3.4 EXP Header
The EXP header is an angled 20-pin expansion header provided to allow connection of peripherals or plugin boards to the kit. It is loca-
ted on the right-hand side of the mainboard, and it contains a number of I/O pins that can be used with most of the EFR32 Wireless
Gecko's features. Additionally, the VMCU, 3V3, and 5V power rails are also exported.
The connector normally 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 (EXP boards) that can plug into a number of different Silicon Labs Starter Kits. However, due to limitations in the
number of available I/O pins on the EFR32xG22, the connector on this kit has a reduced feature set.
The figure below shows the pin assignment of the EXP header. Because of limitations in the number of available GPIO pins, some of
the EXP header pins are not connected and the rest 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
NC
NC
NC
NC
UART_TX / PA05
UART_RX / PA06
NC
5V
3V3
GND
NC
NC
PB00 / GPIO
PB01 / GPIO
NC
NC
NC
BOARD_ID_SDA
BOARD_ID_SCL
Reserved (Board Identification)
EFR32 I/O Pin
Figure 3.3. EXP Header
UG431: EFR32xG22 2.4 GHz 6 dBm QFN32 Wireless Starter Kit User's Guide
Connectors
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