5. Peripherals
The starter kit has a set of peripherals that showcase some of the features of the EFR32.
Be aware that most EFR32 I/O routed to peripherals are also routed to the breakout pads or the EXP header. This must be taken into
consideration when using these.
5.1 Push Buttons and LEDs
The kit has two user push buttons marked BTN0 and BTN1. They are connected directly to the EFR32 and are debounced by RC filters
with a time constant of 1 ms. The buttons are connected to pins PB00 and Not connected.
The kit also features two yellow LEDs marked LED0 and LED1 that are controlled by GPIO pins on the EFR32. The LEDs are connec-
ted to pins PB01 and Not connected in an active-high configuration.
NC
User Buttons
& LEDs
UIF_LED0
UIF_LED1
UIF_PB0
UIF_PB1
PB00 (GPIO)
NC
PB01 (GPIO)
EFR32
Figure 5.1. Buttons and LEDs
5.2 Serial Flash
The BRD4183A Radio Board is equipped with an 8 Mbit Macronix MX25R SPI flash that is connected directly to the EFR32. The figure
below shows how the serial flash is connected to the EFR32.
PC02 (US0_CLK)
PC00 (US0_TX)
PC01 (US0_RX)
PC03 (US0_CS)
EFR32
MX25R8035F
SCLK
MOSI
MISO
SCS
VMCU
VDD
8 Mbit
Figure 5.2. Radio Board Serial Flash
The MX25R series are ultra low power serial flash devices, so there is no need for a separate enable switch to keep current consump-
tion down. However, it is important that the flash is always put in deep power down mode when not used. This is done by issuing a
command over the SPI interface. In deep power down, the MX25R typically adds approximately 100 nA to the radio board current con-
sumption.
UG431: EFR32xG22 2.4 GHz 6 dBm QFN32 Wireless Starter Kit User's Guide
Peripherals
silabs.com
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