3.4 Expansion Header

On the right hand side of the Wireless STK Mainboard an angled 20-pin expansion header is provided to allow connection of peripher-

als or plugin boards. The connector contains a number of I/O pins that can be used with most of the EFR32 Mighty Gecko's features.

Additionally, the VMCU, 3V3 and 5V power rails are also exported.

The connector follows a standard which ensures that commonly used peripherals such as an SPI, a UART and an I2C bus are available

on fixed locations in the connector. The rest of the pins are used for general purpose IO. This allows the definition of expansion boards

that can plug into a number of different Silicon Labs Starter Kits.

The figure below shows the pin assignment of the expansion header. Because of limitations in the number of available GPIO pins,

some of the expansion header pins are shared with kit features.

1

2

4

8

6

10

3

5

9

7

12

13

14

11

15

16

17

18

20

19

VMCU

SPI_MOSI / PA6

SPI_MISO / PA7

SPI_CLK / PA8

SPI_CS / PA9

UART_TX / PB6

UART_RX / PB7

I2C_SDA / PC11

5V

3V3

GND

PD8 / GPIO

PD9 / GPIO

PD10 / GPIO

PD11 / GPIO

PD12 / GPIO

PC9 / GPIO

PC10 / I2C_SCL

Board ID SDA

Board ID SCL

Reserved (Board Identification)

EFR32 I/O Pin

Figure 3.3. Expansion Header

UG261: EFR32MG12 2.4 GHz 10 dBm Radio Board User's Guide

Connectors

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