From 3d35c33cb28147d9ba51b5a822a63fee606f2d63 Mon Sep 17 00:00:00 2001
From: Hauke Petersen <hauke.petersen@fu-berlin.de>
Date: Wed, 18 Nov 2015 14:57:15 +0100
Subject: [PATCH] cpu/stm32f1: fixed i2c driver

the _stop() function now blocks until the transfer
is complete. Not waiting can lead to concurrent bus
access and subsequent to bus errors.
---
 cpu/stm32f1/periph/i2c.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/cpu/stm32f1/periph/i2c.c b/cpu/stm32f1/periph/i2c.c
index f91684766..a43dfa49f 100644
--- a/cpu/stm32f1/periph/i2c.c
+++ b/cpu/stm32f1/periph/i2c.c
@@ -451,6 +451,8 @@ static inline void _stop(I2C_TypeDef *dev)
     while (!(dev->SR1 & I2C_SR1_BTF));
     /* send STOP condition */
     dev->CR1 |= I2C_CR1_STOP;
+    /* wait until transmission is complete */
+    while (dev->SR2 & I2C_SR2_BUSY);
 }
 
 #if I2C_0_EN