diff --git a/cores/arduino/UARTClass.cpp b/cores/arduino/UARTClass.cpp
index 36de1358..cd207faa 100644
--- a/cores/arduino/UARTClass.cpp
+++ b/cores/arduino/UARTClass.cpp
@@ -20,6 +20,7 @@
 #include <stdio.h>
 #include <string.h>
 #include "UARTClass.h"
+#include "Arduino.h"
 
 // Constructors ////////////////////////////////////////////////////////////////
 
@@ -31,6 +32,9 @@ UARTClass::UARTClass( Uart *pUart, IRQn_Type dwIrq, uint32_t dwId, RingBuffer *p
   _pUart=pUart;
   _dwIrq=dwIrq;
   _dwId=dwId;
+
+  _isrRx = NULL;
+  _isrTx = NULL;
 }
 
 // Public Methods //////////////////////////////////////////////////////////////
@@ -166,13 +170,47 @@ size_t UARTClass::write( const uint8_t uc_data )
   return 1;
 }
 
+void UARTClass::attachInterrupt_Receive( isrRx_t fn )
+{
+  // pause interrupts
+  uint8_t oldISR = ((__get_PRIMASK() & 0x1) == 0 && (__get_FAULTMASK() & 0x1) == 0); noInterrupts();
+  
+  // set custom function
+  _isrRx = fn;
+
+  // restore old interrupt setting
+  if (oldISR != 0) { interrupts(); }
+}
+
+void UARTClass::attachInterrupt_Send( isrTx_t fn )
+{
+  // pause interrupts
+  uint8_t oldISR = ((__get_PRIMASK() & 0x1) == 0 && (__get_FAULTMASK() & 0x1) == 0); noInterrupts();
+  
+  // set custom function for TX empty
+  _isrTx = fn;
+
+  // restore old interrupt setting
+  if (oldISR != 0) { interrupts(); }
+}
+
 void UARTClass::IrqHandler( void )
 {
   uint32_t status = _pUart->UART_SR;
 
   // Did we receive data?
-  if ((status & UART_SR_RXRDY) == UART_SR_RXRDY)
-    _rx_buffer->store_char(_pUart->UART_RHR);
+  if ((status & UART_SR_RXRDY) == UART_SR_RXRDY) {
+
+    // custom function was attached -> call it with data and status byte 
+    if (_isrRx) {
+      _isrRx(_pUart->UART_RHR, status);
+    }
+    // no custom function attached -> store data in ring buffer
+    else {
+      _rx_buffer->store_char(_pUart->UART_RHR);
+    }
+
+  }
 
   // Do we need to keep sending data?
   if ((status & UART_SR_TXRDY) == UART_SR_TXRDY) 
@@ -185,11 +223,29 @@ void UARTClass::IrqHandler( void )
     {
       // Mask off transmit interrupt so we don't get it anymore
       _pUart->UART_IDR = UART_IDR_TXRDY;
+
+      // if custom routine attached, activate TXBUFE interrupt -> delay call until transmission finished
+      if (_isrTx != NULL) {
+        _pUart->UART_IER = UART_IER_TXEMPTY;
+      }
+    }
+
+  }
+
+  // Is data transmission finished? Used for call of attached custom function at end of transmission?
+  if ((status & UART_SR_TXEMPTY) == UART_SR_TXEMPTY)
+  {
+    // Mask off interrupt so we don't get it anymore
+    _pUart->UART_IDR = UART_IDR_TXEMPTY;
+    
+    // if custom routine attached, call it
+    if (_isrTx != NULL) {
+      _isrTx();
     }
   }
 
   // Acknowledge errors
-  if ((status & UART_SR_OVRE) == UART_SR_OVRE || (status & UART_SR_FRAME) == UART_SR_FRAME)
+  if ((status & UART_SR_OVRE) == UART_SR_OVRE || (status & UART_SR_FRAME) == UART_SR_FRAME || (status & UART_SR_RXBRK) == UART_SR_RXBRK)
   {
     // TODO: error reporting outside ISR
     _pUart->UART_CR |= UART_CR_RSTSTA;
diff --git a/cores/arduino/UARTClass.h b/cores/arduino/UARTClass.h
index 3747d8be..693ee3a3 100644
--- a/cores/arduino/UARTClass.h
+++ b/cores/arduino/UARTClass.h
@@ -31,6 +31,8 @@
 #define SERIAL_8M1 UARTClass::Mode_8M1
 #define SERIAL_8S1 UARTClass::Mode_8S1
 
+// missing in CMSIS
+#define UART_SR_RXBRK (0x1u << 2)
 
 class UARTClass : public HardwareSerial
 {
@@ -60,6 +62,13 @@ class UARTClass : public HardwareSerial
 
     void IrqHandler(void);
 
+    typedef void (* isrRx_t)(uint8_t data, uint32_t status);
+    typedef void (* isrTx_t)( void );
+    void attachInterrupt_Receive( isrRx_t fn );
+    void detachInterrupt_Receive( void ) { attachInterrupt_Receive( (isrRx_t) NULL); };
+    void attachInterrupt_Send( isrTx_t fn );
+    void detachInterrupt_Send( void ) { attachInterrupt_Send( (isrTx_t) NULL); };
+
     operator bool() { return true; }; // UART always active
 
   protected:
@@ -72,6 +81,8 @@ class UARTClass : public HardwareSerial
     IRQn_Type _dwIrq;
     uint32_t _dwId;
 
+    isrRx_t  _isrRx;
+    isrTx_t  _isrTx;
 };
 
 #endif // _UART_CLASS_