The WSTK6222 is an excellent starting point to get familiar with
the EZR32 Wonder Gecko Wireless Microcontrollers.
The Wireless Starter Kit Mainboard contains sensors and peripherals demonstrating
some of the Wireless MCU's many capabilities. The kit provides all necessary tools for
developing a Silicon Labs wireless application.
KIT FEATURES
• Ethernet and USB connectivity
• Advanced Energy Monitoring
• Packet Trace Interface support
• SEGGER J-Link OB debugger
• Debug Multiplexer supporting external
hardware as well as radio board
• Silicon Labs' Si7021 Relative Humidity and
Temperature sensor
• Ultra Low power 128x128 pixel Memory
LCD
• LEDs / Pushbuttons / Reset button
• 20pin 2.54mm header for expansion
boards
• Breakout pads for direct access to all radio
I/O pins
• Power sources including USB and CR2032
coin cell holder.
The idea behind the WSTK6222 is to provide a complete development platform for Silicon Labs EZR32 Wonder Gecko Wireless Microcontrollers. The core of the WSTK6222 is the Wireless Starter Kit (WSTK) Mainboard (BRD4001) which feature an on-board J-Link debugger, an Advanced Energy Monitor for real-time current and voltage monitoring, a Virtual COM port interface, and access to the
Packet Trace Interface (PTI). The WSTK Mainboard is paired with an EZR32 Wonder Gecko radio board that plugs directly into the
mainboard. The radio board feature the EZR32 Wonder Gecko itself and the RF interface. All debug functionality, including AEM,
VCOM and PTI, can also be used towards an external target instead of the included radio board. To further enhance the WSTK usability, the WSTK Mainboard contains sensors and peripherals demonstrating some of the Wireless MCU's many capabilities.
The EZR32 Wonder Gecko MCU on the WSTK6222 is designed to be powered by three different sources:
• Through the on-board debugger.
• Through the EZR32's own USB regulator.
• By a 3V Battery.
Selecting the power source is done with the slide switch in the lower left corner of the board. Figure Figure 4.1 WSTK6222 Power
Switch on page 4 shows how the different power sources can be selected with the slide switch.
Figure 4.1. WSTK6222 Power Switch
With the switch in the DBG position, an on-board low noise LDO with a fixed output voltage of 3.3V is used to power the MCU. This
LDO is again powered from the "J-Link" USB cable. The Advanced Energy Monitor is now also connected in series, allowing accurate
high speed current measurements and energy debugging/profiling.
With the switch in the USB position, the integrated linear regulator in the EZR32 Wonder Gecko MCU is used to power the rest of the
chip as well as the USB PHY. This allows a USB device application where the MCU acts as a bus powered device.
Finally, with the switch in the BAT position, a 20mm coin cell battery in the CR2032 socket can be used to power the device.
Note:
The Advanced Energy Monitor can only measure the current consumption of the EZR32 when the power selection switch is in the DBG
position.
4.2 Board Controller Power
The Board Controller is responsible for important features such as the debugger and the Advanced Energy Monitor, and is powered
exclusively through the USB port in the top left corner of the board. This part of the kit resides on a separate power domain, so a different power source can be selected for the MCU while retaining debugging functionality. This power domain is also isolated to prevent
current leakage from the MCU power domain when power to the Board Controller is removed.
4.3 Backup Power Domain
The kit contains a backup capacitor that can be used together with the EZR32 Wonder Gecko's backup power domain. In this case, all
other power sources are removed from the kit, and only a small part of the EZR32 runs off the capacitor. It is also possible to enter
backup mode while the Board Controller is powered by selecting either BAT or USB with no battery in the socket or USB cable in the
connector.
The EZR32 MCU can be reset by a few different sources:
• A user pressing the RESET button.
• The on-board debugger pulling the #RESET pin low.
• An external debugger pulling the #RESET pin low.
4.5 Board Controller Reset
The Board Controller can be reset by removing and re-inserting the J-Link USB cable. Removing the Board Controller USB cable will
not reset the EZR32, but whenever the Board Controller is powered up again, it will issue a RESET to the EZR32 through the on-board
debugger.
The starter kit has a set of peripherals that showcase some of the features of the EZR32 Wonder Gecko Wireless Microcontroller.
Be aware that most EZR32 I/O routed to peripherals are also routed to the breakout pads. This must be taken into consideration when
using the breakout pads for your application.
5.1 Push Buttons and LEDs
The kit has two user push buttons marked PB0 and PB1. They are connected to the EZR32, and are debounced by RC filters with a
time constant of 1ms. The buttons are connected to pins PC8 and PC9.
In addition to the two push buttons, the kit also features two yellow LEDs marked LED0 and LED1, that are controlled by GPIO pins on
the EZR32. The LEDs are connected to pins PC10 and PC11 in an active-high configuration.