Added a timeout value to the TWI_StartTransmission() function, within which the addressed device must respond.

Fixed TWI_StartTransmission() corrupting the contents of the GPIOR0 register.

LUFA/Drivers/Peripheral/AVRU4U6U7/TWI.h

@@ -56,6 +56,7 @@
 		#include <avr/io.h>
 		#include <stdbool.h>
 		#include <util/twi.h>
+		#include <util/delay.h>
 		
 	/* Enable C linkage for C++ Compilers: */
 		#if defined(__cplusplus)
@@ -131,10 +132,11 @@
 			/** Begins a master mode TWI bus communication with the given slave device address.
 			 *
 			 *  \param[in] SlaveAddress  Address of the slave TWI device to communicate with
+			 *  \param[in] TimeoutMS     Timeout period within which the slave must respond, in milliseconds
 			 *
 			 *  \return Boolean true if the device is ready for data, false otherwise
 			 */
-			bool TWI_StartTransmission(uint8_t SlaveAddress);
+			bool TWI_StartTransmission(uint8_t SlaveAddress, uint8_t TimeoutMS);
 
 	/* Disable C linkage for C++ Compilers: */
 		#if defined(__cplusplus)

LUFA/Drivers/Peripheral/TWI.c

@@ -7,18 +7,20 @@
 
 #include "TWI.h"
 
-bool TWI_StartTransmission(uint8_t SlaveAddress)
+bool TWI_StartTransmission(uint8_t SlaveAddress, uint8_t TimeoutMS)
 {
 	for (;;)
 	{
-		uint8_t IterationsRemaining = 50;
 		bool     BusCaptured = false;
+		uint16_t TimeoutRemaining;
 
-		while (IterationsRemaining-- && !BusCaptured)
-		{
 		TWCR = ((1 << TWINT) | (1 << TWSTA) | (1 << TWEN));	
-			while (!(TWCR & (1 << TWINT)));
 
+		TimeoutRemaining = (TimeoutMS * 100);
+		while (TimeoutRemaining-- && !BusCaptured)
+		{
+			if (TWCR & (1 << TWINT))
+			{
 				switch (TWSR & TW_STATUS_MASK)
 				{
 					case TW_START:
@@ -26,20 +28,37 @@ bool TWI_StartTransmission(uint8_t SlaveAddress)
 						BusCaptured = true;
 						break;
 					case TW_MT_ARB_LOST:
+						TWCR = ((1 << TWINT) | (1 << TWSTA) | (1 << TWEN));	
 						continue;
 					default:
+						TWCR = (1 << TWEN);
 						return false;
 				}
 			}
 			
+			_delay_us(10);
+		}
+		
 		if (!(BusCaptured))
+		{
+			TWCR = (1 << TWEN);
 			return false;
+		}
 		
 		TWDR = SlaveAddress;
 		TWCR = ((1 << TWINT) | (1 << TWEN));
-		while (!(TWCR & (1 << TWINT)));
 		
-		GPIOR0 = (TWSR & TW_STATUS_MASK);
+		TimeoutRemaining = (TimeoutMS * 100);
+		while (TimeoutRemaining--)
+		{
+			if (TWCR & (1 << TWINT))
+			  break;
+			  
+			_delay_us(10);
+		}
+		
+		if (!(TimeoutRemaining))
+		  return false;
 
 		switch (TWSR & TW_STATUS_MASK)
 		{

LUFA/ManPages/ChangeLog.txt

@@ -15,9 +15,11 @@
   *  - AVRISP programmer project now has a more robust timeout system, allowing for a doubling of the software USART speed
   *    for PDI and TPI programming
   *  - Increased the speed of both software and hardware TPI/PDI programming modes of the AVRISP project
+  *  - Added a timeout value to the TWI_StartTransmission() function, within which the addressed device must respond
   *
   *  <b>Fixed:</b>
   *  - Fixed software PDI/TPI programming mode in the AVRISP project not correctly toggling just the clock pin
+  *  - Fixed TWI_StartTransmission() corrupting the contents of the GPIOR0 register
   *
   *  \section Sec_ChangeLog100219 Version 100219
   *

LUFA/ManPages/MigrationInformation.txt

@@ -12,8 +12,11 @@
  *
  * \section Sec_MigrationXXXXXX Migrating from 100219 to XXXXXX
  *
+ *  <b>Non-USB Library Components</b>
+ *    - The \ref TWI_StartTransmission() function now takes in a timeout period, expressed in milliseconds, within which the addressed
+ *      device must respond or the function will abort.
+ *
  * \section Sec_Migration100219 Migrating from 091223 to 100219
- *    - (None)
  *
  *  <b>Non-USB Library Components</b>
  *    - Due to some ADC channels not being identical to their ADC MUX selection masks for single-ended conversions on some AVR models,

Projects/TemperatureDataLogger/Lib/DS1307.c

@@ -21,7 +21,7 @@ void DS1307_SetDate(uint8_t Day, uint8_t Month, uint8_t Year)
 	CurrentRTCDate.Byte3.TenYear  = (Year / 10);
 	CurrentRTCDate.Byte3.Year     = (Year % 10);
 
-	if (TWI_StartTransmission(DS1307_ADDRESS_WRITE))
+	if (TWI_StartTransmission(DS1307_ADDRESS_WRITE, 10))
 	{
 		TWI_SendByte(DS1307_DATEREG_START);
 		TWI_SendByte(CurrentRTCDate.Byte1.IntVal);
@@ -48,7 +48,7 @@ void DS1307_SetTime(uint8_t Hour, uint8_t Minute, uint8_t Second)
 	CurrentRTCTime.Byte3.Hour    = (Hour % 10);
 	CurrentRTCTime.Byte3.TwelveHourMode = false;
 	
-	if (TWI_StartTransmission(DS1307_ADDRESS_WRITE))
+	if (TWI_StartTransmission(DS1307_ADDRESS_WRITE, 10))
 	{
 		TWI_SendByte(DS1307_TIMEREG_START);
 		TWI_SendByte(CurrentRTCTime.Byte1.IntVal);
@@ -68,7 +68,7 @@ void DS1307_GetDate(uint8_t* Day, uint8_t* Month, uint8_t* Year)
 	return;
 #endif
 
-	if (TWI_StartTransmission(DS1307_ADDRESS_WRITE))
+	if (TWI_StartTransmission(DS1307_ADDRESS_WRITE, 10))
 	{
 		TWI_SendByte(DS1307_DATEREG_START);
 		
@@ -77,7 +77,7 @@ void DS1307_GetDate(uint8_t* Day, uint8_t* Month, uint8_t* Year)
 
 	DS1307_DateRegs_t CurrentRTCDate;
 
-	if (TWI_StartTransmission(DS1307_ADDRESS_READ))
+	if (TWI_StartTransmission(DS1307_ADDRESS_READ, 10))
 	{
 		TWI_ReceiveByte(&CurrentRTCDate.Byte1.IntVal, false);
 		TWI_ReceiveByte(&CurrentRTCDate.Byte2.IntVal, false);
@@ -100,7 +100,7 @@ void DS1307_GetTime(uint8_t* Hour, uint8_t* Minute, uint8_t* Second)
 	return;
 #endif
 
-	if (TWI_StartTransmission(DS1307_ADDRESS_WRITE))
+	if (TWI_StartTransmission(DS1307_ADDRESS_WRITE, 10))
 	{
 		TWI_SendByte(DS1307_TIMEREG_START);
 		
@@ -109,7 +109,7 @@ void DS1307_GetTime(uint8_t* Hour, uint8_t* Minute, uint8_t* Second)
 	
 	DS1307_TimeRegs_t CurrentRTCTime;
 
-	if (TWI_StartTransmission(DS1307_ADDRESS_READ))
+	if (TWI_StartTransmission(DS1307_ADDRESS_READ, 10))
 	{
 		TWI_ReceiveByte(&CurrentRTCTime.Byte1.IntVal, false);
 		TWI_ReceiveByte(&CurrentRTCTime.Byte2.IntVal, false);

Projects/TemperatureDataLogger/makefile

@@ -193,7 +193,7 @@ CSTANDARD = -std=gnu99
 
 # Place -D or -U options here for C sources
 CDEFS  = -DF_CPU=$(F_CPU)UL -DF_CLOCK=$(F_CLOCK)UL -DBOARD=BOARD_$(BOARD) $(LUFA_OPTS)
-CDEFS += -DDUMMY_RTC
+#CDEFS += -DDUMMY_RTC
 
 
 # Place -D or -U options here for ASM sources