diff --git NuttX/nuttx/arch/arm/src/stm32/stm32_i2c.c NuttX/nuttx/arch/arm/src/stm32/stm32_i2c.c
index 631ba66..669e0db 100644
--- NuttX/nuttx/arch/arm/src/stm32/stm32_i2c.c
+++ NuttX/nuttx/arch/arm/src/stm32/stm32_i2c.c
@@ -7,7 +7,7 @@
  *
  * With extensions, modifications by:
  *
- *   Copyright (C) 2011-2014, 2016 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2011-2014, 2016-2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -670,15 +670,15 @@ static inline int stm32_i2c_sem_waitdone(FAR struct stm32_i2c_priv_s *priv)
 
   do
     {
+      /* Calculate the elapsed time */
+
+      elapsed = clock_systimer() - start;
+
       /* Poll by simply calling the timer interrupt handler until it
        * reports that it is done.
        */
 
       stm32_i2c_isr(priv);
-
-      /* Calculate the elapsed time */
-
-      elapsed = clock_systimer() - start;
     }
 
   /* Loop until the transfer is complete. */
@@ -729,6 +729,10 @@ static inline void stm32_i2c_sem_waitstop(FAR struct stm32_i2c_priv_s *priv)
   start = clock_systimer();
   do
     {
+      /* Calculate the elapsed time */
+
+      elapsed = clock_systimer() - start;
+
       /* Check for STOP condition */
 
       cr1 = stm32_i2c_getreg(priv, STM32_I2C_CR1_OFFSET);
@@ -744,10 +748,6 @@ static inline void stm32_i2c_sem_waitstop(FAR struct stm32_i2c_priv_s *priv)
         {
           return;
         }
-
-      /* Calculate the elapsed time */
-
-      elapsed = clock_systimer() - start;
     }
 
   /* Loop until the stop is complete or a timeout occurs. */
diff --git NuttX/nuttx/arch/arm/src/stm32/stm32_i2c_alt.c NuttX/nuttx/arch/arm/src/stm32/stm32_i2c_alt.c
index 545a647..981edb6 100644
--- NuttX/nuttx/arch/arm/src/stm32/stm32_i2c_alt.c
+++ NuttX/nuttx/arch/arm/src/stm32/stm32_i2c_alt.c
@@ -7,7 +7,7 @@
  *
  * With extensions, modifications by:
  *
- *   Copyright (C) 2011-2014, 2016 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2011-2014, 2016-2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  *   Copyright( C) 2014 Patrizio Simona. All rights reserved.
@@ -678,15 +678,15 @@ static int stm32_i2c_sem_waitdone(FAR struct stm32_i2c_priv_s *priv)
 
   do
     {
+      /* Calculate the elapsed time */
+
+      elapsed = clock_systimer() - start;
+
       /* Poll by simply calling the timer interrupt handler until it
        * reports that it is done.
        */
 
       stm32_i2c_isr(priv);
-
-      /* Calculate the elapsed time */
-
-      elapsed = clock_systimer() - start;
     }
 
   /* Loop until the transfer is complete. */
@@ -737,6 +737,10 @@ static inline void stm32_i2c_sem_waitstop(FAR struct stm32_i2c_priv_s *priv)
   start = clock_systimer();
   do
     {
+      /* Calculate the elapsed time */
+
+      elapsed = clock_systimer() - start;
+
       /* Check for STOP condition */
 
       cr1 = stm32_i2c_getreg(priv, STM32_I2C_CR1_OFFSET);
@@ -753,9 +757,6 @@ static inline void stm32_i2c_sem_waitstop(FAR struct stm32_i2c_priv_s *priv)
           return;
         }
 
-      /* Calculate the elapsed time */
-
-      elapsed = clock_systimer() - start;
     }
 
   /* Loop until the stop is complete or a timeout occurs. */
diff --git NuttX/nuttx/arch/arm/src/stm32/stm32f30xxx_i2c.c NuttX/nuttx/arch/arm/src/stm32/stm32f30xxx_i2c.c
index 312e0b4..b2da861 100644
--- NuttX/nuttx/arch/arm/src/stm32/stm32f30xxx_i2c.c
+++ NuttX/nuttx/arch/arm/src/stm32/stm32f30xxx_i2c.c
@@ -7,7 +7,7 @@
  *
  * With extensions and modifications for the F1, F2, and F4 by:
  *
- *   Copyright (C) 2011-2013, 2016 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2011-2013, 2016-2017 Gregory Nutt. All rights reserved.
  *   Author: Gregroy Nutt <gnutt@nuttx.org>
  *
  * And this version for the STM32 F3 by
@@ -704,15 +704,15 @@ static inline int stm32_i2c_sem_waitdone(FAR struct stm32_i2c_priv_s *priv)
 
   do
     {
+      /* Calculate the elapsed time */
+
+      elapsed = clock_systimer() - start;
+
       /* Poll by simply calling the timer interrupt handler until it
        * reports that it is done.
        */
 
       stm32_i2c_isr(priv);
-
-      /* Calculate the elapsed time */
-
-      elapsed = clock_systimer() - start;
     }
 
   /* Loop until the transfer is complete. */
@@ -844,6 +844,10 @@ static inline void stm32_i2c_sem_waitstop(FAR struct stm32_i2c_priv_s *priv)
   start = clock_systimer();
   do
     {
+      /* Calculate the elapsed time */
+
+      elapsed = clock_systimer() - start;
+
       /* Check for STOP condition */
 
       cr = stm32_i2c_getreg32(priv, STM32_I2C_CR2_OFFSET);
@@ -860,9 +864,6 @@ static inline void stm32_i2c_sem_waitstop(FAR struct stm32_i2c_priv_s *priv)
           return;
         }
 
-      /* Calculate the elapsed time */
-
-      elapsed = clock_systimer() - start;
     }
 
   /* Loop until the stop is complete or a timeout occurs. */
diff --git NuttX/nuttx/arch/arm/src/stm32/stm32f40xxx_i2c.c NuttX/nuttx/arch/arm/src/stm32/stm32f40xxx_i2c.c
index 2bb715c..e91058a 100644
--- NuttX/nuttx/arch/arm/src/stm32/stm32f40xxx_i2c.c
+++ NuttX/nuttx/arch/arm/src/stm32/stm32f40xxx_i2c.c
@@ -7,7 +7,7 @@
  *
  * With extensions, modifications by:
  *
- *   Copyright (C) 2011-2014, 2016 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2011-2014, 2016-2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -672,15 +672,15 @@ static inline int stm32_i2c_sem_waitdone(FAR struct stm32_i2c_priv_s *priv)
 
   do
     {
+      /* Calculate the elapsed time */
+
+      elapsed = clock_systimer() - start;
+
       /* Poll by simply calling the timer interrupt handler until it
        * reports that it is done.
        */
 
       stm32_i2c_isr(priv);
-
-      /* Calculate the elapsed time */
-
-      elapsed = clock_systimer() - start;
     }
 
   /* Loop until the transfer is complete. */
@@ -731,6 +731,10 @@ static inline void stm32_i2c_sem_waitstop(FAR struct stm32_i2c_priv_s *priv)
   start = clock_systimer();
   do
     {
+      /* Calculate the elapsed time */
+
+      elapsed = clock_systimer() - start;
+
       /* Check for STOP condition */
 
       cr1 = stm32_i2c_getreg(priv, STM32_I2C_CR1_OFFSET);
@@ -747,9 +751,6 @@ static inline void stm32_i2c_sem_waitstop(FAR struct stm32_i2c_priv_s *priv)
           return;
         }
 
-      /* Calculate the elapsed time */
-
-      elapsed = clock_systimer() - start;
     }
 
   /* Loop until the stop is complete or a timeout occurs. */
diff --git NuttX/nuttx/arch/arm/src/stm32f7/stm32_i2c.c NuttX/nuttx/arch/arm/src/stm32f7/stm32_i2c.c
index d089db9..fd73457 100644
--- NuttX/nuttx/arch/arm/src/stm32f7/stm32_i2c.c
+++ NuttX/nuttx/arch/arm/src/stm32f7/stm32_i2c.c
@@ -7,7 +7,7 @@
  *
  * With extensions and modifications for the F1, F2, and F4 by:
  *
- *   Copyright (C) 2016 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2016-2017 Gregory Nutt. All rights reserved.
  *   Authors: Gregroy Nutt <gnutt@nuttx.org>
  *            John Wharington
  *            David Sidrane <david_s5@nscdg.com>
@@ -897,15 +897,15 @@ static inline int stm32_i2c_sem_waitdone(FAR struct stm32_i2c_priv_s *priv)
 
   do
     {
+      /* Calculate the elapsed time */
+
+      elapsed = clock_systimer() - start;
+
       /* Poll by simply calling the timer interrupt handler until it
        * reports that it is done.
        */
 
       stm32_i2c_isr(priv);
-
-      /* Calculate the elapsed time */
-
-      elapsed = clock_systimer() - start;
     }
 
   /* Loop until the transfer is complete. */
@@ -1034,6 +1034,10 @@ static inline void stm32_i2c_sem_waitstop(FAR struct stm32_i2c_priv_s *priv)
   start = clock_systimer();
   do
     {
+      /* Calculate the elapsed time */
+
+      elapsed = clock_systimer() - start;
+
       /* Check for STOP condition */
 
       cr = stm32_i2c_getreg32(priv, STM32_I2C_CR2_OFFSET);
@@ -1050,9 +1054,6 @@ static inline void stm32_i2c_sem_waitstop(FAR struct stm32_i2c_priv_s *priv)
           return;
         }
 
-      /* Calculate the elapsed time */
-
-      elapsed = clock_systimer() - start;
     }
 
   /* Loop until the stop is complete or a timeout occurs. */
diff --git NuttX/nuttx/arch/arm/src/stm32l4/stm32l4_i2c.c NuttX/nuttx/arch/arm/src/stm32l4/stm32l4_i2c.c
index eed199f..be46524 100644
--- NuttX/nuttx/arch/arm/src/stm32l4/stm32l4_i2c.c
+++ NuttX/nuttx/arch/arm/src/stm32l4/stm32l4_i2c.c
@@ -4,7 +4,7 @@
  *
  *   Copyright (C) 2011 Uros Platise. All rights reserved.
  *   Author: Uros Platise <uros.platise@isotel.eu>
- *   Copyright (C) 2011-2013, 2016 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2011-2013, 2016-2017 Gregory Nutt. All rights reserved.
  *   Author: Gregroy Nutt <gnutt@nuttx.org>
  *   Author: John Wharington
  *   Author: Sebastien Lorquet
@@ -648,15 +648,15 @@ static inline int stm32l4_i2c_sem_waitdone(FAR struct stm32l4_i2c_priv_s *priv)
 
   do
     {
+      /* Calculate the elapsed time */
+
+      elapsed = clock_systimer() - start;
+
       /* Poll by simply calling the timer interrupt handler until it
        * reports that it is done.
        */
 
       stm32l4_i2c_isr(priv);
-
-      /* Calculate the elapsed time */
-
-      elapsed = clock_systimer() - start;
     }
 
   /* Loop until the transfer is complete. */
@@ -788,6 +788,10 @@ static inline void stm32l4_i2c_sem_waitstop(FAR struct stm32l4_i2c_priv_s *priv)
   start = clock_systimer();
   do
     {
+      /* Calculate the elapsed time */
+
+      elapsed = clock_systimer() - start;
+
       /* Check for STOP condition */
 
       cr = stm32l4_i2c_getreg32(priv, STM32L4_I2C_CR2_OFFSET);
@@ -804,9 +808,6 @@ static inline void stm32l4_i2c_sem_waitstop(FAR struct stm32l4_i2c_priv_s *priv)
           return;
         }
 
-      /* Calculate the elapsed time */
-
-      elapsed = clock_systimer() - start;
     }
 
   /* Loop until the stop is complete or a timeout occurs. */