4.1.1 Xplained Pro Extension Headers

The SAM L21 Xplained Pro headers EXT1, EXT2, and EXT3 offers access to the I/O of the microcontroller in order to expand the board e.g., by connecting extensions to the board. These headers are based on the standard extension header specified in Table 3-4. The headers have a pitch of 2.54mm.

Table 4-1. Extension Header EXT1
EXT1 pinSAM L21 pinFunctionShared functionality
1 [ID]--Communication line to the ID chip on an extension board
2 [GND]--Ground
3 [ADC(+)]PB05AIN[13]
4 [ADC(-)]PA03AIN[1]
5 [GPIO1]PB06GPIO
6 [GPIO2]PB07GPIO
7 [PWM(+)]PA12TCC2/WO[0]
8 [PWM(-)]PA13TCC2/WO[1]
9 [IRQ/GPIO]PB04IRQ4/GPIO
10 [SPI_SS_B/GPIO]PA02GPIOSW0
11 [TWI_SDA]PA08SERCOM2 PAD[0] I²C SDAEXT2, EXT3, and EDBG I²C
12 [TWI_SCL]PA09SERCOM2 PAD[1] I²C SCLEXT2, EXT3, and EDBG I²C
13 [USART_RX]PB09SERCOM4 PAD[1] UART RX
14 [USART_TX]PB08SERCOM4 PAD[0] UART TX
15 [SPI_SS_A]PA05SERCOM0 PAD[1] SPI SS
16 [SPI_MOSI]PA06SERCOM0 PAD[2] SPI MOSI
17 [SPI_MISO]PA04SERCOM0 PAD[0] SPI MISO
18 [SPI_SCK]PA07SERCOM0 PAD[3] SPI SCK
19 [GND]--Ground
20 [VCC]--Power for extension board
Table 4-2. Extension Header EXT2
EXT2 pinSAM L21 pinFunctionShared functionality
1 [ID]--Communication line to the ID chip on an extension board
2 [GND]--Ground
3 [ADC(+)]PA10AIN[18] / PTC_Y8Onboard QTouch Button 1
4 [ADC(-)]PA11AIN[19]
5 [GPIO1]PA20GPIOEDBG GPIO2
6 [GPIO2]PA21GPIOEDBG GPIO3
7 [PWM(+)]PB12TC4/WO[0]
8 [PWM(-)]PB13TC4/WO[1]
9 [IRQ/GPIO]PB14IRQ14/GPIO
10 [SPI_SS_B/GPIO]PB15GPIO
11 [TWI_SDA]PA08SERCOM2 PAD[0] I²C SDAEXT1, EXT3, and EDBG I²C
12 [TWI_SCL]PA09SERCOM2 PAD[1] I²C SCLEXT1, EXT3, and EDBG I²C
13 [USART_RX]PA19SERCOM1 PAD[3] UART RXEXT3 UART
14 [USART_TX]PA18SERCOM1 PAD[2] UART TXEXT3 UART
15 [SPI_SS_A]PA17GPIO
16 [SPI_MOSI]PB22SERCOM5 PAD[2] SPI MOSIEXT3 and EDBG SPI
17 [SPI_MISO]PB16SERCOM5 PAD[0] SPI MISOEXT3 and EDBG SPI
18 [SPI_SCK]PB23SERCOM5 PAD[3] SPI SCKEXT3 and EDBG SPI
19 [GND]--Ground
20 [VCC]--Power for extension board
Table 4-3. Extension Header EXT3
EXT3 pinSAM L21 pinFunctionShared functionality
1 [ID]--Communication line to the ID chip on an extension board
2 [GND]--Ground
3 [ADC(+)]PB00AIN[8]
4 [ADC(-)]PB01AIN[9]EDBG GPIO0
5 [GPIO1]PB30GPIO
6 [GPIO2]PA15GPIO
7 [PWM(+)]PB10TCC0/WO[4]LED0
8 [PWM(-)]PB11TCC0/WO[5]
9 [IRQ/GPIO]PA16IRQ0/GPIOEDBG GPIO1
10 [SPI_SS_B/GPIO]PA27GPIO
11 [TWI_SDA]PA08SERCOM2 PAD[0] I²C SDAEXT1, EXT2, and EDBG I²C
12 [TWI_SCL]PA09SERCOM2 PAD[1] I²C SCLEXT1, EXT2, and EDBG I²C
13 [USART_RX]PA19SERCOM1 PAD[3] UART RXEXT2 UART
14 [USART_TX]PA18SERCOM1 PAD[2] UART TXEXT2 UART
15 [SPI_SS_A]PB17SERCOM5 PAD[1] SPI SS
16 [SPI_MOSI]PB22SERCOM5 PAD[2] SPI MOSIEXT2 and EDBG SPI
17 [SPI_MISO]PB16SERCOM5 PAD[0] SPI MISOEXT2 and EDBG SPI
18 [SPI_SCK]PB23SERCOM5 PAD[3] SPI SCKEXT2 and EDBG SPI
19 [GND]--Ground
20 [VCC]--Power for extension board