arduino#42 Integrate solution from my https://github.com/wmarkow/Arduino/tree/issue_#1476 branch.

Author: wmarkow

Diff for: libraries/Wire/src/Wire.cpp

@@ -86,6 +86,11 @@ void TwoWire::setClock(uint32_t clock)
   twi_setFrequency(clock);
 }
 
+void TwoWire::setTimeoutInMillis(uint8_t timeout)
+{
+  twi_setTimeoutInMillis(timeout);
+}
+
 uint8_t TwoWire::requestFrom(uint8_t address, uint8_t quantity, uint32_t iaddress, uint8_t isize, uint8_t sendStop)
 {
   if (isize > 0) {

Diff for: libraries/Wire/src/Wire.h

@@ -54,6 +54,7 @@ class TwoWire : public Stream
     void begin(int);
     void end();
     void setClock(uint32_t);
+    void setTimeoutInMillis(uint8_t);
     void beginTransmission(uint8_t);
     void beginTransmission(int);
     uint8_t endTransmission(void);

Diff for: libraries/Wire/src/utility/twi.c

@@ -25,7 +25,7 @@
 #include <avr/io.h>
 #include <avr/interrupt.h>
 #include <compat/twi.h>
-#include "Arduino.h" // for digitalWrite
+#include "Arduino.h" // for digitalWrite and millis
 
 #ifndef cbi
 #define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
@@ -42,6 +42,7 @@ static volatile uint8_t twi_state;
 static volatile uint8_t twi_slarw;
 static volatile uint8_t twi_sendStop;			// should the transaction end with a stop
 static volatile uint8_t twi_inRepStart;			// in the middle of a repeated start
+static volatile uint8_t twi_timeout_ms = 0;
 
 static void (*twi_onSlaveTransmit)(void);
 static void (*twi_onSlaveReceive)(uint8_t*, int);
@@ -154,7 +155,15 @@ uint8_t twi_readFrom(uint8_t address, uint8_t* data, uint8_t length, uint8_t sen
   }
 
   // wait until twi is ready, become master receiver
+  uint32_t startMillis = millis();
   while(TWI_READY != twi_state){
+    if((twi_timeout_ms > 0) && (millis() - startMillis > twi_timeout_ms)) {
+      //timeout
+      twi_disable();
+      twi_init();
+
+      return 0;
+    }
     continue;
   }
   twi_state = TWI_MRX;
@@ -193,7 +202,15 @@ uint8_t twi_readFrom(uint8_t address, uint8_t* data, uint8_t length, uint8_t sen
     TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA) | _BV(TWINT) | _BV(TWSTA);
 
   // wait for read operation to complete
+  startMillis = millis();
   while(TWI_MRX == twi_state){
+    if((twi_timeout_ms > 0) && (millis() - startMillis > twi_timeout_ms)) {
+      //timeout
+      twi_disable();
+      twi_init();
+
+      return 0;
+    }
     continue;
   }
 
@@ -233,7 +250,15 @@ uint8_t twi_writeTo(uint8_t address, uint8_t* data, uint8_t length, uint8_t wait
   }
 
   // wait until twi is ready, become master transmitter
+  uint32_t startMillis = millis();
   while(TWI_READY != twi_state){
+    if((twi_timeout_ms > 0) && (millis() - startMillis > twi_timeout_ms)) {
+      //timeout
+      twi_disable();
+      twi_init();
+
+      return 4;
+    }
     continue;
   }
   twi_state = TWI_MTX;
@@ -275,7 +300,15 @@ uint8_t twi_writeTo(uint8_t address, uint8_t* data, uint8_t length, uint8_t wait
     TWCR = _BV(TWINT) | _BV(TWEA) | _BV(TWEN) | _BV(TWIE) | _BV(TWSTA);	// enable INTs
 
   // wait for write operation to complete
+  startMillis = millis();
   while(wait && (TWI_MTX == twi_state)){
+    if((twi_timeout_ms > 0) && (millis() - startMillis > twi_timeout_ms)) {
+      //timeout
+      twi_disable();
+      twi_init();
+
+      return 4;
+    }
     continue;
   }
 
@@ -373,7 +406,17 @@ void twi_stop(void)
 
   // wait for stop condition to be exectued on bus
   // TWINT is not set after a stop condition!
+  uint32_t counter = 0;
   while(TWCR & _BV(TWSTO)){
+    counter++;
+    if((twi_timeout_ms > 0) && (counter >= 25000)) {
+      // timeout
+      twi_disable();
+      twi_init();
+
+      return;
+    }
+
     continue;
   }
 
@@ -396,6 +439,11 @@ void twi_releaseBus(void)
   twi_state = TWI_READY;
 }
 
+void twi_setTimeoutInMillis(uint8_t timeout)
+{
+   twi_timeout_ms = timeout;
+}
+
 ISR(TWI_vect)
 {
   switch(TW_STATUS){

Diff for: libraries/Wire/src/utility/twi.h

@@ -50,6 +50,7 @@
   void twi_reply(uint8_t);
   void twi_stop(void);
   void twi_releaseBus(void);
+  void twi_setTimeoutInMillis(uint8_t);
 
 #endif