	hspi1.Init.FirstBit = SPI_FIRSTBIT_MSB;
+	hspi1.Init.TIMode = SPI_TIMODE_DISABLED;
+	hspi1.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLED;
+	hspi1.Init.NSSPMode = SPI_NSS_PULSE_DISABLED;
+	HAL_SPI_Init(&hspi1);
+}
+
+
+// Place the Si446x into shutdown
+void si446x_shutdown(void)
+{
+    HAL_GPIO_WritePin(SI446x_SHUTDOWN, GPIO_PIN_SET);
+}
+
+
+// Wake up the Si446x from shutdown
+void si446x_wakeup(void)
+{
+    HAL_GPIO_WritePin(SI446x_SHUTDOWN, GPIO_PIN_RESET);
+}
+
+
+// Accessor for SPI1  handle
+SPI_HandleTypeDef* spi1_get(void)
+{
+	return &hspi1;
+}