Merge pull request #10 from espreng/bugfix-double-bonded-pins

Bug fix: check for activity on double bonded pins

Author: espreng

cores/arduino/wiring_analog.c

@@ -69,6 +69,11 @@ void analogReference(uint8_t mode)
 int analogRead(uint8_t pin)
 {
 	if(pin > NUM_ANALOG_INPUTS) return NOT_A_PIN;
+	
+	/* Check if TWI is operating on double bonded pin (Master Enable is high 
+		in both Master and Slave mode for bus error detection, so this can 
+		indicate an active state for Wire) */
+	if(((pin == PIN_A4) || (pin == PIN_A5)) && (TWI0.MCTRLA & TWI_ENABLE_bm)) return 0;
 
 	uint8_t low, high;
 
@@ -117,6 +122,15 @@ void analogWrite(uint8_t pin, int val)
 	uint8_t bit_pos  = digitalPinToBitPosition(pin);
 	if(bit_pos == NOT_A_PIN) return;
 
+	/* Special check for SPI_SS double bonded pin -- no action if SPI is active 
+		(Using SPI Enable bit as indicator of SPI activity) */
+	if((pin == 10) && (SPI0.CTRLA & SPI_ENABLE_bm)) return;
+	
+	/* Check if TWI is operating on double bonded pin (Master Enable is high 
+	in both Master and Slave mode for bus error detection, so this can 
+	indicate an active state for Wire) */
+	if(((pin == PIN_A4) || (pin == PIN_A5)) && (TWI0.MCTRLA & TWI_ENABLE_bm)) return;
+
 	// We need to make sure the PWM output is enabled for those pins
 	// that support it, as we turn it off when digitally reading or
 	// writing with them.  Also, make sure the pin is in output mode

cores/arduino/wiring_digital.c

@@ -31,6 +31,15 @@ void pinMode(uint8_t pin, PinMode mode)
 	uint8_t bit_pos = digitalPinToBitPosition(pin);
 
 	if ((bit_pos == NOT_A_PIN)||(mode > INPUT_PULLUP)) return;
+	
+	/* Check if TWI is operating on double bonded pin (Master Enable is high 
+	in both Master and Slave mode for bus error detection, so this can 
+	indicate an active state for Wire) */
+	if(((pin == PIN_A4) || (pin == PIN_A5)) && (TWI0.MCTRLA & TWI_ENABLE_bm)) return;
+	
+	/* Special check for SPI_SS double bonded pin -- no action if SPI is active 
+		(Using SPI Enable bit as indicator of SPI activity) */
+	if((pin == 10) && (SPI0.CTRLA & SPI_ENABLE_bm)) return;
 
 	PORT_t* port = digitalPinToPortStruct(pin);
 	if(port == NULL) return;
@@ -137,6 +146,15 @@ void digitalWrite(uint8_t pin, PinStatus val)
 	/* Get bit mask for pin */
 	uint8_t bit_mask = digitalPinToBitMask(pin);
 	if(bit_mask == NOT_A_PIN) return;
+	
+	/* Check if TWI is operating on double bonded pin (Master Enable is high 
+	in both Master and Slave mode for bus error detection, so this can 
+	indicate an active state for Wire) */
+	if(((pin == PIN_A4) || (pin == PIN_A5)) && (TWI0.MCTRLA & TWI_ENABLE_bm)) return;
+	
+	/* Special check for SPI_SS double bonded pin -- no action if SPI is active 
+		(Using SPI Enable bit as indicator of SPI activity) */
+	if((pin == 10) && (SPI0.CTRLA & SPI_ENABLE_bm)) return;
 
 	/* Turn off PWM if applicable */
 
@@ -210,6 +228,15 @@ PinStatus digitalRead(uint8_t pin)
 	/* Get bit mask and check valid pin */
 	uint8_t bit_mask = digitalPinToBitMask(pin);
 	if(bit_mask == NOT_A_PIN) return LOW;
+	
+	/* Check if TWI is operating on double bonded pin (Master Enable is high 
+	in both Master and Slave mode for bus error detection, so this can 
+	indicate an active state for Wire) */
+	if(((pin == PIN_A4) || (pin == PIN_A5)) && (TWI0.MCTRLA & TWI_ENABLE_bm)) return LOW;
+	
+	/* Special check for SPI_SS double bonded pin -- no action if SPI is active 
+		(Using SPI Enable bit as indicator of SPI activity) */
+	if((pin == 10) && (SPI0.CTRLA & SPI_ENABLE_bm)) return;
 
 	// If the pin that support PWM output, we need to turn it off
 	// before getting a digital reading.