Add Wire timeout

Enable Wire timeout py adding -DWIRE_TIMEOUT as a compiler flag, or by incommening a line in Wire_timeout.h

Author: MCUdude

avr/libraries/Wire/keywords.txt

@@ -17,6 +17,9 @@ endTransmission	KEYWORD2
 requestFrom	KEYWORD2
 onReceive	KEYWORD2
 onRequest	KEYWORD2
+setWireTimeout	KEYWORD2
+getWireTimeoutFlag	KEYWORD2
+clearWireTimeoutFlag	KEYWORD2
 
 #######################################
 # Instances (KEYWORD2)

avr/libraries/Wire/library.properties

@@ -1,5 +1,5 @@
 name=Wire
-version=1.0
+version=1.1
 author=Arduino
 maintainer=MCUdude
 sentence=Allows the communication between devices or sensors connected via Two Wire Interface Bus.

avr/libraries/Wire/src/Wire.cpp

@@ -1,5 +1,5 @@
 /*
-  TwoWire.cpp - TWI/I2C library for Wiring & Arduino
+  Wire.cpp - TWI/I2C library for Wiring & Arduino
   Copyright (c) 2006 Nicholas Zambetti.  All right reserved.
 
   This library is free software; you can redistribute it and/or
@@ -19,6 +19,7 @@
   Modified 2012 by Todd Krein (todd@krein.org) to implement repeated starts
   Modified 2017 by Chuck Todd (ctodd@cableone.net) to correct Unconfigured Slave Mode reboot
   Modified 2020 by Asuki Kono (asukiaaa@gmail.com) to use TwoWire class for Wire1
+  Modified 2020 by Greyson Christoforo (grey@christoforo.net) to implement timeouts
 */
 
 extern "C" {
@@ -122,6 +123,54 @@ uint8_t TwoWire::requestFrom(uint8_t address, uint8_t quantity, uint32_t iaddres
   return read;
 }
 
+#if defined(WIRE_TIMEOUT)
+/**
+ * Sets the TWI timeout.
+ *
+ * This limits the maximum time to wait for the TWI hardware. If more time passes, the bus is assumed
+ * to have locked up (e.g. due to noise-induced glitches or faulty slaves) and the transaction is aborted.
+ * Optionally, the TWI hardware is also reset, which can be required to allow subsequent transactions to
+ * succeed in some cases (in particular when noise has made the TWI hardware think there is a second
+ * master that has claimed the bus).
+ *
+ * When a timeout is triggered, a flag is set that can be queried with `getWireTimeoutFlag()` and is cleared
+ * when `clearWireTimeoutFlag()` or `setWireTimeoutUs()` is called.
+ *
+ * Note that this timeout can also trigger while waiting for clock stretching or waiting for a second master
+ * to complete its transaction. So make sure to adapt the timeout to accomodate for those cases if needed.
+ * A typical timeout would be 25ms (which is the maximum clock stretching allowed by the SMBus protocol),
+ * but (much) shorter values will usually also work.
+ *
+ * In the future, a timeout will be enabled by default, so if you require the timeout to be disabled, it is
+ * recommended you disable it by default using `setWireTimeoutUs(0)`, even though that is currently
+ * the default.
+ *
+ * @param timeout a timeout value in microseconds, if zero then timeout checking is disabled
+ * @param reset_with_timeout if true then TWI interface will be automatically reset on timeout
+ *                           if false then TWI interface will not be reset on timeout
+
+ */
+void TwoWire::setWireTimeout(uint32_t timeout, bool reset_with_timeout){
+  twi_setTimeoutInMicros(timeout, reset_with_timeout);
+}
+
+/**
+ * Returns the TWI timeout flag.
+ *
+ * @return true if timeout has occured since the flag was last cleared.
+ */
+bool TwoWire::getWireTimeoutFlag(void){
+  return(twi_manageTimeoutFlag(false));
+}
+
+/**
+ * Clears the TWI timeout flag.
+ */
+void TwoWire::clearWireTimeoutFlag(void){
+  twi_manageTimeoutFlag(true);
+}
+#endif // WIRE_TIMEOUT
+
 uint8_t TwoWire::requestFrom(uint8_t address, uint8_t quantity, uint8_t sendStop) {
   return requestFrom((uint8_t)address, (uint8_t)quantity, (uint32_t)0, (uint8_t)0, (uint8_t)sendStop);
 }
@@ -161,8 +210,8 @@ void TwoWire::beginTransmission(int address)
 //  Originally, 'endTransmission' was an f(void) function.
 //  It has been modified to take one parameter indicating
 //  whether or not a STOP should be performed on the bus.
-//  Calling endTransmission(false) allows a sketch to 
-//  perform a repeated start. 
+//  Calling endTransmission(false) allows a sketch to
+//  perform a repeated start.
 //
 //  WARNING: Nothing in the library keeps track of whether
 //  the bus tenure has been properly ended with a STOP. It

avr/libraries/Wire/src/Wire.h

@@ -26,6 +26,7 @@
 #include <Arduino.h>
 #include <inttypes.h>
 #include "Stream.h"
+#include "Wire_timeout.h"
 
 
 // WIRE_HAS_END means Wire has end()
@@ -57,6 +58,11 @@ class TwoWire : public Stream
     void begin(int);
     void end();
     void setClock(uint32_t);
+    #if defined(WIRE_TIMEOUT)
+      void setWireTimeout(uint32_t timeout = 25000, bool reset_with_timeout = false);
+      bool getWireTimeoutFlag(void);
+      void clearWireTimeoutFlag(void);
+    #endif
     void beginTransmission(uint8_t);
     void beginTransmission(int);
     uint8_t endTransmission(void);

avr/libraries/Wire/src/Wire_timeout.h

@@ -0,0 +1,4 @@
+// Enable Wire timeout by uncommenting the line below
+#ifndef WIRE_TIMEOUT
+#define WIRE_TIMEOUT
+#endif