I/O expansion headers

There are four available I/O expansion headers on the XMEGA-B1 Xplained kit. Because of the low pin count on the device (LCD pins deducted), the I/O expansion header pins are shared with onboard functionality. If “clean” expansion ports are needed, cut-straps are available on some I/Os. Otherwise, it is only needed to remove a series resistor to remove onboard functionality. Following tables show what is shared on the respective header pins

Table 1. XMEGA-B1 Xplained I/O expansion header J1
Pin	J1	XMEGA pin	Shared with onboard functionality
1	TWI SDA	PC0	-
2	TWI SCL / USART XCK0	PC1	-
3	USART RXD0	PC2	-
4	USART TXD0	PC3	-
5	SPI SS	PC4	-
6	SPI MOSI / USART-SPI SCK Swap USART XCK0	PC5	Serial Flash Clock (USART-SPI SCK)
7	SPI MISO / USART-SPI MISO Swap USART RXD0	PC6	Serial Flash Clock (USART-SPI MISO)
8	SPI SCK / USART-SPI MOSI Swap USART TXD0	PC7	Serial Flash Clock (USART-SPI MISO)
9	GND	-	-
10	VCC_P3V3 (VTG)	-	-

Table 2. XMEGA-B1 Xplained I/O expansion header J2
Pin	J2	UC3 pin	Shared with onboard functionality
1	ACA0 / ADCA0 / ADCB8	PA0	-
2	ACA1 / ADCA1 / ADCB9	PA1	-
3	ACA2 / ADCA2 / ADCB10	PA2	-
4	ACA3 / ADCA3 / ADCB11	PA3	-
5	ACA4 / ADCA4 / ADCB12	PA4	-
6	ACA5 / ADCA5 / ADCB13	PA5	-
7	ACA6 / ADCA6 / ADCB14	PA6	-
8	ACA7 / ADCA7 / ADCB15	PA7	-
9	GND	-	-
10	AVCC (default = VTG)	-	-

Table 3. XMEGA-B1 Xplained I/O expansion header J3
Pin	J3	UC3 pin	Shared with onboard functionality
1	ACB0 / ADCB0 / ADCA8	PB0	NTC sensor (ADCB0)
2	ACB1 / ADCB1 / ADCA9	PB1	Potentiometer measure (ADCB1)
3	ACB2 / ADCB2 / ADCA10	PB2	LDR sensor (ADCB2)
4	ACB3 / ADCB3 / ADCA11	PB3	External Voltage measure (ADCB3)
5	ACB4 / ADCB4 / ADCA12 JTAG TMS	PB4	LED0 (PB4)
6	ACB5 / ADCB5 / ADCA13 JTAG TDI	PB5	LED1 (PB5)
7	ACB6 / ADCB6 / ADCA14 JTAG TCK	PB6	LED2 (PB6)
8	ACB7 / ADCB7 / ADCA15 JTAG TDO	PB7	LED3 (PB7)
9	GND	-	-
10	V_BUS¹	-	-

Table 4. XMEGA-B1 Xplained I/O expansion header J4
Pin	J4	UC3 pin	Shared with onboard functionality
1	TIMER OC0A / Split TIMER OC0LA	PE0	QTOUCH0 (PE0)
2	TIMER OC0B / Split TIMER OC0LB USART XCK0	PE1	QTOUCH1 (PE1)
3	TIMER OC0C / Split TIMER OC0LC USART RXD0	PE2	QTOUCH2 (PE2)
4	TIMER OC0D / Split TIMER OC0LD USART TXD0	PE3	QTOUCH3 (PE3)
5	Swap TIMER OC0A / Split TIMER OC0HA	PE4	Power LED (PE4)
6	Swap TIMER OC0B / Split TIMER OC0HB Swap USART XCK0	PE5	LCD Backlight (Swap TIMER OC0B)
7	Swap TIMER OC0C / Split TIMER OC0HC Swap USART RXD0	PE6	RTC 32.768 kHz (TOSC2 Alternate)
8	Swap TIMER OC0D / Split TIMER OC0HD Swap USART TXD0	PE7	RTC 32.768 kHz (TOSC1 Alternate )
9	GND	-	-
10	VCC_P3V3 (VTG)	-	-