Wire library support for TWI General Call

Squash and rebase of https://github.com/arduino/Arduino/pull/49

libraries/Wire/src/Wire.cpp

@@ -42,6 +42,7 @@ uint8_t TwoWire::txBufferLength = 0;
 uint8_t TwoWire::transmitting = 0;
 void (*TwoWire::user_onRequest)(void);
 void (*TwoWire::user_onReceive)(int);
+void (*TwoWire::user_onGcallReceive)(int);
 
 // Constructors ////////////////////////////////////////////////////////////////
 
@@ -273,12 +274,22 @@ void TwoWire::flush(void)
 }
 
 // behind the scenes function that is called when data is received
-void TwoWire::onReceiveService(uint8_t* inBytes, int numBytes)
+void TwoWire::onReceiveService(uint8_t* inBytes, int numBytes, uint8_t isGeneralCall)
 {
+  //check if general call or normal receive
+	if(isGeneralCall){
+		// don't bother if user hasn't registered a general call callback
+		if(!user_onGcallReceive){
+			return;
+		}
+	}
+	else{
 		// don't bother if user hasn't registered a callback
 		if(!user_onReceive){
 			return;
 		}
+	}
+
   // don't bother if rx buffer is in use by a master requestFrom() op
   // i know this drops data, but it allows for slight stupidity
   // meaning, they may not have read all the master requestFrom() data yet
@@ -293,8 +304,15 @@ void TwoWire::onReceiveService(uint8_t* inBytes, int numBytes)
   // set rx iterator vars
   rxBufferIndex = 0;
   rxBufferLength = numBytes;
-  // alert user program
+
+  if(isGeneralCall){
+	// alert user's general call receive callback
+	user_onGcallReceive(numBytes);
+  }
+  else{
+	// alert user's receive callback
 	user_onReceive(numBytes);
+  }
 }
 
 // behind the scenes function that is called when data is requested
@@ -312,16 +330,27 @@ void TwoWire::onRequestService(void)
   user_onRequest();
 }
 
-// sets function called on slave write
+// sets function called when slave receives data from master at slave's address
-void TwoWire::onReceive( void (*function)(int) )
+void TwoWire::onReceive( void (*recFunction)(int) )
 {
-  user_onReceive = function;
+  user_onReceive = recFunction;
 }
 
-// sets function called on slave read
+// sets function called when slave receives data from master at slaves address
-void TwoWire::onRequest( void (*function)(void) )
+// and another function called when slave receives data from a general call
+void TwoWire::onReceive( void (*recFunction)(int), void (*gcallRecFunction)(int) )
 {
-  user_onRequest = function;
+	user_onReceive = recFunction;
+	user_onGcallReceive = gcallRecFunction;
+
+	//enable general call addressing
+	twi_enableGenCall();
+}
+
+// sets function called when master requests data from slave
+void TwoWire::onRequest( void (*reqFunction)(void) )
+{
+  user_onRequest = reqFunction;
 }
 
 // Preinstantiate Objects //////////////////////////////////////////////////////

libraries/Wire/src/Wire.h

@@ -45,8 +45,9 @@ class TwoWire : public Stream
     static uint8_t transmitting;
     static void (*user_onRequest)(void);
     static void (*user_onReceive)(int);
+	static void (*user_onGcallReceive)(int);
     static void onRequestService(void);
-    static void onReceiveService(uint8_t*, int);
+    static void onReceiveService(uint8_t*, int,uint8_t);
   public:
     TwoWire();
     void begin();
@@ -70,6 +71,7 @@ class TwoWire : public Stream
     virtual int peek(void);
     virtual void flush(void);
     void onReceive( void (*)(int) );
+	void onReceive( void (*)(int), void (*)(int) );
     void onRequest( void (*)(void) );
 
     inline size_t write(unsigned long n) { return write((uint8_t)n); }

libraries/Wire/src/utility/twi.c

@@ -44,7 +44,7 @@ static volatile uint8_t twi_sendStop;			// should the transaction end with a sto
 static volatile uint8_t twi_inRepStart;			// in the middle of a repeated start
 
 static void (*twi_onSlaveTransmit)(void);
-static void (*twi_onSlaveReceive)(uint8_t*, int);
+static void (*twi_onSlaveReceive)(uint8_t*, int, uint8_t);
 
 static uint8_t twi_masterBuffer[TWI_BUFFER_LENGTH];
 static volatile uint8_t twi_masterBufferIndex;
@@ -58,6 +58,8 @@ static uint8_t twi_rxBuffer[TWI_BUFFER_LENGTH];
 static volatile uint8_t twi_rxBufferIndex;
 
 static volatile uint8_t twi_error;
+static volatile uint8_t twi_gcall_data;
+
 
 /* 
  * Function twi_init
@@ -114,8 +116,8 @@ void twi_disable(void)
  */
 void twi_setAddress(uint8_t address)
 {
-  // set twi slave address (skip over TWGCE bit)
+  // set twi slave address and leave TWGCE bit (LSB)
-  TWAR = address << 1;
+  TWAR = (address << TWA0) | ( TWAR & (1 << TWGCE) ) ;
 }
 
 /* 
@@ -134,6 +136,18 @@ void twi_setFrequency(uint32_t frequency)
   It is 72 for a 16mhz Wiring board with 100kHz TWI */
 }
 
+/*
+ * Function twi_enableGenCall
+ * Desc     enables general call address for slave
+ * Input    none
+ * Output   none
+ */
+void twi_enableGenCall(void)
+{
+  // set TWGCE bit (LSB) and leave rest of address
+  TWAR |= 1 << TWGCE;
+}
+
 /* 
  * Function twi_readFrom
  * Desc     attempts to become twi bus master and read a
@@ -328,7 +342,7 @@ uint8_t twi_transmit(const uint8_t* data, uint8_t length)
  * Input    function: callback function to use
  * Output   none
  */
-void twi_attachSlaveRxEvent( void (*function)(uint8_t*, int) )
+void twi_attachSlaveRxEvent( void (*function)(uint8_t*, int, uint8_t) )
 {
   twi_onSlaveReceive = function;
 }
@@ -481,10 +495,15 @@ ISR(TWI_vect)
       twi_state = TWI_SRX;
       // indicate that rx buffer can be overwritten and ack
       twi_rxBufferIndex = 0;
+
+	  //indicate that we have not received any gcall data
+	  twi_gcall_data = 0;
+
 	  twi_reply(1);
       break;
-    case TW_SR_DATA_ACK:       // data received, returned ack
     case TW_SR_GCALL_DATA_ACK: // data received generally, returned ack
+		  twi_gcall_data = 1; //indicate that we received some gcall data - need to send flag to receiver
+    case TW_SR_DATA_ACK:       // data received, returned ack
       // if there is still room in the rx buffer
       if(twi_rxBufferIndex < TWI_BUFFER_LENGTH){
         // put byte in buffer and ack
@@ -503,7 +522,7 @@ ISR(TWI_vect)
         twi_rxBuffer[twi_rxBufferIndex] = '\0';
       }
       // callback to user defined callback
-      twi_onSlaveReceive(twi_rxBuffer, twi_rxBufferIndex);
+      twi_onSlaveReceive(twi_rxBuffer, twi_rxBufferIndex,twi_gcall_data);
       // since we submit rx buffer to "wire" library, we can reset it
       twi_rxBufferIndex = 0;
       break;

libraries/Wire/src/utility/twi.h

@@ -41,11 +41,12 @@
   void twi_init(void);
   void twi_disable(void);
   void twi_setAddress(uint8_t);
+  void twi_enableGenCall(void);
   void twi_setFrequency(uint32_t);
   uint8_t twi_readFrom(uint8_t, uint8_t*, uint8_t, uint8_t);
   uint8_t twi_writeTo(uint8_t, uint8_t*, uint8_t, uint8_t, uint8_t);
   uint8_t twi_transmit(const uint8_t*, uint8_t);
-  void twi_attachSlaveRxEvent( void (*)(uint8_t*, int) );
+  void twi_attachSlaveRxEvent( void (*)(uint8_t*, int, uint8_t) );
   void twi_attachSlaveTxEvent( void (*)(void) );
   void twi_reply(uint8_t);
   void twi_stop(void);