Xplained Pro Standard Extension Headers

The ATtiny817 Xplained Pro headers EXT1 and EXT3 offer access to the I/O of the microcontroller to expand the board, e.g., by connecting extensions to the board. These headers are based on the standard extension header specified in the table below. The headers have a pitch of 2.54 mm.

Table 1. Extension Header EXT1
EXT1 Pin ATtiny817 Pin Function Shared Functionality
1 [ID] - - Communication line to the ID chip on an extension board
2 [GND] - - Ground
3 [ADC(+)] PA6 AIN6 QTouch Button 1
4 [ADC(-)] PA7 AIN7 QTouch Button 2
5 [GPIO1] PB7 GPIO -
6 [GPIO2] PB4 GPIO LED0
7 [PWM(+)] PB0 TC/W0 -
8 [PWM(-)] PB1 TC/W1 -
9 [IRQ/GPIO] PA5 IRQ/GPIO -
10 [SPI_SS_B/GPIO] PA4 GPIO -
11 [I²C_SDA] PA1 I²C SDA EXT3 and EDBG I²C
12 [I²C_SCL] PA2 I²C SCL EXT3 and EDBG I²C
13 [USART_RX] PB3 UART RX EXT3, EDBG CDC, and Crystal(1)
14 [USART_TX] PB2 UART TX EXT3, EDBG CDC, and Crystal(1)
15 [SPI_SS_A] PC3 SPI SS -
16 [SPI_MOSI] PC2 SPI MOSI EXT3 and EDBG SPI
17 [SPI_MISO] PC1 SPI MISO EXT3 and EDBG SPI
18 [SPI_SCK] PC0 SPI SCK EXT3 and EDBG SPI
19 [GND] - - Ground
20 [VCC] - - Power for extension board

1) Not connected by default, see Connecting the 32.768 kHz Crystal for more information.

Note: Signal functions in italic use alternative pin location. These have to be configured in the PORTMUX register of the device.
Table 2. Extension Header EXT3
EXT3 Pin ATtiny817 Pin Function Shared Functionality
1 [ID] - - Communication line to the ID chip on an extension board
2 [GND] - - Ground
3 [ADC(+)] - -  
4 [ADC(-)] - -  
5 [GPIO1] PC5 GPIO SW1 and UPDI debug connector
6 [GPIO2] - -  
7 [PWM(+)] - -  
8 [PWM(-)] - -  
9 [IRQ/GPIO] PB6 IRQ/GPIO EDBG DGI
10 [SPI_SS_B/GPIO] PB5 GPIO SW0 and EDBG DGI
11 [I²C_SDA] PA1 I²C SDA EXT1 and EDBG I²C
12 [I²C_SCL] PA2 I²C SCL EXT1 and EDBG I²C
13 [USART_RX] PB3 UART RX EXT1, EDBG CDC, and Crystal(1)
14 [USART_TX] PB2 UART TX EXT1, EDBG CDC, and Crystal(1)
15 [SPI_SS_A] PA3 GPIO / SPI_SS -
16 [SPI_MOSI] PC2 SPI MOSI EXT1 and EDBG SPI
17 [SPI_MISO] PC1 SPI MISO EXT1 and EDBG SPI
18 [SPI_SCK] PC0 SPI SCK EXT1 and EDBG SPI
19 [GND] - - Ground
20 [VCC] - - Power for extension board

1) Not connected by default, see Connecting the 32.768 kHz Crystal for more information.

Note: Signal functions in italic use alternative pin location. These have to be configured in the PORTMUX register of the device.