diff --git a/Defines.h b/Defines.h
index 138451a..47e6fb5 100644
--- a/Defines.h
+++ b/Defines.h
@@ -129,9 +129,7 @@ typedef unsigned long long  ulong64_t;
 // #define SEND_RSSI_DATA
 
 // Enable for RPi 3B+, USB mode
-#if defined(STM32_USB_HOST)
 #define LONG_USB_RESET
-#endif
 
 const uint8_t BIT_MASK_TABLE[] = { 0x80U, 0x40U, 0x20U, 0x10U, 0x08U, 0x04U, 0x02U, 0x01U };
 
diff --git a/IO.h b/IO.h
index 181b4cb..d010199 100644
--- a/IO.h
+++ b/IO.h
@@ -42,17 +42,9 @@
 // ---------------------------------------------------------------------------
 
 #if defined(DUPLEX)
-#if defined(STM32_USB_HOST)
 #define CAL_DLY_LOOP 98950U
 #else
-#define CAL_DLY_LOOP 96100U
-#endif
-#else
-#if defined(STM32_USB_HOST)
 #define CAL_DLY_LOOP 110850U
-#else
-#define CAL_DLY_LOOP 104600U
-#endif
 #endif
 
 enum ADF_GAIN_MODE {
diff --git a/IOSTM.cpp b/IOSTM.cpp
index 30d9e6d..010cf06 100644
--- a/IOSTM.cpp
+++ b/IOSTM.cpp
@@ -162,11 +162,7 @@
 #define PIN_DEB              GPIO_Pin_9
 #define PORT_DEB             GPIOB
 
-#if defined(STM32_USB_HOST)
 #define PIN_NXDN_LED         GPIO_Pin_1
-#else
-#define PIN_NXDN_LED         GPIO_Pin_7
-#endif
 #define PORT_NXDN_LED        GPIOA
 
 #define PIN_DMR_LED          GPIO_Pin_13
@@ -566,8 +562,7 @@ void IO::initInt()
 
 #endif
 
-#if defined(STM32_USB_HOST)
-  // Pin PA11,PA12 = LOW, USB Reset
+    // Pin PA11,PA12 = LOW, USB Reset
     GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
     GPIO_InitStruct.GPIO_Pin = GPIO_Pin_11 | GPIO_Pin_12;
     GPIO_InitStruct.GPIO_Mode = GPIO_Mode_Out_PP;
@@ -575,8 +570,6 @@ void IO::initInt()
     GPIO_WriteBit(GPIOA, GPIO_Pin_11, Bit_RESET);
     GPIO_WriteBit(GPIOA, GPIO_Pin_12, Bit_RESET);
 
-#endif
-
 #if defined(LONG_USB_RESET)
     // 10 ms delay
     delayUS(10000U);
@@ -585,12 +578,6 @@ void IO::initInt()
     for (delay = 0; delay < 512; delay++);
 #endif
 
-#if !defined(STM32_USB_HOST)
-    GPIO_InitStruct.GPIO_Pin = GPIO_Pin_11 | GPIO_Pin_12;
-    GPIO_InitStruct.GPIO_Mode = GPIO_Mode_IN_FLOATING;
-    GPIO_Init(GPIOA, &GPIO_InitStruct);
-#endif
-
     RCC_USBCLKConfig(RCC_USBCLKSource_PLLCLK_1Div5);
     RCC_APB1PeriphClockCmd(RCC_APB1Periph_USB, ENABLE);
     NVIC_PriorityGroupConfig(NVIC_PriorityGroup_4);
diff --git a/SerialSTM.cpp b/SerialSTM.cpp
index 89fee4b..53d4f8d 100644
--- a/SerialSTM.cpp
+++ b/SerialSTM.cpp
@@ -35,14 +35,7 @@
 
 #if defined(STM32F10X_MD)
 #include <stm32f10x_flash.h>
-
-#if defined(STM32_USB_HOST)
 #include <usb_serial.h>
-#endif
-
-#if defined(STM32_USART1_HOST) && defined(STM32_USB_HOST)
-#error "You have to select STM32_USART1_HOST or STM32_USB_HOST, but not both"
-#endif
 
 // ---------------------------------------------------------------------------
 //  Constants
@@ -279,11 +272,7 @@ void SerialPort::beginInt(uint8_t n, int speed)
 {
     switch (n) {
     case 1U:
-#if defined(STM32_USART1_HOST)
-        InitUSART1(speed);
-#elif defined(STM32_USB_HOST)
         usbserial.begin();
-#endif
         break;
     case 3U:
         InitUSART2(speed);
@@ -302,11 +291,7 @@ int SerialPort::availableInt(uint8_t n)
 {
     switch (n) {
     case 1U:
-#if defined(STM32_USART1_HOST)
-        return m_USART1.available();
-#elif defined(STM32_USB_HOST)
         return usbserial.available();
-#endif
     case 3U:
         m_USART2.available();
     default:
@@ -323,12 +308,8 @@ int SerialPort::availableForWriteInt(uint8_t n)
 {
     switch (n) {
     case 1U:
-#if defined(STM32_USART1_HOST)
-        return m_USART1.availableForWrite();
-#elif defined(STM32_USB_HOST)
         //return usbserial.availableForWrite();
         return 1U; // we don't have this -- so fake it
-#endif
     case 3U:
         return m_USART2.availableForWrite();
     default:
@@ -345,11 +326,7 @@ uint8_t SerialPort::readInt(uint8_t n)
 {
     switch (n) {
     case 1U:
-#if defined(STM32_USART1_HOST)
-        return m_USART1.read();
-#elif defined(STM32_USB_HOST)
         return usbserial.read();
-#endif
     case 3U:
         return m_USART2.read();
     default:
@@ -369,15 +346,9 @@ void SerialPort::writeInt(uint8_t n, const uint8_t* data, uint16_t length, bool
 {
     switch (n) {
     case 1U:
-#if defined(STM32_USART1_HOST)
-        m_USART1.write(data, length);
-        if (flush)
-            m_USART1.flush();
-#elif defined(STM32_USB_HOST)
         usbserial.write(data, length);
         if (flush)
             usbserial.flush();
-#endif
         break;
     case 3U:
         m_USART2.write(data, length);