diff --git a/cores/arduino/trap_handler.c b/cores/arduino/trap_handler.c
index 4b709df..bf16dbf 100644
--- a/cores/arduino/trap_handler.c
+++ b/cores/arduino/trap_handler.c
@@ -11,7 +11,7 @@ void __attribute__((weak)) wire_interrupt_handler(void)
 }
 
 // ---------------------------------------------- //
-void __attribute__((noinline, section(".ram_text"))) trap_handler(void)
+void __attribute__((noinline, section(".ram_text"), optimize("O3"))) trap_handler (void)  
 {
     // gpio interrupt
     if (EPIC_CHECK_GPIO_IRQ())
diff --git a/cores/arduino/wiring_LL.h b/cores/arduino/wiring_LL.h
index a635e5f..3649ee9 100644
--- a/cores/arduino/wiring_LL.h
+++ b/cores/arduino/wiring_LL.h
@@ -21,6 +21,10 @@
 // get ticks from systick
 #define SYSTICK_GET_TICKS()                     ((uint64_t)(SCR1_TIMER->MTIMEH)<<32 | SCR1_TIMER->MTIME)
 
+// ----------------- UART ----------------- //
+#define UART_READ_BYTE(pUart)           ((uint16_t)pUart->RXDATA)
+#define UART_IS_RX_FIFO_EMPTY(pUart)    ((pUart->FLAGS & UART_FLAGS_RXNE_M) == 0)
+
 // ----------------- TIMER16 ----------------- //
 #define TIM16_DISABLE(htim16)                   (htim16.Instance->CR &= ~TIMER16_CR_ENABLE_M)
 #define TIM16_CLEAR_INT_MASK(htim16, intMask)   (htim16.Instance->ICR = intMask)