diff --git a/I2CPort.cpp b/I2CPort.cpp
index 6f366a1..03b4b9d 100644
--- a/I2CPort.cpp
+++ b/I2CPort.cpp
@@ -23,22 +23,40 @@
 #include "I2CPort.h"
 
 CI2CPort::CI2CPort(uint8_t n) :
+m_n(n),
 m_ok(false)
 {
 }
 
 bool CI2CPort::init()
 {
-  return false;
+  switch (m_n) {
+    case 1U:
+      break;
+    case 2U:
+      break;
+    case 3U:
+      break;
+    default:
+      return m_ok;
+  }
+
+  return m_ok;
 }
 
 uint8_t CI2CPort::writeCommand(const uint8_t* data, uint8_t length)
 {
+  if (!m_ok)
+    return 6U;
+
   return 6U;
 }
 
 uint8_t CI2CPort::writeData(const uint8_t* data, uint8_t length)
 {
+  if (!m_ok)
+    return 6U;
+
   return 6U;
 }
 
diff --git a/I2CPort.h b/I2CPort.h
index 01cb7d8..7ab5cfe 100644
--- a/I2CPort.h
+++ b/I2CPort.h
@@ -37,7 +37,8 @@ public:
   uint8_t writeData(const uint8_t* data, uint8_t length);
 
 private:
-  bool m_ok;
+  uint8_t m_n;
+  bool    m_ok;
 };
 
 #endif
diff --git a/STM32F4XX_Lib b/STM32F4XX_Lib
index bcd346f..18aeb6e 160000
--- a/STM32F4XX_Lib
+++ b/STM32F4XX_Lib
@@ -1 +1 @@
-Subproject commit bcd346f53036ed0eab6643d662a410861655afe2
+Subproject commit 18aeb6ea3a236088fc9f376077c651098e3a495e
diff --git a/STM32F7XX_Lib b/STM32F7XX_Lib
index 2d5f423..6241f7c 160000
--- a/STM32F7XX_Lib
+++ b/STM32F7XX_Lib
@@ -1 +1 @@
-Subproject commit 2d5f4236fa5e9828beadbc72473293f25b3ad65e
+Subproject commit 6241f7c05eeb6cf1ecd16ca0274bf310efee853f