The I/O1 Xplained Pro board should be connected to the EXT1 connector of the XMEGA A1U Xplained Pro. ATxmega128A1U SPIC on EXT1 is used for SD card communication (see Table 1). In addition, PQ2 for user button SW0 is used as Boot mode detection pin, and LED0 controlled by PQ3 indicates the programming is ongoing (see Table 2)
| Pin on EXT1 | XMEGA A1U pin | Functions for used pins |
|---|---|---|
| 1 ID | - | |
| 2 GND | - | |
| 3 ADC+ | PA0 | |
| 4 ADC- | PA4 | |
| 5 GPIO1 | PE6 | |
| 6 GPIO2 | PE7 | |
| 7 PWM+ | PE1 | |
| 8 PWM- | PE0 | |
| 9 IRQ/GPIO | PR0 | |
| 10 SPI_SS_B/GPIO | PR1 | SD card presence detection, input pin, low level stands for presence |
| 11 TWI_SDA | PC0 | |
| 12 TWI_SCL | PC1 | |
| 13 USART_RX | PC2 | |
| 14 USART_TX | PC3 | |
| 15 SPI_SS_A | PC4 | SPIC SS, SPIC used for SD Card access |
| 16 SPI_MOSI | PC5 | SPIC MOSI, SPIC used for SD card access |
| 17 SPI_MISO | PC6 | SPIC MISO, SPIC used for SD card access |
| 18 SPI_SCK | PC7 | SPIC SCK, SPIC used for SD card access |
| 19 GND | - | |
| 20 VCC | - |
| XMEGAA1U pin | Function | Description |
|---|---|---|
| PQ2 | Input pin, connected to user button SW0 | Detects this pin when starting
from reset or power on. Low level: enter Boot mode High level: go on with other detections (flash content at starting address) |
| PQ3 | Output pin, connected to LED0 and LED0 lights on with low level output on this pin | If SD card is detected in Boot mode, LED0 lights on until re-programming is finished |