The T9 Xplained Pro implements three Xplained Pro standard extension headers (see Section Xplained Pro Standard Extension Header) marked with EXT1 in silkscreen. These headers make it possible to connect the board to an Xplained Pro MCU board with a capacitive touch-enabled microcontroller. The pinout definition for each extension headers can be found in the table below.
| Pin on EXT1 | Function | Description |
|---|---|---|
| 1 | ID | Communication Line to ID Chip |
| 2 | GND | Ground |
| 3 | Not Connected | — |
| 4 | Not Connected | — |
| 5 | LED_2 | LED line for Sensor CS2 |
| 6 | LED_1 | LED line for Sensor CS1 |
| 7 | Y-Line-1 | For Button CS1 |
| 8 | Y-Line-2 | For Button CS2 |
| 9 | Y-Line-4 | For Button CS4 |
| 10 | Y-Line-3 | For Button CS3 |
| 11 | Not Connected | — |
| 12 | Not Connected | — |
| 13 | Not Connected | — |
| 14 | Not Connected | — |
| 15 | LED_3 | LED line for Sensor CS3 |
| 16 | LED_4 | LED line for Sensor CS4 |
| 17 | Not Connected | — |
| 18 | Not Connected | — |
| 19 | GND | Ground |
| 20 | VCC | Target Supply Voltage |