Silicon Laboratories UG464 User manual

UG464: Thunderboard™ EFR32BG22
User's Guide
The Thunderboard™ EFR32BG22 is a low cost, small form factor
prototype and development platform for the EFR32BG22 Wireless
Gecko System-on-Chip.
The board is a small and cost effective, feature rich, prototype and development platform
based on the EFR32™ Wireless Gecko System-on-Chip. The Thunderboard
EFR32BG22 is an ideal platform for developing energy-friendly connected IoT devices.
The Thunderboard EFR32BG22 ships with a Bluetooth demo that works with a cloud
connected smartphone app, showcasing easy collection of environmental and motion
sensor data, as well as button and LED control.
A built in SEGGER J-Link debugger ensures easy debugging through the USB Micro-B
connector.
TARGET DEVICE
• EFR32 Wireless Gecko System-on-Chip
(EFR32BG22C224F512IM40)
• 32-bit ARM® Cortex®-M33 with 76.8
MHz maximum operating frequency
• 512 kB flash and 32 kB RAM
• Energy-efficient radio core with low
active and sleep currents
• Bluetooth 5.2 Direction Finding
• Integrated PA with up to 6 dBm (2.4
GHz) TX power
• Secure Boot with Root of Trust and
Secure Loader (RTSL)
KIT FEATURES
• 2.4 GHz ceramic chip antenna
• Power control of on-board peripherals for
ultra low power operation
• Relative humidity and temperature sensor
• Ambient light sensor
• Hall effect sensor
• 6-axis inertial sensor
• PDM stereo microphones
• 8 Mbit flash for OTA programming and
data logging
• User LED and push button
• 20-pin 2.54 mm breakout pads
• SEGGER J-Link on-board debugger
• Virtual COM port
• Packet Trace Interface (PTI)
• Mini Simplicity connector for AEM and
packet trace using external Silicon Labs
debugger
• USB or coin cell battery powered.
SOFTWARE SUPPORT
• Simplicity Studio™
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Table of Contents
1. Introduction ................................4
1.1 Kit Contents ...............................4
1.2 Getting Started ..............................4
1.3 Hardware Content .............................4
1.4 Kit Hardware Layout ............................5
2. Specifications ...............................6
2.1 Recommended Operating Conditions ......................6
2.2 Current Consumption ............................7
3. Hardware .................................9
3.1 Block Diagram ..............................9
3.2 Power Supply ..............................10
3.3 EFR32BG22 Reset ............................10
3.4 Peripherals ...............................11
3.4.1 Si7021 Relative Humidity and Temperature Sensor ................12
3.4.2 Si7210 Hall Effect Sensor .........................12
3.4.3 VEML6035 Ambient Light Sensor ......................13
3.4.4 PDM Stereo Microphones .........................13
3.4.5 ICM-20648 6-Axis Inertial Sensor ......................14
3.4.6 Push Button and LED ..........................15
3.4.7 External Memory ............................15
3.5 On-board Debugger ............................16
3.6 Connectors ...............................17
3.6.1 Breakout Pads ............................18
3.6.2 Mini Simplicity Connector .........................19
3.6.3 Debug USB Micro-B Connector .......................19
4. Debugging ...............................20
4.1 On-board Debugger ............................21
4.2 External Debugger.............................21
4.3 Virtual COM Port .............................22
5. Radio .................................23
5.1 RF Section ...............................23
5.1.1 Description of the RF Matching .......................23
5.1.2 RF Section Power Supply .........................23
5.1.3 RF Matching Bill of Materials ........................23
5.1.4 Antenna ...............................24
5.1.5 Antenna Matching Bill of Materials ......................24
5.2 EMC Regulations for 2.4 GHz .........................24
5.2.1 ETSI EN 300-328 Emission Limits for the 2400-2483.5 MHz Band ...........24
5.2.2 FCC15.247 Emission Limits for the 2400-2483.5 MHz Band .............24
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5.2.3 Applied Emission Limits .........................25
5.3 Relaxation with Modulated Carrier .......................25
5.4 Radiated Power Measurements ........................26
5.4.1 Maximum Radiated Power Measurement ...................26
5.4.2 Antenna Pattern Measurement .......................27
5.5 EMC Compliance Recommendations ......................29
5.5.1 Recommendations for 2.4 GHz ETSI EN 300-328 Compliance ............29
5.5.2 Recommendations for 2.4 GHz FCC 15.247 Compliance ..............29
6. Schematics, Assembly Drawings, and BOM ...................30
7. Kit Revision History ............................31
8. Board Revision History and Errata ......................32
8.1 Revision History .............................32
8.2 Errata .................................32
9. Document Revision History .........................33
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1. Introduction
The Thunderboard EFR32BG22 (OPN: SLTB010A) has been designed to inspire customers to make battery operated IoT devices with
the Silicon Labs EFR32BG22 Wireless Gecko System-on-Chip. The highlights of the board include four different environmental sensors
and stereo PDM microphones accessible to the EFR32BG22 wireless MCU. The peripherals have been grouped into power domains
that can be turned on and off by the application code as needed.
Programming the Thunderboard EFR32BG22 is easily done using a USB Micro-B cable and the on-board J-Link debugger. A USB vir-
tual COM port provides a serial connection to the target application, and the Packet Trace Interface (PTI) offers invaluable debug infor-
mation about transmitted and received packets in wireless links. Included on the board is an 8 Mbit serial flash that can be used for
Over-The-Air (OTA) firmware upgrade, or as a general purpose non-volatile memory. The Thunderboard EFR32BG22 is supported in
Simplicity Studio™, and a Board Support Package (BSP) is provided to give application developers a flying start.
Energy profiling and advanced wireless network analysis and debugging tools are available through the provided Mini Simplicity Con-
nector using an external Silicon Labs debugger.
Connecting external hardware to the Thunderboard EFR32BG22 can be done using the 20 breakout pads which present peripherals
from the EFR32BG22 Wireless Gecko such as I2C, SPI, UART and GPIOs. The breakout pads follow the same pinout as the expansion
headers (EXP) on other Silicon Labs Starter Kits.
1.1 Kit Contents
The following items are included in the box:
• 1x Thunderboard EFR32BG22 board (BRD4184B)
• 1x USB Type A to Micro-B cable.
1.2 Getting Started
Detailed instructions for how to get started with your new Thunderboard EFR32BG22 can be found on the Silicon Labs web pages:
https://www.silabs.com/support/getting-started/thunderboard
1.3 Hardware Content
The following key hardware elements are included on the Thunderboard EFR32BG22:
• EFR32BG22 Wireless Gecko SoC with 76.8 MHz operating frequency, 512 kB kB flash and 32 kB RAM
• 2.4 GHz ceramic antenna for wireless transmission
• Silicon Labs Si7021 relative humidity and temperature sensor
• Silicon Labs Si7210 hall effect sensor
• Vishay VEML6035 ambient light sensor
• TDK InvenSense ICM-20648 6-axis inertial sensor
• Two Knowles SPK0641HT4H-1 MEMS microphones
• Macronix ultra low power 8 Mbit SPI flash (MX25R8035F)
• One LED and one push button
• Power enable signals and isolation switches for ultra low power operation
• On-board SEGGER J-Link debugger for easy programming and debugging, which includes a USB virtual COM port and Packet
Trace Interface (PTI)
• Mini Simplicity connector for access to energy profiling and advanced wireless network debugging
• Breakout pads for GPIO access and connection to external hardware
• Reset button
• Automatic switchover between USB and battery power
• CR2032 coin cell holder
UG464: Thunderboard™ EFR32BG22 User's Guide
Introduction
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1.4 Kit Hardware Layout
The layout of the Thunderboard EFR32BG22 is shown below.
Top View Bottom View
Push Button
30.4 mm
45.4 mm
Reset Button
20-pin EXP-header
Breakout Pads
6-axis
Inertial Sensor
USB Micro-B Connector
- Virtual COM port
- Debug access
- Packet trace
Hall Effect
Sensor
Humidity and
Temperature Sensor
Mini Simplicity
Connector
Ambient
Light
Sensor
EFR32BG22
Wireless Gecko
2.4 GHz
Chip Antenna
On-board USB
J-Link Debugger
CR2032 Coin Cell
Holder
Left PDM
Microphone
Right PDM
Microphone
LED
Figure 1.1. Thunderboard EFR32BG22 Hardware Layout
UG464: Thunderboard™ EFR32BG22 User's Guide
Introduction
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2. Specifications
2.1 Recommended Operating Conditions
The following table is intended to serve as guideline for a correct use of Thunderboard EFR32BG22, indicating typical operating condi-
tions and some design limits.
Table 2.1. Recommended Operating Conditions
Parameter Symbol Min Typ Max Unit
USB Supply Input Voltage VUSB — 5.0 — V
Battery Supply Input Voltage VVBAT 2.0 3.0 3.3 V
Supply Input Voltage (VMCU supplied externally)1,2 VVMCU 2.0 3.0 3.6 V
Operating Temperature TOP — 20 — ˚C
Note:
1. The maximum supply voltage may be less under certain conditions when using the EFR32BG22's dc-dc converter. For more in-
formation see the EFR32BG22 data sheet.
2. Not recommended for use with rechargeable Lithium batteries. Most Li-Ion and Li-Po cells exceed 3.6 V when fully charged.
UG464: Thunderboard™ EFR32BG22 User's Guide
Specifications
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2.2 Current Consumption
The table below summarizes the data sheet current consumption of the various components on the board. The operating current of the
board greatly depends on the application. The number of enabled sensors, how often they are sampled and how often the radio is
transmitting or receiving are examples of factors that influence the operating current. In many cases the given conditions differ from the
operating conditions on the Thunderboard EFR32BG22, but the table can still be used as an indication of how much each feature con-
tribute to the total current consumption. More details can be found in the specific data sheet for each device.
Table 2.2. Current Consumption
Parameter Symbol Condition Typ Unit
EFR32BG22 Current Con-
sumption1
IEFR32 MCU current consumption in EM0 mode with all peripher-
als disabled (dc-dc converter at 3.0 V input and 1.8 V out-
put, VSCALE1, 38.4 MHz crystal, CPU running Prime from
flash at 25 ˚C)
28 µA/MHz
EM4, no BURTC, no LF oscillator 0.17 µA
Radio system current consumption in receive mode, active
packet reception (dc-dc converter at 3.0 V input and 1.8 V
output, MCU in EM1 and all MCU peripherals disabled,
HCLK = 38.4 MHz, 1Mbit/s, 2GFSK, f = 2.4 GHz,
VSCALE1 at 25 ˚C)
3.8 mA
Radio system current consumption in transmit mode (dc-
dc converter at 3.0 V input and 1.8 V output, MCU in EM1
and all MCU peripherals disabled, HCLK = 38.4 MHz, f =
2.4 GHz, CW, 6 dBm output power, VSCALE1 at 25 ˚C)
8.4 mA
Ambient Light Sensor Cur-
rent Consumption 2
IVEML6035 Shutdown at 1.8 V 0.5 µA
Operation mode at 1.8 V (ALS only) 170 µA
RH/Temp Sensor Current
Consumption3
ISi7021 Standby, -40 to +85˚C 0.06 µA
RH conversion in progress 150 µA
Temperature conversion in progress 90 µA
Peak IDD during I2C operations 3.5 mA
Hall Effect Magnetic Sensor
Current Consumption 4
IDD Sleep mode at 3.3 V 50 nA
Average current for periodic activation at 3.3 V, sleep tim-
er enabled, 200 msec sleep time
0.4 µA
Conversion in progress at 3.3 V 5 mA
Microphone Current Con-
sumption5
IMIC Sleep mode current (Fclock = 0 Hz, VDD = 3.6 V) 26 µA
Supply current in performance mode (VDD = 3.6 V, Fclock
= 2.4 MHz)
700 µA
IMU Current Consumption6IIMU Full-chip sleep mode at 1.8 V supply 8 µA
Gyroscope Only, 102.3 Hz update rate at 1.8 V supply 1.23 mA
Accelerometer only, 102.3 Hz update rate at 1.8 V supply 68.9 µA
Gyroscope + Accelerometer, 102.3 Hz update rate at 1.8
V supply
1.27 mA
Serial Flash Memory Cur-
rent Consumption 7
IFlash Deep power-down current in ultra low power mode at 1.8
V
0.007 µA
Standby current in ultra low power mode at 1.8 V 5 µA
Write status register current in ultra low power mode at 1.8
V
3.1 mA
UG464: Thunderboard™ EFR32BG22 User's Guide
Specifications
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Parameter Symbol Condition Typ Unit
On-board Debugger Sleep
Current Consumption 8
IDBG On-board debugger current consumption when USB cable
is not inserted (EFM32GG12 EM4S mode current con-
sumption)
80 nA
Minimum Board Current
Consumption
IBOARD Minimum total board current consumption for VMCU = 3.0
V with EFR32BG22 in EM4S, the USB cable disconnec-
ted, and all peripherals either in sleep mode or disconnec-
ted
0.4 µA
Note:
1. From EFM32BG22 data sheet
2. From VEML6035 data sheet
3. From Si7021-A20 data sheet
4. From Si7210 data sheet
5. From SPK0641HT4H-1 data sheet
6. From ICM-20648 data sheet
7. From MX25R8035F data sheet
8. From EFM32GG12 data sheet
UG464: Thunderboard™ EFR32BG22 User's Guide
Specifications
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3. Hardware
The core of the Thunderboard EFR32BG22 is the EFR32BG22 Wireless Gecko System-on-Chip. The board also contains several pe-
ripherals connected to the EFR32BG22. For placement and layout of the hardware components the reader is referred to section 1.4 Kit
Hardware Layout.
3.1 Block Diagram
An overview of the Thunderboard EFR32BG22 is illustrated in the figure below.
Memory
Sensors
Radio
Device Connectivity & Debugging
J-Link
Debugger
USB Micro-B
Connector
2.4 GHz
Antenna
8 Mbit
MX25R
Button and LED
EFR32BG22
Wireless SoC
Breakout Pads
(EXP-Header pinout)
Si7021 Si7210
VEML6035
Temperature
& Humidity
Sensor
Ambient
Light
Sensor
Hall Effect
Sensor
SPK0641HT4H-1 ICM-20648
2x PDM
Microphones
6-axis Inertial
Sensor
User Button
& LED
Mini-Simplicity
Connector
Serial Flash
Figure 3.1. Kit Block Diagram
UG464: Thunderboard™ EFR32BG22 User's Guide
Hardware
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3.2 Power Supply
The kit can be powered through one of these interfaces:
• USB Micro-B
• Battery
• Mini Simplicity connector
The figure below shows the power options available on the kit and illustrates the main system power architecture.
USB Micro-B LDO
5V0
IN OUT
Automatic
Switchover
3V0
VMCU
Battery
EFR32BG22
Wireless SoC
Peripherals
Peripherals
Peripherals
Peripherals
Mini Simplicity
Connector
Figure 3.2. Thunderboard EFR32BG22 Power Architecture
Power is normally applied either through the USB cable or a CR2032 battery. When the USB cable is connected, VBUS is regulated
down to 3.0 V. An automatic switchover circuit switches the main system power from battery power to USB power when the USB cable
is inserted, and protects the battery from reverse current.
Power can also be applied through the Mini Simplicity connector. This requires that no other power sources are present on the kit, as
power is injected directly to the VMCU net. It is important to follow this in order to avoid power conflicts and backfeeding the battery.
Powering the Thunderboard EFR32BG22 through the Mini Simplicity connector allows current measurements using the Advanced En-
ergy Monitoring (AEM) as described in section 4.2 External Debugger.
Important: When powering the board through the Mini Simplicity connector, the USB and battery power sources must be removed.
The power supply options are summarized in the table below.
Table 3.1. Thunderboard EFR32BG22 Power Options
Supply Mode Typical Input Voltage VMCU Source 3V0 5V
USB power 5.0 V On-board regulator On-board regulator USB VBUS
CR2032 battery 3.0 V Battery voltage Disconnected No voltage present
Mini Simplicity 3.3 V Debugger dependent Disconnected No voltage present
3.3 EFR32BG22 Reset
The EFR32BG22 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.
UG464: Thunderboard™ EFR32BG22 User's Guide
Hardware
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3.4 Peripherals
The Thunderboard EFR32BG22 contains a set of peripherals that can be accessed from the EFR32BG22. All the peripherals have ena-
ble signals which can be used to completely turn off the peripherals that are not in use, or they can be put into a state that draws minus-
cule amount of power. This allows for the lowest possible power consumption in every application. The following peripherals are acces-
sible to the EFR32BG22:
• One Silicon Labs Si7021 relative humidity & temperature sensor
• One Silicon Labs Si7210 hall effect sensor
• One Vishay VEML6035 ambient light sensor
• One TDK InvenSense ICM-20648 6-axis inertial measurement sensor
• Two Knowles SPK0641HT4H-1 MEMS microphones with PDM output
• One Macronix MX25R8035F ultra low power 8 Mbit SPI flash
• One LED and one push button
The figure below gives an overview of the peripherals that are connected to the EFR32BG22. Note that some of the peripherals share
the same interface and enable signals. As the enable signals does not have external pull-down resistors on the board, the application
code should actively drive the signals either low or high to prevent the lines from floating.
PC10 (I2C0_SCL#14)
PC11 (I2C0_SDA#16)
EFR32BG22
ICM-20648
MX25R
VMCU
Si7021
VEML6035
2x SPK0641HT4H-1
Si7210
VMCU
I2C
SENSOR ENABLE
VMCU
PDM
MIC ENABLE
IMU ENABLE
SPI IMU CS
SPI
VMCU
SPI FLASH CS
IMU INTERRUPT
8 Mbit
Flash
3
2
2
Button LED
GPIOGPIO
Figure 3.3. Peripherals
UG464: Thunderboard™ EFR32BG22 User's Guide
Hardware
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3.4.1 Si7021 Relative Humidity and Temperature Sensor
The Si7021 I2C relative humidity and temperature sensor is a monolithic CMOS IC integrating humidity and temperature sensor ele-
ments, an analog-to-digital converter, signal processing, calibration data, and an I2C interface. The patented use of industry-standard,
low-K polymeric dielectrics for sensing humidity enables the construction of low-power, monolithic CMOS Sensor ICs with low drift and
hysteresis, and excellent long term stability. The Si7021 offers an accurate, low-power, factory-calibrated digital solution ideal for meas-
uring humidity, dew-point, and temperature, in applications ranging from HVAC/R and asset tracking to industrial and consumer plat-
forms.
On Thunderboard EFR32BG22, the Si7021 is connected through a switch. The switch must therefore be enabled by setting
EFR32_SENSOR_EN high before it can be used by the application. This enables power to the Si7021 and connects the I2C lines used
for the sensor to the EFR32BG22 I2C bus. The application code should always drive the EFR32_SENSOR_EN signal either high or low
to prevent it from floating. The figure below shows how the Si7021 is connected to the EFR32BG22.
Si7021
Temperature
& Humidity
Sensor
VMCU
EFR32BG22
PD03 (I2C0.SCL)
PD02 (I2C0.SDA)
PC06 (GPIO)
VDD_SENSOR
EFR32_I2C_SCL
EFR32_I2C_SDA
EFR32_SENSOR_ENABLE
SENSOR_I2C_SCL
SENSOR_I2C_SDA
0: Sensor is not powered
1: Sensor is powered
Figure 3.4. Si7021 Relative Humidity and Temperature Sensor
Although measures have been taken to thermally isolate the sensor from the board, temperature readings will be influenced when pow-
er is dissipated on the board. More accurate temperature measurements are achieved when powering the board with a battery or
through the Mini Simplicity connector as self-heating from the on-board LDO is eliminated and the on-board debugger is put in a low
power state.
3.4.2 Si7210 Hall Effect Sensor
The Si7210 family of Hall effect sensors from Silicon Labs combines a chopper-stabilized Hall element with a low-noise analog amplifi-
er, 13-bit analog-to-digital converter, and an I2C interface. Leveraging Silicon Labs' proven CMOS design techniques, the Si7210 family
incorporates digital signal processing to provide precise compensation for temperature and offset drift. The 13-bit magnetic field
strength can be read through the I2C interface at any time. Applications for the Si7210 include mechanical position sensing in consum-
er, industrial and automotive applications, reed switch replacement, fluid level measurement, speed sensing and control knobs and
switches.
On Thunderboard EFR32BG22, the Si7210 is connected through a switch. The switch must therefore be enabled by setting
EFR32_SENSOR_EN high before it can be used by the application. This enables power to the Si7210 and connects the I2C lines used
for the sensor to the EFR32BG22 I2C bus. The application code should always drive the EFR32_SENSOR_EN signal either high or low
to prevent it from floating. The figure below shows how the Si7210 is connected to the EFR32BG22.
VMCU
EFR32BG22
PD03 (I2C0.SCL)
PD02 (I2C0.SDA)
PC06 (GPIO)
VDD_SENSOR
EFR32_I2C_SCL
EFR32_I2C_SDA
EFR32_SENSOR_ENABLE
SENSOR_I2C_SCL
SENSOR_I2C_SDA
0: Sensor is not powered
1: Sensor is powered
Si7210
Hall Effect
Sensor
Figure 3.5. Hall Effect Sensor
UG464: Thunderboard™ EFR32BG22 User's Guide
Hardware
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3.4.3 VEML6035 Ambient Light Sensor
The VEML6035 is an ambient light sensor with I2C digital interface.
On Thunderboard EFR32BG22, the VEML6035 is connected through a switch. The switch must therefore be enabled by setting
EFR32_SENSOR_EN high before it can be used by the application. This enables power to the VEML6035 and connects the I2C lines
used for the sensor to the EFR32BG22 I2C bus. The application code should always drive the EFR32_SENSOR_EN signal either high
or low to prevent it from floating. The figure below shows how the VEML6035 is connected to the EFR32BG22.
VMCU
EFR32BG22
PD03 (I2C0.SCL)
PD02 (I2C0.SDA)
PC06 (GPIO)
VDD_SENSOR
EFR32_I2C_SCL
EFR32_I2C_SDA
EFR32_SENSOR_ENABLE
SENSOR_I2C_SCL
SENSOR_I2C_SDA
0: Sensor is not powered
1: Sensor is powered
VEML6035
Ambient
Light Sensor
Figure 3.6. VEML6035 Ambient Light Sensor
3.4.4 PDM Stereo Microphones
The Thunderboard EFR32BG22 features two Knowles SPK0641HT4H-1 digital MEMS microphones with PDM output. The micro-
phones are configured to form a stereo sound input device using only a single PDM data line. The clock to the microphones are fed
from a pin on EFR32BG22 with PDM clock support. The output from both microphones are connected to the same line and connected
to a pin on the EFR32BG22 supporting PDM data input.
On Thunderboard EFR32BG22, the microphones are connected through a switch. The switch must therefore be enabled by setting
EFR32_MIC_EN high before it can be used by the application. This enables power to the microphones and connects the PDM lines
used for the sensor to the EFR32BG22. The application code should always drive the EFR32_MIC_EN signal either high or low to pre-
vent it from floating. The figure below shows how the microphones are connected to the EFR32BG22.
VMCU
SPK0641HT4H-1
PDM
Microphone (R)
SPK0641HT4H-1
PDM
Microphone (L)
EFR32BG22
PB00 (PDM.CLK)
PB01 (PDM.DAT0)
PC07 (GPIO)
VDD_MIC
EFR32_PDM_CLK
EFR32_PDM_DATA
EFR32_MIC_ENABLE
MIC_PDM_CLK
MIC_PDM_DATA VDD_MIC
VDD_MIC
0: Sensor is not powered
1: Sensor is powered
Figure 3.7. Digital Stereo Microphones
UG464: Thunderboard™ EFR32BG22 User's Guide
Hardware
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3.4.5 ICM-20648 6-Axis Inertial Sensor
The ICM-20648 is a 6-axis inertial sensor consisting of a 3-axis gyroscope and a 3-axis accelerometer. The sensor detects acceleration
and angular rate in and around the X-, Y- and Z-axes with integrated 16-bit ADCs and programmable digital filters.
On Thunderboard EFR32BG22, the ICM-20648 is connected through a switch. The switch must be enabled by setting EFR32_IMU_EN
high before it can be used by the application. This enables power to the ICM-20648 and connects the SPI lines used for the sensor to
the EFR32BG22 SPI bus. The application code should always drive the EFR32_IMU_EN signal either high or low to prevent it from
floating. Note the presence of the external pull-up resistor on the interrupt line as this can cause back powering if not handled correctly
in software. The figure below shows how the ICM-20648 is connected to the EFR32BG22.
VMCU
EFR32BG22
PC02 (US0.CLK)
PC00 (US0.TX)
PB04 (GPIO)
EFR32_SPI_SCLK
EFR32_SPI_MOSI
EFR32_IMU_ENABLE
IMU_SPI_SCLK
IMU_SPI_MOSI
0: Sensor is not powered
1: Sensor is powered
ICM-20648
6-axis Intertial
Sensor
EFR32_SPI_MISO
PC01 (US0.RX) IMU_SPI_MISO
IMU_SPI_CS#
VDD_IMU
EFR32_IMU_INT
PA00 (GPIO)
EFR32_SPI_IMU_CS#
PB02 (US0.CS)
Figure 3.8. ICM-20648 Six-axis Inertial Sensor
The inertial sensor is located close to the geometrical center of the board. The coordinate system and rotation of the sensor follows the
right-hand rule, and the spatial orientation of the board is shown in the figure below.
Figure 3.9. Thunderboard EFR32BG22 Spatial Orientation
UG464: Thunderboard™ EFR32BG22 User's Guide
Hardware
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3.4.6 Push Button and LED
The kit has one user push button, marked BTN0, that is connected to a GPIO on the EFR32BG22. The button is connected to pin PB03
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 EFR32BG22. The LED is connected to pin
PA04 in an active-high configuration.
EFR32BG22
EFR32_LED0
EFR32_BUTTON0
User
Button & LED
PB03 (GPIO.EM4WU4)
PA04 (GPIO)
Figure 3.10. Button and LED
3.4.6.1 GPIOs on Unused JTAG Debug Pins
The EFR32BG22 allows the PA04 pin, which is connected to TDI on the JTAG Debug Port, to be used for other purposes if JTAG is not
used. The Thunderboard EFR32BG22 uses SWD as debugging interface and the PA04 pin of the EFR32BG22 is used to control LED0.
Under certain circumstances, such as an unexpected reset during a debug session, control of the PA04 pin can be transferred to the
debug port which will result in the user application losing control of the PA04 pin. If this happens, known workarounds are to disconnect
all active debug sessions and then reset the EFR32BG22 through either the reset pin or by toggling the power.
3.4.7 External Memory
The Thunderboard EFR32BG22 includes an 8 Mbit Macronix SPI Flash that is connected directly to the EFR32BG22. The MX25R ser-
ies are ultra low power serial flash devices, so there is no need for a separate enable switch to keep current consumption down. How-
ever, 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 current consumption. The figure below
shows how the serial flash is connected to the EFR32BG22.
EFR32BG22
Serial Flash
8 Mbit
MX25R
EFR32_SPI_MOSI
EFR32_SPI_MISO
EFR32_SPI_FLASH_CS#
VMCU
EFR32_SPI_SCLK
PC02 (US0.CLK)
PC00 (US0.TX)
PC01 (US0.RX)
PC03 (US0.CS)
Figure 3.11. Serial Flash
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3.5 On-board Debugger
The Thunderboard EFR32BG22 contains a microcontroller separate from the EFR32BG22 Wireless Gecko that provides the user with
an on-board J-Link debugger through the USB Micro-B port. This microcontroller is referred to as the "on-board debugger", and is not
programmable by the user. When the USB cable is removed, the on-board debugger goes into a very low power shutoff mode (EM4S).
In addition to providing code download and debug features, the on-board debugger also presents a virtual COM port for general pur-
pose application serial data transfer. The Packet Trace Interface (PTI) is also supported which offers invaluable debug information
about transmitted and received packets in wireless links.
The figure below shows the connections between the target EFR32BG22 device and the on-board debugger. The figure also shows the
presence of the Mini Simplicity Connector, and how this is connected to the same I/O pins.
Please refer to chapter 4. Debugging for more details on debugging.
Mini Simplicity
Connector
EFR32MG
EFR32BG22
PA01 (GPIO.SWCLK)
PA02 (GPIO.SWDIO)
PA03 (GPIO.SWV)
PA05 (USART1.TX)
PA06 (USART1.RX)
PA07 (USART1.RTS)
PA08 (USART1.CTS)
DBG_VCOM_TX
DBG_VCOM_RX
DBG_VCOM_CTS
DBG_VCOM_RTS
DBG_SWCLK
DBG_SWDIO
DBG_SWO
On-Board
J-Link
Debugger
Host
PC USB
DBG_PTI_DATA PC04 (FRC.DOUT)
PC05 (FRC.DFRAME)
DBG_PTI_FRAME
DBG_RESET RESETn
Figure 3.12. On-Board Debugger Connections
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3.6 Connectors
Featured on the Thunderboard EFR32BG22 is a Mini Simplicity Connector, a USB Micro-B connector and 20 breakout pads that follow
the EXP header pinout. The connectors are placed on the top side of the board, and their placement and pinout can be seen in the
figure below. For additional information on the connectors see the following sub chapters.
2
4
6
8
10
12
14
16
18
20
1
3
5
7
9
11
13
15
17
19
EXP2 - VMCU
EXP4 - SPI_MOSI - PC0
EXP18 - 5V
EXP20 - 3V0
EXP6 - SPI_MISO - PC1
EXP8 - SPI_SCLK - PC2
EXP10 - SPI_CS - PB2
EXP12 - UART_TX - PA5
EXP14 - UART_RX - PA6
EXP16 - I2C_SDA - PD2
GND - EXP1
PA8 - EXP3
PA7 - EXP5
PB0 - EXP7
PB1 - EXP9
PA4 - EXP11
PB3 - EXP13
PD3 - I2C_SCL - EXP15
BOARD_ID_SCL - EXP17
BOARD_ID_SDA - EXP19
Expansion Header
Breakout Pads
VMCU
RST
PA5 - VCOM_TX
PA2 - SWDIO
PC5 - PTI_FRAME
GND
VCOM_RX - PA6
SWO - PA3
SWCLK - PA1
PTI_DATA - PC4
Mini Simplicity
Connector
USB Micro-B
Connector
Mini-Simplicity
Connector
Pin 1
Figure 3.13. Thunderboard EFR32BG22 Connectors
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3.6.1 Breakout Pads
20 breakout pads, which follow the EXP header pinout, are provided, and allow connection of peripherals or add-on boards. Ten of the
pads are located along the left side of the board and ten are located on the right side. The breakout pads expose I/O pins that can be
used with most of the EFR32BG22's features. Additionally, the VMCU (main power rail), 3V0 (LDO regulator output) and 5V power rails
are also exposed.
The breakout pads are pinned out similar to the EXP header found on other Silicon Labs Starter Kits, which ensures that commonly
used peripherals such as SPI, UART and I2C buses are available on fixed locations. The rest of the pins are used for general purpose
IO. This allows the definition of EXP boards that can plug into a number of different Silicon Labs starter kits.
The pin-routing on EFR32 is very flexible, so most peripherals can be routed to any pin. However, pins may be shared between the
breakout pads and other functions on the Thunderboard EFR32BG22. The table below includes an overview of the EXP header and
functionality that is shared with the kit.
Table 3.2. Expansion Header Pinout
Pin Connection EXP Header Function Shared Feature Peripheral Mapping
Right Side Breakout Pins
2 VMCU EFR32BG22 voltage domain, included in AEM measurements.
4 PC00 SPI_MOSI IMU & Flash US0_TX
6 PC01 SPI_MISO IMU & Flash US0_RX
8 PC02 SPI_SCLK IMU & Flash US0_CLK
10 PB02 SPI_CS IMU US0_CS
12 PA05 UART_TX Virtual COM Port US1_TX
14 PA06 UART_RX Virtual COM Port US1_RX
16 PD02 I2C_SDA Sensor I2C bus I2C0_SDA
18 5V Board USB voltage
20 3V0 Board controller supply
Left Side Breakout Pins
1 GND Ground
3 PA08 GPIO Virtual COM Port —
5 PA07 GPIO Virtual COM Port —
7 PB00 GPIO PDM Microphones —
9 PB01 GPIO PDM Microphones —
11 PA04 GPIO LED —
13 PB03 GPIO Button —
15 PD03 I2C_SCL Sensor I2C bus I2C0_SCL
17 BOARD_ID_SCL Connected to Board Controller for identification of add-on boards.
19 BOARD_ID_SDA Connected to Board Controller for identification of add-on boards.
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3.6.2 Mini Simplicity Connector
The Mini Simplicity connector is a 10-pin 1.27 mm pitch connector that allows the use of an external debugger such as the one found
on a Silicon Labs Wireless Starter Kit (WSTK) mainboard. See section 4.2 External Debugger for more details. The pinout of the con-
nector on the board is described in the table below with the names being referenced from the EFR32BG22.
Table 3.3. Mini Simplicity Connector Pin Descriptions
Pin number Connection Function Description
1 VMCU VAEM Target voltage on the debugged application. Supplied and monitored
by the AEM when powered by a WSTK with its power selection switch
in the "AEM" position.
2 GND GND Ground.
3 EFR32BG22 reset pin DBG_RST Reset.
4 PA06 VCOM_RX Virtual COM Rx.
5 PA05 VCOM_TX Virtual COM Tx.
6 PA03 DBG_SWO Serial Wire Output.
7 PA02 DBG_SWDIO Serial Wire Data.
8 PA01 DBG_SWCLK Serial Wire Clock.
9 PC05 PTI_FRAME Packet Trace Frame Signal.
10 PC04 PTI_DATA Packet Trace Data Signal.
3.6.3 Debug USB Micro-B Connector
The debug USB port can be used for uploading code, debugging, and as a Virtual COM port. More information is available in section
4. Debugging.
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4. Debugging
The Thunderboard EFR32BG22 contains an on-board SEGGER J-Link Debugger that interfaces to the target EFR32BG22 using the
Serial Wire Debug (SWD) interface. The debugger allows the user to download code and debug applications running in the target
EFR32BG22. Additionally, it also provides a VCOM port to the host computer that is connected to the target device's serial port, for
general purpose communication between the running application and the host computer. The Packet Trace Interface (PTI) is also sup-
ported by the on-board debugger which offers invaluable debug information about transmitted and received packets in wireless links.
The on-board debugger is accessible through the USB Micro-B connector.
An external debugger can be used instead of the on-board debugger by connecting it to the Mini Simplicity Connector. This allows ad-
vanced debugging features as described in section 4.2 External Debugger. When using an external debugger it is very important to
make sure that there is no power source present on the Thunderboard EFR32BG22, as the external debugger might source a voltage
on the target power domain (VMCU).
Important: When connecting an external debugger that sources voltage to the VMCU net, the USB cable and battery must be re-
moved from the Thunderboard EFR32BG22. Failure to do so will create power conflicts.
The figure below shows the possible debug options.
Figure 4.1. Thunderboard EFR32BG22 Debugging Possibilities
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Debugging
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