Power Supply; Efm8Bb52 Reset; Push Button And Led - Silicon Laboratories BB52 Explorer Kit User Manual

3.2 Power Supply

The kit is powered by the debug USB cable as illustrated in the figure below.
USB Micro-B
The 5 volt power net on the USB bus is regulated down to 3.3 V using an LDO (low-dropout regulator). An automatic isolation circuit
isolates the LDO when the USB cable is not plugged in.
Power can be injected externally on the VMCU net if the USB cable is removed and no other power sources are present on the kit.
Failure to follow this guideline can cause power conflicts and damage the LDO.

3.3 EFM8BB52 Reset

The EFM8BB52 can be reset by a few different sources:
• A user pressing the RESET button.
• The on-board debugger pulling the #RESET pin low.

3.4 Push Button and LED

The kit has one user push button, marked BTN0, that is connected to a GPIO on the EFM8BB52. The button is connected to pin P0.2
and it is debounced by an RC filter with a time constant of 1 ms. The logic state of the button is high while the button is not being
pressed, and low when the button is pressed.
The kit also features one yellow LED, marked LED0, that is controlled by a GPIO pin on the EFM8BB52. The LED is connected to pin
P1.4 in an active-high configuration.
EFM8BB52
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5V0 3V3
IN OUT
LDO
Figure 3.2. BB52 Explorer Kit Power Topology
BB52_BUTTON0
P0.2
BB52_LED0
P1.4
Figure 3.3. Button and LED
Automatic
Isolation
VMCU
Peripherals
EFM8BB52
8-bit MCU
Peripherals
Button & LED
UG512: BB52 Explorer Kit User's Guide
Hardware
User
Rev. 1.0 | 7