diff --git a/src/drivers/si4063/si4063.c b/src/drivers/si4063/si4063.c
index b4f5258..7a57bc5 100644
--- a/src/drivers/si4063/si4063.c
+++ b/src/drivers/si4063/si4063.c
@@ -100,7 +100,7 @@ static void si4063_send_command(uint8_t command, uint8_t length, uint8_t *data)
     si4063_set_chip_select(true);
 
     // Output enable time, 20ns
-    for (uint32_t i = 0; i < 0xFFFF; i++);
+    for (uint32_t i = 0; i < 0xFFFFF; i++);
 
     spi_send(command);
 
@@ -114,8 +114,8 @@ static void si4063_send_command(uint8_t command, uint8_t length, uint8_t *data)
 static void si4063_power_up()
 {
     uint8_t data[] = {
-            0x01, //
-            0x01, // No patch, boot main app. img, TXCO
+            0x01, // 0x01 = FUNC PRO - Power the chip up into EZRadio PRO functional mode.
+            0x01, // 0x01 = Reference signal is derived from an external TCXO.
             (SI4063_CLOCK >> 24) & 0xFF, // VCXO frequency
             (SI4063_CLOCK >> 16) & 0xFF,
             (SI4063_CLOCK >> 8) & 0xFF,
@@ -313,7 +313,7 @@ int32_t si4063_read_temperature_celsius_100()
     si4063_read_response(sizeof(response), response);
 
     for (int i = 0; i < sizeof(response); i++) {
-        log_info("response: %02x\n", response[i]);
+        log_info("Si4063 ADC reading: %02x\n", response[i]);
     }
 
     // Calculate the temperature in C * 10
@@ -336,7 +336,7 @@ uint8_t si4063_read_part_info()
     si4063_read_response(sizeof(response), response);
 
     for (int i = 0; i < sizeof(response); i++) {
-        log_info("part info: %02x\n", response[i]);
+        log_info("Si4063 part info: %02x\n", response[i]);
     }
 
     return response[0];
@@ -393,6 +393,7 @@ void si4063_init()
     si4603_set_shutdown(true);
     delay_us(20);
     si4603_set_shutdown(false);
+    delay_us(50);
 
     si4063_power_up();
 
diff --git a/src/hal/spi.c b/src/hal/spi.c
index 5a457bd..9a3aea6 100644
--- a/src/hal/spi.c
+++ b/src/hal/spi.c
@@ -23,7 +23,12 @@ void spi_init()
 
     // MISO
     gpio_init.GPIO_Pin = PIN_MISO;
+#ifdef RS41
     gpio_init.GPIO_Mode = GPIO_Mode_IN_FLOATING;
+#endif
+#ifdef DFM17
+    gpio_init.GPIO_Mode = GPIO_Mode_IPU;
+#endif
     gpio_init.GPIO_Speed = GPIO_Speed_50MHz;
     GPIO_Init(BANK_MISO, &gpio_init);
 
@@ -46,7 +51,8 @@ void spi_init()
     spi_init.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_256;
 #endif
 #ifdef DFM17
-    spi_init.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_32;
+    // TODO: Adjust SPI speed correctly, not sure what this should be
+    spi_init.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_64;
 #endif
     spi_init.SPI_FirstBit = SPI_FirstBit_MSB;
 #ifdef RS41
@@ -58,10 +64,18 @@ void spi_init()
 #endif
     SPI_Init(PERIPHERAL_SPI, &spi_init);
 
+#ifdef RS41
     SPI_SSOutputCmd(PERIPHERAL_SPI, ENABLE);
+#endif
+#ifdef DFM17
+    SPI_CalculateCRC(PERIPHERAL_SPI, DISABLE);
+#endif
 
     SPI_Cmd(PERIPHERAL_SPI, ENABLE);
+#ifdef RS41
+    // TODO: Why is this call even here?
     SPI_Init(PERIPHERAL_SPI, &spi_init);
+#endif
 }
 
 void spi_uninit()
@@ -84,24 +98,36 @@ void spi_uninit()
     GPIO_Init(BANK_MOSI, &gpio_init);
 }
 
-inline void spi_send(uint16_t data)
+void spi_send(uint16_t data)
 {
     // Wait for TX buffer
     while (SPI_I2S_GetFlagStatus(PERIPHERAL_SPI, SPI_I2S_FLAG_TXE) == RESET);
     SPI_I2S_SendData(PERIPHERAL_SPI, data);
+#ifdef DFM17
+    while (SPI_I2S_GetFlagStatus(PERIPHERAL_SPI, SPI_I2S_FLAG_TXE) == RESET);
+    while (SPI_I2S_GetFlagStatus(PERIPHERAL_SPI, SPI_I2S_FLAG_BSY) == SET);
+#endif
 }
 
-inline uint8_t spi_receive()
+uint8_t spi_receive()
 {
     // Wait for data in RX buffer
+#ifdef DFM17
+    while (SPI_I2S_GetFlagStatus(PERIPHERAL_SPI, SPI_I2S_FLAG_BSY) == SET);
+#endif
     while (SPI_I2S_GetFlagStatus(PERIPHERAL_SPI, SPI_I2S_FLAG_RXNE) == RESET);
     return (uint8_t) SPI_I2S_ReceiveData(PERIPHERAL_SPI);
 }
 
-inline uint8_t spi_read()
+uint8_t spi_read()
 {
-    spi_send(0xFF);
-    return spi_receive();
+    // TODO: This is the minimal read routine, not sure if reading the other registers has an effect?
+    while (SPI_I2S_GetFlagStatus(PERIPHERAL_SPI, SPI_I2S_FLAG_BSY) == SET);
+    SPI_I2S_SendData(PERIPHERAL_SPI, 0xFF);
+    while (SPI_I2S_GetFlagStatus(PERIPHERAL_SPI, SPI_I2S_FLAG_RXNE) == RESET);
+    return (uint8_t) SPI_I2S_ReceiveData(PERIPHERAL_SPI);
+    /*spi_send(0xFF);
+    return spi_receive();*/
 }
 
 void spi_set_chip_select(GPIO_TypeDef *gpio_cs, uint16_t pin_cs, bool select)
diff --git a/src/hal/system.c b/src/hal/system.c
index 5192020..02d9e01 100644
--- a/src/hal/system.c
+++ b/src/hal/system.c
@@ -305,20 +305,38 @@ void system_enable_tick()
 
 void system_set_green_led(bool enabled)
 {
+#ifdef RS41
     if (enabled) {
         GPIO_ResetBits(BANK_GREEN_LED, PIN_GREEN_LED);
     } else {
         GPIO_SetBits(BANK_GREEN_LED, PIN_GREEN_LED);
     }
+#endif
+#ifdef DFM17
+    if (enabled) {
+        GPIO_SetBits(BANK_GREEN_LED, PIN_GREEN_LED);
+    } else {
+        GPIO_ResetBits(BANK_GREEN_LED, PIN_GREEN_LED);
+    }
+#endif
 }
 
 void system_set_red_led(bool enabled)
 {
+#ifdef RS41
     if (enabled) {
         GPIO_ResetBits(BANK_RED_LED, PIN_RED_LED);
     } else {
         GPIO_SetBits(BANK_RED_LED, PIN_RED_LED);
     }
+#endif
+#ifdef DFM17
+    if (enabled) {
+        GPIO_SetBits(BANK_RED_LED, PIN_RED_LED);
+    } else {
+        GPIO_ResetBits(BANK_RED_LED, PIN_RED_LED);
+    }
+#endif
 }
 
 void system_disable_irq()