diff --git a/CHANGELOG.md b/CHANGELOG.md
index 598ffc7..5f759ee 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,13 +6,19 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
 
+## [1.7.3] - 2023-05-10
+- fix #55 ==> redo fix #53
+  - add test to detect **MBED** and **RP2040**
+- adjust **I2C_BUFFERSIZE** for RP2040 to 128.
+- update readme.md
+
+
 ## [1.7.2] - 2023-05-02
 - fix #53 support RP2040 (kudos to jotamachuca)
 - move code from .h to .cpp
 - make I2C_WRITEDELAY overridable
 - minor edits
 
-
 ## [1.7.1] - 2023-01-12
 - add setDeviceSize()
 - add setPageSize()
@@ -26,6 +32,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ## [1.7.0] - 2022-12-02
 - fix #48 rewrote constructor.
 
+----
+
 ## [1.6.2] - 2022-10-30
 - Add RP2040 support to build-CI.
 - Add CHANGELOG.md
diff --git a/I2C_eeprom.cpp b/I2C_eeprom.cpp
index 4371b2d..985231f 100644
--- a/I2C_eeprom.cpp
+++ b/I2C_eeprom.cpp
@@ -1,7 +1,7 @@
 //
 //    FILE: I2C_eeprom.cpp
 //  AUTHOR: Rob Tillaart
-// VERSION: 1.7.2
+// VERSION: 1.7.3
 // PURPOSE: Arduino Library for external I2C EEPROM 24LC256 et al.
 //     URL: https://github.com/RobTillaart/I2C_EEPROM.git
 
@@ -24,7 +24,7 @@
 
 //  I2C buffer needs max 2 bytes for EEPROM address
 //  1 byte for EEPROM register address is available in transmit buffer
-#if defined(ESP32) || defined(ESP8266)
+#if defined(ESP32) || defined(ESP8266) || defined(PICO_RP2040)
 #define I2C_BUFFERSIZE           128
 #else
 #define I2C_BUFFERSIZE           30   //  AVR, STM
@@ -43,17 +43,18 @@ I2C_eeprom::I2C_eeprom(const uint8_t deviceAddress, TwoWire * wire) :
 
 I2C_eeprom::I2C_eeprom(const uint8_t deviceAddress, const uint32_t deviceSize, TwoWire * wire)
 {
-    _deviceAddress = deviceAddress;
-    _deviceSize = setDeviceSize(deviceSize);
-    _pageSize = getPageSize(_deviceSize);
-    _wire = wire;
+  _deviceAddress = deviceAddress;
+  _deviceSize = setDeviceSize(deviceSize);
+  _pageSize = getPageSize(_deviceSize);
+  _wire = wire;
 
-    //  Chips 16 Kbit (2048 Bytes) or smaller only have one-word addresses.
-    this->_isAddressSizeTwoWords = deviceSize > I2C_DEVICESIZE_24LC16;
+  //  Chips 16 Kbit (2048 Bytes) or smaller only have one-word addresses.
+  this->_isAddressSizeTwoWords = deviceSize > I2C_DEVICESIZE_24LC16;
 }
 
 
 #if defined(ESP8266) || defined(ESP32)
+
 bool I2C_eeprom::begin(uint8_t sda, uint8_t scl)
 {
    //  if (_wire == 0) Serial.println("zero");  //  test #48
@@ -68,10 +69,9 @@ bool I2C_eeprom::begin(uint8_t sda, uint8_t scl)
   _lastWrite = 0;
   return isConnected();
 }
-#endif
 
+#elif defined(ARDUINO_ARCH_RP2040) && !defined(__MBED__)
 
-#if defined(PICO_RP2040)
 bool I2C_eeprom::begin(uint8_t sda, uint8_t scl)
 {
   if ((sda < 255) && (scl < 255))
@@ -83,6 +83,7 @@ bool I2C_eeprom::begin(uint8_t sda, uint8_t scl)
   _lastWrite = 0;
   return isConnected();
 }
+
 #endif
 
 
diff --git a/I2C_eeprom.h b/I2C_eeprom.h
index 78fdec7..bb79432 100644
--- a/I2C_eeprom.h
+++ b/I2C_eeprom.h
@@ -2,7 +2,7 @@
 //
 //    FILE: I2C_eeprom.h
 //  AUTHOR: Rob Tillaart
-// VERSION: 1.7.2
+// VERSION: 1.7.3
 // PURPOSE: Arduino Library for external I2C EEPROM 24LC256 et al.
 //     URL: https://github.com/RobTillaart/I2C_EEPROM.git
 
@@ -11,7 +11,7 @@
 #include "Wire.h"
 
 
-#define I2C_EEPROM_VERSION          (F("1.7.2"))
+#define I2C_EEPROM_VERSION          (F("1.7.3"))
 
 
 #define I2C_DEVICESIZE_24LC512      65536
@@ -59,7 +59,9 @@ public:
     */
   I2C_eeprom(const uint8_t deviceAddress, const uint32_t deviceSize, TwoWire *wire = &Wire);
 
-#if defined(ESP8266) || defined(ESP32) || defined(PICO_RP2040)
+
+//  MBED test ==> see #55, #53
+#if defined(ESP8266) || defined(ESP32) || (defined(ARDUINO_ARCH_RP2040) && !defined(__MBED__))
   //  set the I2C pins explicitly (overrule)
   bool     begin(uint8_t sda, uint8_t scl);
 #endif
diff --git a/README.md b/README.md
index 6361cc4..b3ff6c2 100644
--- a/README.md
+++ b/README.md
@@ -20,6 +20,16 @@ MicroChip 24LC512, 24LC256, 24LC64, 24LC32, 24LC16, 24LC08, 24LC04, 24LC02, 24LC
 The **I2C_eeprom_cyclic_store** interface is documented [here](README_cyclic_store.md)
 
 
+#### RP2040
+
+There are at least two boards modules for the RP2040 that use a different Wire libraries. 
+One from "Earle F. Philhower" and an "MBED" one. See issues #53 and #55 for details.
+
+In 1.7.3 defines are checked to select between these two and as far as tested this seems
+to solve the issue #53 while being backwards compatible.
+If a better solution is found, it will be implemented. 
+
+
 #### Links
 
 - https://github.com/RobTillaart/I2C_24LC1025
diff --git a/library.json b/library.json
index 9d57281..9a85306 100644
--- a/library.json
+++ b/library.json
@@ -15,7 +15,7 @@
     "type": "git",
     "url": "https://github.com/RobTillaart/I2C_EEPROM.git"
   },
-  "version": "1.7.2",
+  "version": "1.7.3",
   "license": "MIT",
   "frameworks": "arduino",
   "platforms": "*",
diff --git a/library.properties b/library.properties
index 4139f64..45c9250 100644
--- a/library.properties
+++ b/library.properties
@@ -1,5 +1,5 @@
 name=I2C_EEPROM
-version=1.7.2
+version=1.7.3
 author=Rob Tillaart <rob.tillaart@gmail.com>
 maintainer=Rob Tillaart <rob.tillaart@gmail.com>
 sentence=Library for I2C EEPROMS