diff --git a/targets/TARGET_NUVOTON/TARGET_NUC472/device/cmsis_nvic.h b/targets/TARGET_NUVOTON/TARGET_NUC472/device/cmsis_nvic.h
index 8cb8accc79..cc87b4a4ac 100644
--- a/targets/TARGET_NUVOTON/TARGET_NUC472/device/cmsis_nvic.h
+++ b/targets/TARGET_NUVOTON/TARGET_NUC472/device/cmsis_nvic.h
@@ -24,12 +24,12 @@
 #define NVIC_NUM_VECTORS     (NVIC_USER_IRQ_OFFSET + NVIC_USER_IRQ_NUMBER)
 
 #if defined(__CC_ARM)
-#   define NVIC_RAM_VECTOR_ADDRESS  &Image$$ER_IRAMVEC$$ZI$$Base
+#   define NVIC_RAM_VECTOR_ADDRESS  ((uint32_t) &Image$$ER_IRAMVEC$$ZI$$Base)
 #elif defined(__ICCARM__)
 #   pragma section = "IRAMVEC"
 #   define NVIC_RAM_VECTOR_ADDRESS  ((uint32_t) __section_begin("IRAMVEC"))
 #elif defined(__GNUC__)
-#   define NVIC_RAM_VECTOR_ADDRESS  &__start_vector_table__
+#   define NVIC_RAM_VECTOR_ADDRESS  ((uint32_t) &__start_vector_table__)
 #endif
 
 
diff --git a/targets/TARGET_NUVOTON/TARGET_NUC472/device/startup_NUC472_442.c b/targets/TARGET_NUVOTON/TARGET_NUC472/device/startup_NUC472_442.c
index f339feafd9..4acab2847c 100644
--- a/targets/TARGET_NUVOTON/TARGET_NUC472/device/startup_NUC472_442.c
+++ b/targets/TARGET_NUVOTON/TARGET_NUC472/device/startup_NUC472_442.c
@@ -11,6 +11,14 @@
 
 #include "NUC472_442.h"
 
+/* Suppress warning messages */
+#if defined(__CC_ARM)
+// Suppress warning message: extended constant initialiser used
+#pragma diag_suppress 1296
+#elif defined(__ICCARM__)
+#elif defined(__GNUC__)
+#endif
+
 /* Macro Definitions */
 #if defined(__CC_ARM)
 #define WEAK            __attribute__ ((weak))
@@ -238,12 +246,12 @@ const uint32_t __vector_handlers[] = {
 
     /* Configure Initial Stack Pointer, using linker-generated symbols */
 #if defined(__CC_ARM)
-    &Image$$ARM_LIB_STACK$$ZI$$Limit,
+    (uint32_t) &Image$$ARM_LIB_STACK$$ZI$$Limit,
 #elif defined(__ICCARM__)
     //(uint32_t) __sfe("CSTACK"),
     (uint32_t) &CSTACK$$Limit,
 #elif defined(__GNUC__)
-    &__StackTop,
+    (uint32_t) &__StackTop,
 #endif
 
     (uint32_t) Reset_Handler,           // Reset Handler
diff --git a/targets/TARGET_NUVOTON/TARGET_NUC472/device/system_NUC472_442.c b/targets/TARGET_NUVOTON/TARGET_NUC472/device/system_NUC472_442.c
index d8af018d39..c1954ab405 100644
--- a/targets/TARGET_NUVOTON/TARGET_NUC472/device/system_NUC472_442.c
+++ b/targets/TARGET_NUVOTON/TARGET_NUC472/device/system_NUC472_442.c
@@ -58,7 +58,7 @@ void SystemCoreClockUpdate (void)            /* Get Core Clock Frequency      */
  */
 void SystemInit (void)
 {
-    uint32_t u32RTC_EN_Flag = 0;
+    //uint32_t u32RTC_EN_Flag = 0;
 
     /* FPU settings ------------------------------------------------------------*/
 #if (__FPU_PRESENT == 1) && (__FPU_USED == 1)
diff --git a/targets/TARGET_NUVOTON/TARGET_NUC472/i2c_api.c b/targets/TARGET_NUVOTON/TARGET_NUC472/i2c_api.c
index 49c32f0a5b..2bc453cc60 100644
--- a/targets/TARGET_NUVOTON/TARGET_NUC472/i2c_api.c
+++ b/targets/TARGET_NUVOTON/TARGET_NUC472/i2c_api.c
@@ -93,8 +93,8 @@ static int i2c_do_trsn(i2c_t *obj, uint32_t i2c_ctl, int sync);
 #define NU_I2C_TIMEOUT_STOP         500000
 static int i2c_poll_status_timeout(i2c_t *obj, int (*is_status)(i2c_t *obj), uint32_t timeout);
 static int i2c_poll_tran_heatbeat_timeout(i2c_t *obj, uint32_t timeout);
-static int i2c_is_stat_int(i2c_t *obj);
-static int i2c_is_stop_det(i2c_t *obj);
+//static int i2c_is_stat_int(i2c_t *obj);
+//static int i2c_is_stop_det(i2c_t *obj);
 static int i2c_is_trsn_done(i2c_t *obj);
 static int i2c_is_tran_started(i2c_t *obj);
 static int i2c_addr2data(int address, int read);
@@ -115,6 +115,8 @@ static void i2c_rollback_vector_interrupt(i2c_t *obj);
 #define TRANCTRL_STARTED        (1)
 #define TRANCTRL_NAKLASTDATA    (1 << 1)
 
+uint32_t us_ticker_read(void);
+
 void i2c_init(i2c_t *obj, PinName sda, PinName scl)
 {
     uint32_t i2c_sda = pinmap_peripheral(sda, PinMap_I2C_SDA);
@@ -178,8 +180,6 @@ void i2c_frequency(i2c_t *obj, int hz)
 
 int i2c_read(i2c_t *obj, int address, char *data, int length, int stop)
 {
-    int i;
-
     if (i2c_start(obj)) {
         i2c_stop(obj);
         return I2C_ERROR_BUS_BUSY;
@@ -203,8 +203,6 @@ int i2c_read(i2c_t *obj, int address, char *data, int length, int stop)
 
 int i2c_write(i2c_t *obj, int address, const char *data, int length, int stop)
 {
-    int i;
-    
     if (i2c_start(obj)) {
         i2c_stop(obj);
         return I2C_ERROR_BUS_BUSY;
@@ -306,7 +304,6 @@ static int i2c_addr2bspaddr(int address)
 
 static void i2c_enable_int(i2c_t *obj)
 {
-    I2C_T *i2c_base = (I2C_T *) NU_MODBASE(obj->i2c.i2c);
     const struct nu_modinit_s *modinit = get_modinit(obj->i2c.i2c, i2c_modinit_tab);
     
     core_util_critical_section_enter();
@@ -320,7 +317,6 @@ static void i2c_enable_int(i2c_t *obj)
 
 static void i2c_disable_int(i2c_t *obj)
 {
-    I2C_T *i2c_base = (I2C_T *) NU_MODBASE(obj->i2c.i2c);
     const struct nu_modinit_s *modinit = get_modinit(obj->i2c.i2c, i2c_modinit_tab);
     
     core_util_critical_section_enter();
@@ -334,7 +330,6 @@ static void i2c_disable_int(i2c_t *obj)
 
 static int i2c_set_int(i2c_t *obj, int inten)
 {
-    I2C_T *i2c_base = (I2C_T *) NU_MODBASE(obj->i2c.i2c);
     int inten_back;
     
     core_util_critical_section_enter();
@@ -374,8 +369,6 @@ int i2c_allow_powerdown(void)
 
 static int i2c_do_tran(i2c_t *obj, char *buf, int length, int read, int naklastdata)
 {
-    I2C_T *i2c_base = (I2C_T *) NU_MODBASE(obj->i2c.i2c);
-    int err = 0;
     int tran_len = 0;
     
     i2c_disable_int(obj);
@@ -386,7 +379,6 @@ static int i2c_do_tran(i2c_t *obj, char *buf, int length, int read, int naklastd
     i2c_enable_int(obj);
     
     if (i2c_poll_tran_heatbeat_timeout(obj, NU_I2C_TIMEOUT_STAT_INT)) {
-        err = I2C_ERROR_BUS_BUSY;
 #if NU_I2C_DEBUG
         MY_I2C_2 = obj->i2c;
         while (1);
@@ -502,7 +494,6 @@ static int i2c_poll_status_timeout(i2c_t *obj, int (*is_status)(i2c_t *obj), uin
 static int i2c_poll_tran_heatbeat_timeout(i2c_t *obj, uint32_t timeout)
 {
     uint32_t t1, t2, elapsed = 0;
-    I2C_T *i2c_base = (I2C_T *) NU_MODBASE(obj->i2c.i2c);
     int tran_started;
     char *tran_pos = NULL;
     char *tran_pos2 = NULL;
@@ -547,6 +538,7 @@ static int i2c_poll_tran_heatbeat_timeout(i2c_t *obj, uint32_t timeout)
     return (elapsed >= timeout);
 }
 
+#if 0
 static int i2c_is_stat_int(i2c_t *obj)
 {
     I2C_T *i2c_base = (I2C_T *) NU_MODBASE(obj->i2c.i2c);
@@ -554,12 +546,14 @@ static int i2c_is_stat_int(i2c_t *obj)
     return !! (i2c_base->CTL & I2C_CTL_SI_Msk);
 }
 
+
 static int i2c_is_stop_det(i2c_t *obj)
 {
     I2C_T *i2c_base = (I2C_T *) NU_MODBASE(obj->i2c.i2c);
 
     return ! (i2c_base->CTL & I2C_CTL_STO_Msk);
 }
+#endif
 
 static int i2c_is_trsn_done(i2c_t *obj)
 {
@@ -578,7 +572,6 @@ static int i2c_is_trsn_done(i2c_t *obj)
 
 static int i2c_is_tran_started(i2c_t *obj)
 {
-    I2C_T *i2c_base = (I2C_T *) NU_MODBASE(obj->i2c.i2c);
     int started;
     int inten_back;
     
@@ -619,7 +612,6 @@ static void i2c_irq(i2c_t *obj)
 {
     I2C_T *i2c_base = (I2C_T *) NU_MODBASE(obj->i2c.i2c);
     uint32_t status;
-    int data_recv = 0;
     
     if (I2C_GET_TIMEOUT_FLAG(i2c_base)) {
         I2C_ClearTimeoutFlag(i2c_base);
diff --git a/targets/TARGET_NUVOTON/TARGET_NUC472/spi_api.c b/targets/TARGET_NUVOTON/TARGET_NUC472/spi_api.c
index ba87ebcf43..79a3296d2b 100644
--- a/targets/TARGET_NUVOTON/TARGET_NUC472/spi_api.c
+++ b/targets/TARGET_NUVOTON/TARGET_NUC472/spi_api.c
@@ -116,7 +116,7 @@ void spi_init(spi_t *obj, PinName mosi, PinName miso, PinName sclk, PinName ssel
     // Enable IP clock
     CLK_EnableModuleClock(modinit->clkidx);
 
-    SPI_T *spi_base = (SPI_T *) NU_MODBASE(obj->spi.spi);
+    //SPI_T *spi_base = (SPI_T *) NU_MODBASE(obj->spi.spi);
     
     pinmap_pinout(mosi, PinMap_SPI_MOSI);
     pinmap_pinout(miso, PinMap_SPI_MISO);