diff --git a/src/RS485.cpp b/src/RS485.cpp
index ba6e80f..05bdcbb 100644
--- a/src/RS485.cpp
+++ b/src/RS485.cpp
@@ -19,6 +19,18 @@
 
 #include "RS485.h"
 
+#ifdef __MBED__
+#include "pinDefinitions.h"
+RS485Class::RS485Class(HardwareSerial& hwSerial, PinName txPin, PinName dePin, PinName rePin) :
+  _serial(&hwSerial),
+  _txPin(PinNameToIndex(txPin)),
+  _dePin(PinNameToIndex(dePin)),
+  _rePin(PinNameToIndex(rePin)),
+  _transmisionBegun(false)
+{
+}
+#endif
+
 RS485Class::RS485Class(HardwareSerial& hwSerial, int txPin, int dePin, int rePin) :
   _serial(&hwSerial),
   _txPin(txPin),
@@ -186,4 +198,8 @@ void RS485Class::setDelays(int predelay, int postdelay)
   _postdelay = postdelay;
 }
 
+#ifdef RS485_SERIAL_PORT
+RS485Class RS485(RS485_SERIAL_PORT, RS485_DEFAULT_TX_PIN, RS485_DEFAULT_DE_PIN, RS485_DEFAULT_RE_PIN);
+#else
 RS485Class RS485(SERIAL_PORT_HARDWARE, RS485_DEFAULT_TX_PIN, RS485_DEFAULT_DE_PIN, RS485_DEFAULT_RE_PIN);
+#endif
diff --git a/src/RS485.h b/src/RS485.h
index 3f9fdff..cc298b2 100644
--- a/src/RS485.h
+++ b/src/RS485.h
@@ -22,11 +22,13 @@
 
 #include <Arduino.h>
 
+#ifndef RS485_DEFAULT_TX_PIN
 #ifdef PIN_SERIAL1_TX
 #define RS485_DEFAULT_TX_PIN PIN_SERIAL1_TX
 #else
 #define RS485_DEFAULT_TX_PIN 1 
 #endif
+#endif
 
 #ifdef __AVR__
 #define RS485_DEFAULT_DE_PIN 2
@@ -35,9 +37,11 @@
 #define RS485_DEFAULT_DE_PIN A1
 #define RS485_DEFAULT_RE_PIN A0
 #else
+#ifndef RS485_DEFAULT_DE_PIN
 #define RS485_DEFAULT_DE_PIN A6
 #define RS485_DEFAULT_RE_PIN A5
 #endif
+#endif
 
 
 #define RS485_DEFAULT_PRE_DELAY 50
@@ -45,6 +49,9 @@
 
 class RS485Class : public Stream {
   public:
+#ifdef __MBED__
+    RS485Class(HardwareSerial& hwSerial, PinName txPin, PinName dePin, PinName rePin);
+#endif
     RS485Class(HardwareSerial& hwSerial, int txPin, int dePin, int rePin);
 
     virtual void begin(unsigned long baudrate);