diff --git a/STM32/cores/arduino/stm32/SerialUSB.cpp b/STM32/cores/arduino/stm32/SerialUSB.cpp
index b970759..fdb7e83 100644
--- a/STM32/cores/arduino/stm32/SerialUSB.cpp
+++ b/STM32/cores/arduino/stm32/SerialUSB.cpp
@@ -63,6 +63,7 @@ void SerialUSBClass::end(void){
 int SerialUSBClass::availableForWrite(void){
   //return (CDC_SERIAL_BUFFER_SIZE - available());
   //return (uint32_t)(CDC_SERIAL_BUFFER_SIZE + tx_buffer.iHead - tx_buffer.iTail) % CDC_SERIAL_BUFFER_SIZE;
+  return 0;
 }
 
 
diff --git a/STM32/cores/arduino/stm32/USBDevice.cpp b/STM32/cores/arduino/stm32/USBDevice.cpp
index 1630ae2..bab3bd9 100644
--- a/STM32/cores/arduino/stm32/USBDevice.cpp
+++ b/STM32/cores/arduino/stm32/USBDevice.cpp
@@ -84,6 +84,8 @@ bool USBDeviceClass::beginCDC() {
     USBD_CDC_RegisterInterface(&hUsbDeviceFS, &USBD_Interface_fops_FS);
 
     USBD_Start(&hUsbDeviceFS);
+
+    return true;
 }
 
 namespace Testing {
@@ -100,6 +102,8 @@ bool USBDeviceClass::beginMSC() {
     USBD_MSC_RegisterStorage(&hUsbDeviceFS, &Testing::USBD_DISK_fops);
 
     USBD_Start(&hUsbDeviceFS);
+
+    return true;
 }
 
 extern PCD_HandleTypeDef hpcd_USB_FS;
diff --git a/STM32/cores/arduino/stm32/stm32_PWM.c b/STM32/cores/arduino/stm32/stm32_PWM.c
index 1723f9f..27381d9 100644
--- a/STM32/cores/arduino/stm32/stm32_PWM.c
+++ b/STM32/cores/arduino/stm32/stm32_PWM.c
@@ -27,6 +27,8 @@ TIM_HandleTypeDef *handle;
 static uint32_t counter;
 static uint32_t period;
 
+extern void pinMode(uint8_t, uint8_t);
+
 #define min(a,b) ((a)<(b)?(a):(b))
 
 stm32_pwm_disable_callback_func stm32_pwm_disable_callback = NULL;
diff --git a/STM32/cores/arduino/stm32/stm32_gpio_af.c b/STM32/cores/arduino/stm32/stm32_gpio_af.c
index bc6526d..c2617e6 100644
--- a/STM32/cores/arduino/stm32/stm32_gpio_af.c
+++ b/STM32/cores/arduino/stm32/stm32_gpio_af.c
@@ -24,7 +24,7 @@
 
 #include CHIP_PERIPHERAL_INCLUDE
 
-GPIO_TypeDef *stm32AfGetDefault(stm32_af_pin_list_type list[], int size, const void *instance, uint32_t *pin) {
+GPIO_TypeDef *stm32AfGetDefault(const stm32_af_pin_list_type list[], int size, const void *instance, uint32_t *pin) {
     for(int i=0; i<size; i++) {
         if (instance == list[i].instance) {
             *pin = list[i].pin;
diff --git a/STM32/cores/arduino/stm32/stm32_gpio_af.h b/STM32/cores/arduino/stm32/stm32_gpio_af.h
index 81900ab..da3a597 100644
--- a/STM32/cores/arduino/stm32/stm32_gpio_af.h
+++ b/STM32/cores/arduino/stm32/stm32_gpio_af.h
@@ -140,7 +140,7 @@ void stm32AfInit(const stm32_af_pin_list_type list[], int size, const void *inst
 /**
  * Internal: get the default pin for the given peripheral
  */
-GPIO_TypeDef *stm32AfGetDefault(stm32_af_pin_list_type list[], int size, const void *instance, uint32_t *pin);
+GPIO_TypeDef *stm32AfGetDefault(const stm32_af_pin_list_type list[], int size, const void *instance, uint32_t *pin);
 
 
 #ifdef __cplusplus
diff --git a/STM32/cores/arduino/stm32/stm32_gpio_af_F1.c b/STM32/cores/arduino/stm32/stm32_gpio_af_F1.c
index 6040cf4..07aea71 100644
--- a/STM32/cores/arduino/stm32/stm32_gpio_af_F1.c
+++ b/STM32/cores/arduino/stm32/stm32_gpio_af_F1.c
@@ -24,6 +24,8 @@
 
 #include "stm32_gpio_af.h"
 
+extern void stm32GpioClock(GPIO_TypeDef *port);
+
 stm32_af_callback stm32AfGet(const stm32_af_pin_list_type list[], int size, const void *instance, const GPIO_TypeDef *port, const uint32_t pin) {
     for(int i=0; i<size; i++) {
         if (instance == list[i].instance
diff --git a/STM32/cores/arduino/stm32/stm32_gpio_exti.c b/STM32/cores/arduino/stm32/stm32_gpio_exti.c
index ca58bdb..b524ddb 100644
--- a/STM32/cores/arduino/stm32/stm32_gpio_exti.c
+++ b/STM32/cores/arduino/stm32/stm32_gpio_exti.c
@@ -50,7 +50,7 @@ void attachInterrupt(uint8_t pin, stm32_exti_callback_func callback, int mode) {
     uint8_t irq = __builtin_ffs(port_pin.pin_mask) - 1;
     callbacks[irq] = callback;
 
-    stm32GpioClock(port_pin.port);
+    stm32GpioClockEnable(port_pin.port);
 
     GPIO_InitTypeDef GPIO_InitStruct;
 
diff --git a/STM32/cores/arduino/stm32/stm32_init.c b/STM32/cores/arduino/stm32/stm32_init.c
index 7bfb713..bb58c62 100644
--- a/STM32/cores/arduino/stm32/stm32_init.c
+++ b/STM32/cores/arduino/stm32/stm32_init.c
@@ -22,6 +22,8 @@
 
 #include "stm32_def.h"
 
+extern void SystemClock_Config(void);
+
 void init() {
   HAL_Init();
   
diff --git a/STM32/cores/arduino/syscalls.c b/STM32/cores/arduino/syscalls.c
index 40999c1..cc85a83 100644
--- a/STM32/cores/arduino/syscalls.c
+++ b/STM32/cores/arduino/syscalls.c
@@ -42,9 +42,9 @@
 // Helper macro to mark unused parameters and prevent compiler warnings.
 // Appends _UNUSED to the variable name to prevent accidentally using them.
 #ifdef __GNUC__
-#define UNUSED(x) x ## _UNUSED __attribute__((__unused__))
+#define UNUSED_PARAM(x) x ## _UNUSED __attribute__((__unused__))
 #else
-#define UNUSED(x) x ## _UNUSED
+#define UNUSED_PARAM(x) x ## _UNUSED
 #endif
 
 /*----------------------------------------------------------------------------
@@ -65,20 +65,20 @@ extern int _getpid ( void ) ;
 static unsigned char *heap_brk = NULL;
 static unsigned char *heap_end = NULL;
 
-void setHeap(char *start, char *end) {
+void setHeap(unsigned char *start, unsigned char *end) {
     heap_brk = start;
     heap_end = end;
 }
 
 extern caddr_t _sbrk ( int incr )
 {
-   caddr_t *prev_heap ;
+   caddr_t prev_heap;
 
   if ( heap_brk == NULL )
   {
       heap_brk = (unsigned char *)&_end ;
   }
-  prev_heap = heap_brk;
+  prev_heap = (caddr_t)heap_brk;
 
   if (heap_end != NULL && (heap_brk + incr) > heap_end) {
       return (caddr_t)-1;
@@ -89,39 +89,39 @@ extern caddr_t _sbrk ( int incr )
   return prev_heap ;
 }
 
-extern int link( UNUSED(char *cOld), UNUSED(char *cNew) )
+extern int link( UNUSED_PARAM(char *cOld), UNUSED_PARAM(char *cNew) )
 {
   return -1 ;
 }
 
-extern int _close( UNUSED(int file) )
+extern int _close( UNUSED_PARAM(int file) )
 {
   return -1 ;
 }
 
-extern int _fstat( UNUSED(int file), struct stat *st )
+extern int _fstat( UNUSED_PARAM(int file), struct stat *st )
 {
   st->st_mode = S_IFCHR ;
 
   return 0 ;
 }
 
-extern int _isatty( UNUSED(int file) )
+extern int _isatty( UNUSED_PARAM(int file) )
 {
   return 1 ;
 }
 
-extern int _lseek( UNUSED(int file), UNUSED(int ptr), UNUSED(int dir) )
+extern int _lseek( UNUSED_PARAM(int file), UNUSED_PARAM(int ptr), UNUSED_PARAM(int dir) )
 {
   return 0 ;
 }
 
-extern int _read(UNUSED(int file), UNUSED(char *ptr), UNUSED(int len) )
+extern int _read(UNUSED_PARAM(int file), UNUSED_PARAM(char *ptr), UNUSED_PARAM(int len) )
 {
   return 0 ;
 }
 
-extern int _write( UNUSED(int file), char *ptr, int len )
+extern int _write( UNUSED_PARAM(int file), char *ptr, int len )
 {
   int iIndex = 0;
 
@@ -138,7 +138,7 @@ extern void _exit( int status )
   for ( ; ; ) ;
 }
 
-extern void _kill( UNUSED(int pid), UNUSED(int sig) )
+extern void _kill( UNUSED_PARAM(int pid), UNUSED_PARAM(int sig) )
 {
   return ;
 }
diff --git a/STM32/cores/arduino/syscalls.h b/STM32/cores/arduino/syscalls.h
index 758b0af..a3a111a 100644
--- a/STM32/cores/arduino/syscalls.h
+++ b/STM32/cores/arduino/syscalls.h
@@ -38,7 +38,7 @@
 extern "C" {
 #endif
 
-extern void setHeap(char *start, char *end);
+extern void setHeap(unsigned char *start, unsigned char *end);
 
 extern caddr_t _sbrk( int incr ) ;
 
diff --git a/STM32/libraries/SPI/src/SPI.cpp b/STM32/libraries/SPI/src/SPI.cpp
index 4495db1..ed078bf 100644
--- a/STM32/libraries/SPI/src/SPI.cpp
+++ b/STM32/libraries/SPI/src/SPI.cpp
@@ -2,6 +2,8 @@
 
 #include "variant.h"
 
+static uint8_t spi_ff_buffer = 0XFF;
+
 #if defined(MOSI) || defined(MISO) || defined(SCK)
 	SPIClass SPI(SPI1, MOSI, MISO, SCK);
 #else
diff --git a/STM32/libraries/SPI/src/SPI.h b/STM32/libraries/SPI/src/SPI.h
index 3dea083..4f2bdbd 100644
--- a/STM32/libraries/SPI/src/SPI.h
+++ b/STM32/libraries/SPI/src/SPI.h
@@ -166,8 +166,6 @@
 #ifdef STM32L4
 #endif
 
-static uint8_t spi_ff_buffer = 0XFF;
-
 class SPISettings {
   public:
     SPISettings(uint32_t clock, uint8_t bitOrder, uint8_t dataMode): clock(clock), bitOrder(bitOrder), dataMode(dataMode) {};
diff --git a/STM32/system/STM32F1/stm32_chip/stm32_STM32F103CB.h b/STM32/system/STM32F1/stm32_chip/stm32_STM32F103CB.h
index 83f5ca4..2fe322b 100644
--- a/STM32/system/STM32F1/stm32_chip/stm32_STM32F103CB.h
+++ b/STM32/system/STM32F1/stm32_chip/stm32_STM32F103CB.h
@@ -87,32 +87,32 @@ enum {
 NUM_PINS,
 };
 */
-static void AF_NO_REMAP (void) { }
-static void AF__HAL_AFIO_REMAP_CAN1_2(void) { __HAL_AFIO_REMAP_CAN1_2(); }
-static void AF__HAL_AFIO_REMAP_CAN1_3(void) { __HAL_AFIO_REMAP_CAN1_3(); }
-static void AF__HAL_AFIO_REMAP_CAN_DISABLE(void) { __HAL_AFIO_REMAP_CAN_DISABLE(); }
-static void AF__HAL_AFIO_REMAP_I2C1_DISABLE(void) { __HAL_AFIO_REMAP_I2C1_DISABLE(); }
-static void AF__HAL_AFIO_REMAP_I2C1_ENABLE(void) { __HAL_AFIO_REMAP_I2C1_ENABLE(); }
-static void AF__HAL_AFIO_REMAP_SPI1_DISABLE(void) { __HAL_AFIO_REMAP_SPI1_DISABLE(); }
-static void AF__HAL_AFIO_REMAP_SPI1_ENABLE(void) { __HAL_AFIO_REMAP_SPI1_ENABLE(); }
-static void AF__HAL_AFIO_REMAP_TIM1_DISABLE(void) { __HAL_AFIO_REMAP_TIM1_DISABLE(); }
-static void AF__HAL_AFIO_REMAP_TIM1_ENABLE(void) { __HAL_AFIO_REMAP_TIM1_ENABLE(); }
-static void AF__HAL_AFIO_REMAP_TIM1_PARTIAL(void) { __HAL_AFIO_REMAP_TIM1_PARTIAL(); }
-static void AF__HAL_AFIO_REMAP_TIM2_DISABLE(void) { __HAL_AFIO_REMAP_TIM2_DISABLE(); }
-static void AF__HAL_AFIO_REMAP_TIM2_PARTIAL_1(void) { __HAL_AFIO_REMAP_TIM2_PARTIAL_1(); }
-static void AF__HAL_AFIO_REMAP_TIM2_PARTIAL_2(void) { __HAL_AFIO_REMAP_TIM2_PARTIAL_2(); }
-static void AF__HAL_AFIO_REMAP_TIM3_DISABLE(void) { __HAL_AFIO_REMAP_TIM3_DISABLE(); }
-static void AF__HAL_AFIO_REMAP_TIM3_ENABLE(void) { __HAL_AFIO_REMAP_TIM3_ENABLE(); }
-static void AF__HAL_AFIO_REMAP_TIM3_PARTIAL(void) { __HAL_AFIO_REMAP_TIM3_PARTIAL(); }
-static void AF__HAL_AFIO_REMAP_TIM4_DISABLE(void) { __HAL_AFIO_REMAP_TIM4_DISABLE(); }
-static void AF__HAL_AFIO_REMAP_TIM4_ENABLE(void) { __HAL_AFIO_REMAP_TIM4_ENABLE(); }
-static void AF__HAL_AFIO_REMAP_USART1_DISABLE(void) { __HAL_AFIO_REMAP_USART1_DISABLE(); }
-static void AF__HAL_AFIO_REMAP_USART1_ENABLE(void) { __HAL_AFIO_REMAP_USART1_ENABLE(); }
-static void AF__HAL_AFIO_REMAP_USART2_DISABLE(void) { __HAL_AFIO_REMAP_USART2_DISABLE(); }
-static void AF__HAL_AFIO_REMAP_USART2_ENABLE(void) { __HAL_AFIO_REMAP_USART2_ENABLE(); }
-static void AF__HAL_AFIO_REMAP_USART3_DISABLE(void) { __HAL_AFIO_REMAP_USART3_DISABLE(); }
-static void AF__HAL_AFIO_REMAP_USART3_ENABLE(void) { __HAL_AFIO_REMAP_USART3_ENABLE(); }
-static void AF__HAL_AFIO_REMAP_USART3_PARTIAL(void) { __HAL_AFIO_REMAP_USART3_PARTIAL(); }
+void AF_NO_REMAP (void) { }
+void AF__HAL_AFIO_REMAP_CAN1_2(void) { __HAL_AFIO_REMAP_CAN1_2(); }
+void AF__HAL_AFIO_REMAP_CAN1_3(void) { __HAL_AFIO_REMAP_CAN1_3(); }
+//void AF__HAL_AFIO_REMAP_CAN_DISABLE(void) { __HAL_AFIO_REMAP_CAN_DISABLE(); }
+void AF__HAL_AFIO_REMAP_I2C1_DISABLE(void) { __HAL_AFIO_REMAP_I2C1_DISABLE(); }
+void AF__HAL_AFIO_REMAP_I2C1_ENABLE(void) { __HAL_AFIO_REMAP_I2C1_ENABLE(); }
+void AF__HAL_AFIO_REMAP_SPI1_DISABLE(void) { __HAL_AFIO_REMAP_SPI1_DISABLE(); }
+void AF__HAL_AFIO_REMAP_SPI1_ENABLE(void) { __HAL_AFIO_REMAP_SPI1_ENABLE(); }
+void AF__HAL_AFIO_REMAP_TIM1_DISABLE(void) { __HAL_AFIO_REMAP_TIM1_DISABLE(); }
+void AF__HAL_AFIO_REMAP_TIM1_ENABLE(void) { __HAL_AFIO_REMAP_TIM1_ENABLE(); }
+void AF__HAL_AFIO_REMAP_TIM1_PARTIAL(void) { __HAL_AFIO_REMAP_TIM1_PARTIAL(); }
+void AF__HAL_AFIO_REMAP_TIM2_DISABLE(void) { __HAL_AFIO_REMAP_TIM2_DISABLE(); }
+void AF__HAL_AFIO_REMAP_TIM2_PARTIAL_1(void) { __HAL_AFIO_REMAP_TIM2_PARTIAL_1(); }
+void AF__HAL_AFIO_REMAP_TIM2_PARTIAL_2(void) { __HAL_AFIO_REMAP_TIM2_PARTIAL_2(); }
+void AF__HAL_AFIO_REMAP_TIM3_DISABLE(void) { __HAL_AFIO_REMAP_TIM3_DISABLE(); }
+void AF__HAL_AFIO_REMAP_TIM3_ENABLE(void) { __HAL_AFIO_REMAP_TIM3_ENABLE(); }
+void AF__HAL_AFIO_REMAP_TIM3_PARTIAL(void) { __HAL_AFIO_REMAP_TIM3_PARTIAL(); }
+void AF__HAL_AFIO_REMAP_TIM4_DISABLE(void) { __HAL_AFIO_REMAP_TIM4_DISABLE(); }
+void AF__HAL_AFIO_REMAP_TIM4_ENABLE(void) { __HAL_AFIO_REMAP_TIM4_ENABLE(); }
+void AF__HAL_AFIO_REMAP_USART1_DISABLE(void) { __HAL_AFIO_REMAP_USART1_DISABLE(); }
+void AF__HAL_AFIO_REMAP_USART1_ENABLE(void) { __HAL_AFIO_REMAP_USART1_ENABLE(); }
+void AF__HAL_AFIO_REMAP_USART2_DISABLE(void) { __HAL_AFIO_REMAP_USART2_DISABLE(); }
+void AF__HAL_AFIO_REMAP_USART2_ENABLE(void) { __HAL_AFIO_REMAP_USART2_ENABLE(); }
+void AF__HAL_AFIO_REMAP_USART3_DISABLE(void) { __HAL_AFIO_REMAP_USART3_DISABLE(); }
+void AF__HAL_AFIO_REMAP_USART3_ENABLE(void) { __HAL_AFIO_REMAP_USART3_ENABLE(); }
+void AF__HAL_AFIO_REMAP_USART3_PARTIAL(void) { __HAL_AFIO_REMAP_USART3_PARTIAL(); }
 
 // --------------------ADC--------------------
 
diff --git a/STM32/variants/DISCOVERY_F746NG/variant.cpp b/STM32/variants/DISCOVERY_F746NG/variant.cpp
index beef86d..bd59fc5 100644
--- a/STM32/variants/DISCOVERY_F746NG/variant.cpp
+++ b/STM32/variants/DISCOVERY_F746NG/variant.cpp
@@ -6,7 +6,7 @@
 
 extern "C" void preinitVariant() {
     //Set heap to external SDRAM
-    setHeap((char*)0xC0000000, (char*)(0xC0000000 + 8 * 1024 * 1024));
+    setHeap((unsigned char*)0xC0000000, (unsigned char*)(0xC0000000 + 8 * 1024 * 1024));
 }
 
 extern "C" void initVariant() {