Various fixes. Changed stm32.h to remove compile warnings. Changed Wire files to make Wire compile with I2CDev by addition of BUFFER_LENGTH definition, and fixed issue that prevented I2CScanner from working, - by changes in WireBase.cpp, Wire.cpp. Also fixed issue with SCL and SDA pin assignments being the reverse of hardware I2C - to enable future upgrades to Hardware I2C on the same pins, i.e PB6 and PB6 I2C channel 1

STM32F1XX/libraries/Wire/Wire.cpp

@@ -36,6 +36,10 @@
  * Code was derived from the original Wire for maple code by leaflabs and the
  * modifications by gke and ala42.
  */
+ /*
+  * Updated by Roger Clark. 20141111. Fixed issue when process() returned because of missing ACK (often caused by invalid device address being used), caused SCL to be left
+  * LOW so that in the next call to process() , the first clock pulse was not sent, because SCL was LOW when it should have been high.
+  */
 
 #include "Wire.h"
 
@@ -127,16 +131,21 @@ uint8 TwoWire::process() {
     i2c_start();
     // shift out the address we're transmitting to
     i2c_shift_out(sla_addr);
-    if (!i2c_get_ack()) {
+    if (!i2c_get_ack()) 
+	{
+		set_scl(HIGH);// Roger Clark. 20141110 added to set clock high again, as it will be left in a low state otherwise
         return ENACKADDR;
     }
     // Recieving
     if (itc_msg.flags == I2C_MSG_READ) {
         while (itc_msg.xferred < itc_msg.length) {
             itc_msg.data[itc_msg.xferred++] = i2c_shift_in();
-            if (itc_msg.xferred < itc_msg.length) {
+            if (itc_msg.xferred < itc_msg.length) 
+			{
                 i2c_send_ack();
-            } else {
+            } 
+			else 
+			{
                 i2c_send_nack();
             }
         }
@@ -145,7 +154,9 @@ uint8 TwoWire::process() {
     else {
         for (uint8 i = 0; i < itc_msg.length; i++) {
             i2c_shift_out(itc_msg.data[i]);
-            if (!i2c_get_ack()) {
+            if (!i2c_get_ack()) 
+			{
+				set_scl(HIGH);// Roger Clark. 20141110 added to set clock high again, as it will be left in a low state otherwise
                 return ENACKTRNS;
             }
             itc_msg.xferred++;
@@ -180,4 +191,4 @@ TwoWire::~TwoWire() {
 
 // Declare the instance that the users of the library can use
 //TwoWire Wire(SCL, SDA, SOFT_STANDARD);
-TwoWire Wire(PB7, PB6, SOFT_FAST);
+TwoWire Wire(PB6, PB7, SOFT_FAST);

STM32F1XX/libraries/Wire/Wire.h

@@ -57,6 +57,7 @@
 //#define I2C_DELAY(x) {uint32 time=micros(); while(time>(micros()+x));}
 #define I2C_DELAY(x) do{for(int i=0;i<x;i++) {asm volatile("nop");}}while(0)
 
+#define BUFFER_LENGTH 32
 
 
 class TwoWire : public WireBase {

STM32F1XX/libraries/Wire/WireBase.cpp

@@ -60,13 +60,15 @@ void WireBase::beginTransmission(int slave_address) {
 }
 
 uint8 WireBase::endTransmission(void) {
+    uint8 retVal;
+	
 	if (tx_buf_overflow) {
         return EDATA;
     }
-    process();
+    retVal=process();// Changed so that the return value from process is returned by this function see also the return line below
     tx_buf_idx = 0;
     tx_buf_overflow = false;
-    return SUCCESS;
+    return retVal;//SUCCESS;
 }
 
 //TODO: Add the ability to queue messages (adding a boolean to end of function

STM32F1XX/system/libmaple/stm32f1/include/series/stm32.h

@@ -28,6 +28,10 @@
  * @file libmaple/stm32f1/include/series/stm32.h
  * @brief STM32F1 chip- and series-specific definitions.
  */
+ /*
+  * Modified by Roger Clark. 20141111. Wrapped #define STM32_MEDIUM_DENSITY in #ifndef 
+  * to prevent redefinition warnings as SSTM32_MEDIUM_DENSITY is defined in boards.txt as a compilor define.
+  */
 
 #ifndef _LIBMAPLE_STM32F1_H_
 #define _LIBMAPLE_STM32F1_H_
@@ -68,7 +72,9 @@ extern "C" {
 #   define STM32_F1_LINE                STM32_F1_LINE_PERFORMANCE
 #   define STM32_NR_GPIO_PORTS          4
 #   define STM32_SRAM_END               ((void*)0x20005000)
+#ifndef STM32_MEDIUM_DENSITY
 #   define STM32_MEDIUM_DENSITY
+#endif
 
 #elif defined(MCU_STM32F103ZE)
 #   define STM32_F1_LINE                STM32_F1_LINE_PERFORMANCE
@@ -83,13 +89,17 @@ extern "C" {
      * so we'll live with this for now. */
 #   define STM32_NR_GPIO_PORTS          3
 #   define STM32_SRAM_END               ((void*)0x20005000)
+#ifndef STM32_MEDIUM_DENSITY
 #   define STM32_MEDIUM_DENSITY
+#endif
 
 #elif defined(MCU_STM32F103RE)
 #   define STM32_F1_LINE                STM32_F1_LINE_PERFORMANCE
 #   define STM32_NR_GPIO_PORTS          4
 #   define STM32_SRAM_END               ((void*)0x20010000)
-#   define STM32_HIGH_DENSITY
+#ifndef STM32_MEDIUM_DENSITY
+#   define STM32_MEDIUM_DENSITY
+#endif
 
 #elif defined(MCU_STM32F100RB)
 #   define STM32_F1_LINE                STM32_F1_LINE_VALUE
@@ -103,7 +113,9 @@ extern "C" {
 #   define STM32_SRAM_END               ((void*)0x20005000)
 #   define NR_GPIO_PORTS                STM32_NR_GPIO_PORTS
 #   define STM32_F1_LINE                STM32_F1_LINE_PERFORMANCE
+#ifndef STM32_MEDIUM_DENSITY
 #   define STM32_MEDIUM_DENSITY
+#endif
 
 #else
 #warning "Unsupported or unspecified STM32F1 MCU."