NONA4809: fix I2C pullup and prepare for A4/A5 in rev2

Author: facchinm

boards.txt

@@ -58,7 +58,7 @@ nona4809.build.board=AVR_UNO_NONA_4809
 nona4809.build.core=arduino
 nona4809.build.variant=nona4809
 nona4809.build.text_section_start=.text=0x0
-nona4809.build.extra_flags={build.328emulation} -DMILLIS_USE_TIMERB3
+nona4809.build.extra_flags={build.328emulation} -DMILLIS_USE_TIMERB3 -DNO_EXTERNAL_I2C_PULLUP
 #nona4809.build.extra_flags=-B{runtime.tools.atpack.path}/gcc/dev/{build.mcu}
 
 nona4809.bootloader.tool=avrdude

libraries/Wire/src/utility/twi.c

@@ -65,9 +65,10 @@ void TWI_MasterInit(uint32_t frequency)
 	if(twi_mode != TWI_MODE_UNKNOWN) return;
 
 	// Enable pullups just in case, should have external ones though
-	//pinMode(PIN_WIRE_SDA, INPUT_PULLUP);
-	//pinMode(PIN_WIRE_SCL, INPUT_PULLUP);
-
+#ifdef NO_EXTERNAL_I2C_PULLUP
+	pinMode(PIN_WIRE_SDA, INPUT_PULLUP);
+	pinMode(PIN_WIRE_SCL, INPUT_PULLUP);
+#endif
 	PORTMUX.TWISPIROUTEA |= TWI_MUX;
 
 	twi_mode = TWI_MODE_MASTER;

variants/nona4809/pins_arduino.h

@@ -94,8 +94,8 @@ static const uint8_t SCL = PIN_WIRE_SCL;
 #define PIN_A1   (16)
 #define PIN_A2   (15)
 #define PIN_A3   (14)
-#define PIN_A4   (20) // fixme
-#define PIN_A5   (21) // fixme
+#define PIN_A4   (26) // PF2 / AIN12
+#define PIN_A5   (27) // PF3 / AIN13
 #define PIN_A6   (18)
 #define PIN_A7   (19)