Table 4-2. Extension Header EXT3

Pin on EXT3

SAM R21 pin Function

Shared functionality

1 [ID]

-

Communication line to ID chip

on extension board

2 [GND]

-

GND

3 [ADC(+)]

-

-

4 [ADC(-)]

-

-

5 [GPIO1]

PA15

GPIO

6 [GPIO2]

-

7 [PWM(+)]

-

8 [PWM(-)]

-

9 [IRQ/GPIO]

-

10 [SPI_SS_B/GPIO]

PA08

GPIO

EDBG

11 [TWI_SDA]

PA16

SERCOM1 PAD[0] I²C SDA

EXT1 and EDBG

12 [TWI_SCL]

PA17

SERCOM1 PAD[1] I²C SCL

EXT1 and EDBG

13 [USART_RX]

-

-

14 [USART_TX]

-

-

15 [SPI_SS_A]

PA14

GPIO

EDBG

16 [SPI_MOSI]

PB22

SERCOM5 PAD[2] SPI MOSI

EXT1 and EDBG

17 [SPI_MISO]

PB02

SERCOM5 PAD[0] SPI MISO

EXT1 and EDBG

18 [SPI_SCK]

PB23

SERCOM5 PAD[3] SPI SCK

EXT1 and EDBG

19 [GND]

-

GND

20 [VCC]

-

VCC

Related Links

Xplained Pro Standard Extension Header on page 10

4.1.2.

Alternate Signals Header

The alternate signals header is marked with "Alternate" in silkscreen of the kit. The signals provided here

are otherwise hard to do measurements on.

Table 4-3. Alternate Signals Header

Pin on header

Pin on SAM R21

Function

1

PA09

RFCTRL1, negative antenna switch control signal

2

PA12

RFCTRL2, positive antenna switch control signal

3

PA27

GPIO, chip select on the EDBG DGI SPI bus

Atmel SAM R21 Xplained Pro [USER GUIDE]

Atmel-42243D-SAM-R21-Xplained-Pro_User Guide-04/2016

13