UG419: EFM32WG Gecko Starter Kit User's Guide
1. Introduction
The EFM32WG-STK3800 is an excellent starting point to become familiar with the EFM32WG Gecko Microcontroller. The starter kit contains sensors and peripherals demonstrating some of the EFM32WG's many capabilities. The kit provides all necessary tools for developing an EFM32WG Gecko application.
Target Device
- EFM32WG Gecko Microcontroller (EFM32WG990F256-B-BGA112)
- CPU: 32-bit ARM Cortex-M4
- Memory: 256 kB flash and 32 kB RAM
Kit Features
- USB connectivity
- Advanced Energy Monitor (AEM)
- SEGGER J-Link on-board debugger
- Debug multiplexer supporting external hardware as well as on-board MCU
- 8x20 segment LCD
- Inductive LC sensor
- Photo transistor for light sensing applications
- USB Micro-AB connector supporting both host and device mode USB applications
- 2 push buttons and 2 LEDs connected to EFM32 for user interaction
- Backup battery
- 4-segment Capacitive Touch Slider
- 20-pin 2.54 mm header for expansion boards
- Breakout pads for direct access to I/O pins
- Power sources include USB and CR2032 coin cell battery
Software Support
- Simplicity Studio
- IAR Embedded Workbench
- Keil MDK
For detailed instructions on getting started, visit the Silicon Labs website: silabs.com/mcu/32-bit/efm32-wonder-gecko
Visual Description: The page displays an image of the EFM32WG Gecko Starter Kit board, featuring the Silicon Labs logo, the EFM32WG microcontroller, an 8x20 segment LCD, various connectors, buttons, LEDs, and pin headers. A graphic with a circled '3' is also present.
2. Kit Block Diagram
The EFM32WG Gecko Starter Kit block diagram illustrates the main components and their interconnections. At the center is the EFM32WG MCU, connected via GPIO and LESENSE to peripherals such as the 8x20 Segment LCD, Light Sensor, LC Sensor, User Buttons & LEDs, and Capacitive Touch Slider. The MCU also interfaces with the Board Controller via UART and DEBUG signals. External connectivity is provided through USB Type C Connector, EXP Header, and USB Micro-AB Connector.
3. Kit Hardware Layout
The hardware layout of the EFM32WG Gecko Starter Kit is depicted, highlighting key components. These include the 8x20 Segment LCD, Debug USB Connector, CR2032 Battery Holder, Debug Connector, Simplicity Connector, Light Sensor, EFM32WG990 MCU, EXP Header, EFM32 Reset Button, Backup Battery, Inductive LC Sensor, Power Source Select switch, Capacitive Touch Slider, User LEDs, and User Push Buttons, and the EFM32 USB Connector.
4. Connectors
4.1 Breakout Pads
The EFM32WG's GPIO pins, power rails (VMCU, 3V3, 5V), and ground are accessible via two pin header rows (J101 and J102) on the top and bottom edges of the board. These headers have a standard 2.54 mm pitch. Some pins are dedicated to kit peripherals and may not be available for custom applications. The pinout tables detail the connections for the bottom row (J101) and top row (J102), specifying EFM32WG I/O pins and their shared features like LCD segments, expansion headers (EXP3, EXP4, etc.), debug signals (SWCLK, SWDIO, SWO), and user interface elements (LEDs, buttons).
4.2 EXP Header
An angled 20-pin EXP header on the right side of the board allows connection of peripherals or plugin boards. It exposes I/O pins, VMCU, 3V3, and 5V power rails. The header follows a standard for common peripherals like SPI, UART, and I2C, with other pins for general purpose I/O. This enables compatibility with expansion boards designed for various Silicon Labs kits. The pin assignment diagram and table detail connections for board identification (BOARD_ID_SDA/SCL), power, and various MCU pins mapped to peripherals like I2C, UART, SPI, and analog functions.
4.3 Debug Connector (DBG)
The debug connector supports dual purposes: connecting an external debugger to the EFM32WG (Debug IN), using the kit as a debugger for external targets (Debug OUT), or isolating the interface (Debug MCU). It follows the standard ARM Cortex Debug 19-pin connector pinout. The connector requires the board controller to be powered via the J-Link USB cable. Pin 7 is physically removed from the standard connector, which may require cable modification. The pin description table details signals like VTARGET, TMS/SWDIO/C2D, TCK/SWCLK/C2CK, TDO/SWO, TDI/C2Dps, RESET/C2CKps, and TRACE signals, along with cable detect and ground connections.
4.4 Simplicity Connector
The Simplicity Connector facilitates advanced debugging features like the Advanced Energy Monitor (AEM) and Virtual COM port for external targets. It provides VMCU, 3V3, and 5V power rails, along with virtual COM port signals (VCOM_TX, VCOM_RX, VCOM_CTS, VCOM_RTS) and Board ID signals. The pin description table outlines these connections. Note that current drawn from VMCU is monitored by AEM, but not from 3V3 or 5V pins.
5. Power Supply and Reset
5.1 MCU Power Selection
The EFM32WG can be powered via the debug USB cable, the EFM32WG's own USB regulator, or a 3V coin cell battery. A slide switch selects the power source. The 'AEM' position powers the EFM32WG via a 3.3V LDO, enabling the Advanced Energy Monitor for detailed current measurements. The 'USB' position uses the MCU's internal regulator for USB applications, disabling AEM current monitoring. The 'BAT' position uses a CR2032 coin cell battery and is recommended for external power sources, disabling current measurements.
Visual Description: A power switch diagram shows three positions: AEM (powered by 3.3V LDO from USB Type C Connector), USB (powered by EFM_USB_VBUS via USB Micro-AB Connector), and BAT (powered by 3V Lithium Battery). Each path leads to the EFM32 MCU via VMCU.
5.2 Board Controller Power
The board controller, responsible for the debugger and AEM, is powered exclusively through the USB port. It operates on a separate power domain, allowing the target device to be powered independently while maintaining debugging functionality. This isolation prevents current leakage. The board controller's power is independent of the MCU power selection switch.
5.3 EFM32WG Reset
The EFM32WG MCU can be reset by a user pressing the RESET button, the on-board debugger pulling the #RESET pin low, or an external debugger. A reset also occurs during board controller boot-up when the J-Link USB cable is connected.
6. Peripherals
6.1 Push Buttons and LEDs
The starter kit includes two user push buttons (BTN0, BTN1) connected to EFM32WG pins PB9 and PB10, respectively, with RC filters for debouncing. Two yellow LEDs (LED0, LED1) are controlled by EFM32WG GPIO pins PE2 and PE3, respectively, in an active-high configuration.
Visual Description: A diagram shows the EFM32WG microcontroller with connections to UIF_LED0, UIF_LED1, UIF_BUTTON0, and UIF_BUTTON1, representing the LEDs and buttons.
6.2 LCD
An 8x20 segment LCD is connected to the EFM32's LCD peripheral, offering 8 common lines and 20 segment lines for a total of 160 segments in octaplex mode. These lines are not shared on breakout pads. A capacitor is connected to the LCD peripheral's voltage boost pin. The diagram shows pin assignments for LCD segments (e.g., PA[6:0] to LCD_SEG[19:13]) and common lines (e.g., PB[6:3] to LCD_COM[7:4]).
Visual Description: A diagram illustrates the connections between EFM32WG pins and the 8x20 Segment LCD, showing segment and common line assignments, along with associated capacitors.
6.3 Capacitive Touch Slider
A capacitive touch slider, utilizing the EFM32WG's analog comparator (ACMP), is located on the board's underside. It features four interleaved pads connected to PC8, PC9, PC10, and PC11, corresponding to touch inputs UIF_TOUCH0 through UIF_TOUCH3. Sensing is achieved by measuring capacitance changes when a finger touches the pads, configured via ACMP in capacitive touch sensing mode and potentially scanned by LESENSE for low-power operation.
Visual Description: A diagram shows the EFM32WG microcontroller connected to a Capacitive Touch Slider, with pins PC8-PC11 mapped to touch inputs.
6.4 LC Sensor
An inductive-capacitive (LC) sensor is located on the bottom right, demonstrating the Low Energy Sensor Interface (LESENSE). It uses the VDAC to drive an oscillating current through an inductor and the ACMP to measure the decay time, which is affected by nearby metal objects. This sensor can wake the EFM32WG from sleep upon detecting metal, useful for applications like pulse counting or proximity sensing. The diagram shows connections involving PB12 (DAC_LC_EXCITE) and PC7 (LES_LC_SENSE) with associated passive components (resistors, capacitors, inductor).
Visual Description: A circuit diagram illustrates the LC Metal Sensor, showing connections from EFM32WG pins PB12 and PC7 to an LC sensor circuit comprising an inductor, capacitors, and resistors.
6.5 Ambient Light Sensor
An ambient light sensor, implemented with a TEMT6200FX01 photo transistor connected to the EFM32WG's LESENSE peripheral, is located in the top right corner. One pin (PD6) is used for excitation, and another (PC6) senses the light level. LESENSE manages both excitation and sensing. The diagram shows the connection between EFM32WG pins PD6 and PC6 and the Light Sensor.
Visual Description: A diagram shows the EFM32WG microcontroller connected to a Light Sensor via pins PD6 (LIGHT_EXCITE) and PC6 (LIGHT_SENSE), with a 22k resistor in the circuit.
6.6 USB Micro-AB Connector
The EFM32WG-STK3800 features a USB Micro-AB connector for USB host and device mode development. The board can supply 5V to USB VBUS when powered by the debug USB. An overcurrent flag is available for detecting excessive current draw. The EFM32's internal LDO powers the USB PHY. The diagram illustrates the USB connector and power supply connections, including VBUS, VREGI, VREGO, and the power selector switch.
Visual Description: A diagram shows the USB Micro-AB Connector and its related power supply circuitry, including connections to EFM32WG pins PF5 (USB_VBUSEN), PF6 (GPIO for OC_FAULT), PF10 (USB_DM), PF11 (USB_DP), and PF12 (USB_ID), along with the power selector switch.
6.7 Opamp Footprint
On the board's back side, an unpopulated operational amplifier (opamp) footprint is provided. This allows users to build custom opamp circuits by installing passive components (resistors, capacitors, inductors) connected to the EFM32WG's integrated opamp peripheral. The diagram shows the opamp symbol and connections to pins PD5 (OPAMP_OUT2), PD3 (OPAMP_N2), and PD4 (OPAMP_P2).
Visual Description: A diagram shows the EFM32WG's integrated opamp symbol with input and output connections, alongside an opamp footprint area on the board for user-added passive components.
6.8 Virtual COM Port
An asynchronous serial connection is provided via the board controller for data transfer between a host PC and the EFM32WG, eliminating the need for an external serial adapter. The Virtual COM port uses a physical UART interface consisting of two pins (VCOM_TX, VCOM_RX) and an enable signal (VCOM_EN). The diagram shows the EFM32, Board Controller, and Host Computer connected via USB, with an isolation switch in the path. The pin table lists the signals and their descriptions.
Visual Description: A diagram illustrates the Virtual COM Port interface, showing data flow (VCOM_TX, VCOM_RX) and control (VCOM_EN) between the EFM32 and the Board Controller, which then connects to a Host Computer via USB.
7. Advanced Energy Monitor
7.1 Usage
The Advanced Energy Monitor (AEM) collects data via the board controller, which can be displayed using the Energy Profiler in Simplicity Studio. This allows real-time measurement of current consumption and voltage, linked to the running code on the EFM32WG.
7.2 Theory of Operation
The AEM accurately measures current from 0.1 µA to 47 mA using a current sense amplifier and a dual gain stage. It measures the voltage drop across a small series resistor, with gain stages amplifying this voltage for two current ranges, transitioning around 250 µA. Digital filtering and averaging are performed by the board controller before data export. Automatic calibration compensates for sense amplifier offset errors.
Visual Description: A block diagram shows the AEM system, starting with a 5V input, passing through an LDO to 3.3V, then a sense resistor (4.7Ω) to the EFM32WG. The AEM Processing unit, with multiple gain stages, receives input from the current sense amplifier and connects to the EFM32WG and Peripherals. A Power Select Switch is shown between the 3.3V rail and VMCU.
7.3 Accuracy and Performance
The AEM measures currents from 0.1 µA to 47 mA. Accuracy is within 0.1 mA for currents above 250 µA and 1 µA for currents below 250 µA. It can detect current changes as small as 100 nA and produces 6250 current samples per second.
8. On-Board Debugger
The EFM32WG-STK3800 features an integrated debugger for downloading code and debugging the EFM32WG, as well as external Silicon Labs EFM32, EFM8, EZR32, and EFR32 devices. It supports Serial Wire Debug, JTAG, and C2 Debug interfaces. The debug connector on the board supports all three modes.
8.1 Debug Modes
The debugger can operate in three modes, selected via Simplicity Studio: Debug MCU: The on-board debugger is connected to the EFM32WG on the kit. Debug OUT: The on-board debugger is used to debug a supported Silicon Labs device on a custom board. Debug IN: The on-board debugger is disconnected, allowing an external debugger to connect to the EFM32WG on the kit. Debug IN requires the board controller to be powered via the Debug USB connector.
Visual Description: Three diagrams illustrate the debug modes. Debug MCU shows Host Computer -> USB -> Board Controller -> EFM32WG -> DEBUG HEADER. Debug OUT shows Host Computer -> USB -> Board Controller -> EFM32WG -> DEBUG HEADER -> External Hardware. Debug IN shows Host Computer -> USB -> Board Controller -> EFM32LG -> DEBUG HEADER -> External Debug Probe.
8.2 Debugging During Battery Operation
On-board debug functionality remains available when the EFM32WG is battery-powered and the J-Link USB is connected. If USB power is disconnected, Debug IN mode will cease. For debugging when the target is battery-powered and the board controller is off, direct connections to debugging GPIOs on the breakout pads are necessary.
9. Kit Configuration and Upgrades
9.1 Firmware Upgrades
Firmware upgrades for the kit can be performed through Simplicity Studio, which checks for updates automatically on startup. Manual upgrades are also possible via the kit configuration dialog. Users can browse for the firmware file (ending in .emz) and install it. The Simplicity Studio interface displays the adapter's debug mode and firmware version, with an option to change these settings.
Visual Description: Two screenshots show the Simplicity Studio interface. The first displays kit information including connected device, debug mode, and adapter firmware version, with a 'Change' link. The second shows the 'Kit Configuration Dialog' with options for adapter configuration, including debug mode selection.
10. Schematics, Assembly Drawings, and BOM
Schematics, assembly drawings, and bill of materials (BOM) are accessible through Simplicity Studio after installing the kit documentation package. They are also available on the Silicon Labs website.
11. Kit Revision History and Errata
11.1 Revision History
The kit revision is indicated on the box label. A table lists the kit revisions (e.g., D02, D01, D00, C01, C00, B01, B00, A01, A00) with their release dates and descriptions of changes, such as board revisions, content updates, or packaging modifications.
Visual Description: An image shows an example of kit revision information, including part number (EFM32WG-STK3800), serial number, date, quantity, and revision (Rev. D02).
11.2 Errata
There are currently no known errata for this kit.
12. Document Revision History
The document revision history tracks changes to the user guide. Version 2.00 (July 2024) updated the guide for a new board revision (BRD2400B A01). Version 1.00 (May 2020) was an update in conjunction with a new kit revision. Version 0.11 (January 2014) updated the debugger description. Version 0.10 (January 2013) was the initial document version.
Disclaimer and Trademark Information
Silicon Labs provides documentation for system and software implementers, but reserves the right to make changes without notice. The products are not authorized for FDA Class III, life support, or military applications, including weapons of mass destruction. Silicon Labs disclaims liability for unauthorized applications. Trademark information lists various Silicon Laboratories Inc. trademarks and those of other companies.
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