4.1.1 Xplained Pro Extension Headers

The SAM R21 Xplained Pro headers EXT1 and EXT3 offer access to the I/O of the microcontroller in order to expand the board e.g. by connecting extensions to the board. These headers all comply with the standard Xplained Pro extension header specification. All headers have a pitch of 2.54mm.

Table 4-1. Extension Header EXT1
Pin on EXT1SAM R21 pinFunctionShared functionality
1 [ID]-Communication line to ID chip on extension board
2 [GND]-GND
3 [ADC(+)]PA06AIN[6]
4 [ADC(-)]PA07AIN[7]
5 [GPIO1]PA13GPIO
6 [GPIO2]PA28GPIO
7 [PWM(+)]PA18TCC0 / WO[2]
8 [PWM(-)]PA19TCC0 / WO[3]
9 [IRQ/GPIO]PA22EXTINT[6]
10 [SPI_SS_B/GPIO]PA23GPIO
11 [TWI_SDA]PA16SERCOM1 PAD[0] I²C SDAEXT3 and EDBG
12 [TWI_SCL]PA17SERCOM1 PAD[1] I²C SCLEXT3 and EDBG
13 [USART_RX]PA05SERCOM0 PAD[1] UART RXEDBG
14 [USART_TX]PA04SERCOM0 PAD[0] UART TXEDBG
15 [SPI_SS_A]PB03SERCOM5 PAD[1] SPI SS
16 [SPI_MOSI]PB22SERCOM5 PAD[2] SPI MOSIEXT3 and EDBG
17 [SPI_MISO]PB02SERCOM5 PAD[0] SPI MISOEXT3 and EDBG
18 [SPI_SCK]PB23SERCOM5 PAD[3] SPI SCKEXT3 and EDBG
19 [GND]-GND
20 [VCC]-VCC
Table 4-2. Extension Header EXT3
Pin on EXT3SAM R21 pinFunctionShared functionality
1 [ID]-Communication line to ID chip on extension board
2 [GND]-GND
3 [ADC(+)]--
4 [ADC(-)]--
5 [GPIO1]PA15GPIO
6 [GPIO2]-
7 [PWM(+)]-
8 [PWM(-)]-
9 [IRQ/GPIO]-
10 [SPI_SS_B/GPIO]PA08GPIOEDBG
11 [TWI_SDA]PA16SERCOM1 PAD[0] I²C SDAEXT1 and EDBG
12 [TWI_SCL]PA17SERCOM1 PAD[1] I²C SCLEXT1 and EDBG
13 [USART_RX]--
14 [USART_TX]--
15 [SPI_SS_A]PA14GPIOEDBG
16 [SPI_MOSI]PB22SERCOM5 PAD[2] SPI MOSIEXT1 and EDBG
17 [SPI_MISO]PB02SERCOM5 PAD[0] SPI MISOEXT1 and EDBG
18 [SPI_SCK]PB23SERCOM5 PAD[3] SPI SCKEXT1 and EDBG
19 [GND]-GND
20 [VCC]-VCC