UG309: Thunderboard Sense 2 User's
Guide
The Thunderboard™ Sense 2 is the ultimate multi-sensor, multiprotocol cloud inspiration kit.
The board is a small and cost-effecitve, feature-rich prototype and development platform based on the EFR32™ Mighty Gecko Wireless System-on-Chip. The Thunderboard Sense 2 is an ideal platform for developing energy-friendly connected IoT devices. This is a true multiprotocol capable kit, supporting proprietary stacks and standard
protocols such as Zigbee, Thread and Bluetooth® low energy.
The Thunderboard Sense 2 ships with a ready-to-use Bluetooth demo that works with a
cloud connected smartphone app, showcasing easy collection of environmental and
motion sensor data.
A built in SEGGER J-Link debugger ensures easy customization and development.
KEY POINTS
• EFR32MG12 Mighty Gecko Wireless SoC
with 38.4 MHz operating frequency, 1024
kB flash and 256 kB RAM
• 2.4 GHz ceramic chip antenna
• Fine-grained power-control for ultra-lowpower operation
• Seven sensors and four high brightness
controllable RGB LEDs
• User LEDs/pushbuttons
• 8-Mbit flash for OTA programming and
data logging
• SEGGER J-Link on-board debugger
• Virtual COM port
• Packet Trace
• Mini Simplicity connector for connection
to an external Silicon Labs debugger
• 20-pin 2.54 mm breakout pads
• Power sources include USB, coin cell and
external batteries
ON-BOARD SENSORS
• Relative humidity and temperature sensor
• UV index and ambient light sensor
• Hall effect sensor
• Indoor air quality gas sensor
• 6-axis inertial sensor
• Barometric pressure sensor
• MEMS microphone
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SOFTWARE SUPPORT
• Simplicity Studio™
ORDERING INFORMATION
• SLTB004A
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Table of Contents
1. Introduction ................................4
1.1 Kit Contents ...............................4
1.2 Hardware Content .............................5
1.3 Kit Hardware Layout ............................5
2. Specifications ...............................6
2.1 Absolute Maximum Ratings..........................6
2.2 Recommended Operating Conditions ......................6
2.3 Current Consumption ............................7
3. Hardware .................................9
3.1 Block Diagram ..............................9
3.2 Power Supply ..............................10
3.3 EFR32MG12 Reset ............................11
3.4 Sensors and RGB LEDs ...........................11
3.4.1 Si7021 Relative Humidity and Temperature Sensor ................12
3.4.2 Si1133 UV Index and Ambient Light Sensor...................12
3.4.3 BMP280 Barometric Pressure Sensor .....................13
3.4.4 Si7210 Hall Effect Sensor .........................13
3.4.5 CCS811 Indoor Air Quality Gas Sensor ....................14
3.4.6 ICM-20648 6-Axis Inertial Sensor ......................15
3.4.7 ICS-43434 MEMS Microphone .......................16
3.4.8 RGB LEDs ..............................17
3.5 Push Buttons and RG LED ..........................18
3.6 Memory ................................18
3.7 On-board Debugger ............................19
3.8 Connectors ...............................20
3.8.1 Breakout Pads ............................21
3.8.2 Mini Simplicity Connector .........................22
3.8.3 USB Micro-B Connector .........................22
3.8.4 Battery Connector ...........................22
4. Debugging ...............................23
4.1 On-board Debugger Considerations .......................23
4.2 Virtual COM Port .............................24
4.3 Mini Simplicity Connector ..........................24
5. Radio .................................25
5.1 RF Section ...............................25
5.1.1 Description of the RF Matching .......................25
5.1.2 RF Section Power Supply .........................25
5.1.3 RF Matching Bill of Materials ........................25
5.1.4 Antenna ...............................26
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5.1.5 Antenna Matching Bill of Materials ......................26
5.2 EMC Regulations for 2.4 GHz .........................27
5.2.1 ETSI EN 300-328 Emission Limits for the 2400-2483.5 MHz Band ...........27
5.2.2 FCC15.247 Emission Limits for the 2400-2483.5 MHz Band .............27
5.2.3 Applied Emission Limits .........................27
5.3 Radiated Power Measurements ........................28
5.3.1 Maximum Radiated Power Measurement ...................28
5.3.2 Antenna Pattern Measurement .......................29
5.4 EMC Compliance Recommendations ......................31
5.4.1 Recommendations for 2.4 GHz ETSI EN 300-328 Compliance ............31
5.4.2 Recommendations for 2.4 GHz FCC 15.247 Compliance ..............31
6. Schematics, Assembly Drawings and BOM ...................32
7. Kit Revision History and Errata .......................33
7.1 Revision History .............................33
8. Board Revision History and Errata ......................34
8.1 Revision History .............................34
8.2 Errata .................................34
9. Document Revision History .........................35
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UG309: Thunderboard Sense 2 User's Guide
Introduction
1. Introduction
The Thunderboard Sense 2 has been designed to inspire customers to make battery operated IoT devices with the Silicon Labs
EFR32MG12 Mighty Gecko Wireless System-on-Chip. The highlights of the board include seven different environmental sensors and
four high brightness RGB LEDs accessible to the EFR32MG12 wireless MCU. The sensors and LEDs have been grouped into power
domains that can be turned on and off by the application code as needed. By default, the board starts up in the lowest power operating
mode, with all sensors disabled.
Programming the Thunderboard Sense 2 is easily done using a USB Micro-B cable and the on-board J-Link debugger. A USB virtual
COM port provides a serial connection to the target application. 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 Sense 2 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 Connector using an external Silicon Labs debugger. See AN958: Debugging and Programming Interfaces for Custom Designs for more information about debugging and programming interfaces that can be used with Silicon Labs' starter kits.
Connecting external hardware to the Thunderboard Sense 2 can be done using the 20 breakout pads which present peripherals from
the EFR32MG12 Mighty Gecko such as I2C, SPI, UART and GPIOs. The breakout pads follow the same pinout as the expansion head-
ers (EXP) on other Silicon Labs Starter Kits.
Figure 1.1. Thunderboard Sense 2
1.1 Kit Contents
The following items are included in the box:
• 1x Thunderboard Sense 2 board (BRD4166A)
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Top View
Bottom View
RGB LED 0
RGB LED 2
Push Button 0
Push Button 1
30 mm
45 mm
Reset Button
Acoustic hole
RGB LED 1
BMP280 Pressure
Sensor
CCS811 Indoor
Air Quality Sensor
20-pin EXP-header
Breakout Pads
ICM-20648 6-axis
Inertial Sensor
USB Micro-B Connector
- Virtual COM port
- Debug access
Si7210 Hall Effect
Sensor
Si7021 Humidity and
Temperature Sensor
Mini-Simplicity
Connector
Si1133 Ambient
Light & UV
Sensor
EFR32MG12
Mighty Gecko
2.4 GHz
Chip Antenna
ICS-43434 MEMS
Microphone
On-board USB
J-Link Debugger
External Battery
Connector
CR2032 Coin Cell
Holder
RGB LED 3
UG309: Thunderboard Sense 2 User's Guide
1.2 Hardware Content
The following key hardware elements are included on the Thunderboard Sense 2:
• EFR32MG12 Mighty Gecko Wireless SoC with 38.4 MHz operating frequency, 1024 kB flash and 256 kB RAM
• 2.4 GHz ceramic antenna for wireless transmission
• Silicon Labs Si7021 relative humidity and temperature sensor
• Silicon Labs Si1133 UV index and ambient light sensor
• Silicon Labs Si7210 hall effect sensor
• Bosch Sensortec BMP280 barometric pressure sensor
• ams CCS811 indoor air quality gas sensor
• TDK InvenSense ICM-20648 6-axis inertial sensor
• TDK InvenSense ICS-43434 MEMS microphone
• Four high brightness RGB LEDs from Broadcom Limited (ASMT-YTB7-0AA02)
• One bi-color LED and two push buttons
• Power enable signals for fine grained power-control
• Macronix ultra-low-power 8-Mbit SPI flash (MX25R8035F)
• On-board SEGGER J-Link debugger for easy programming and debugging, which includes a USB virtual COM port
• 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 and external battery connector
Introduction
1.3 Kit Hardware Layout
The layout of the Thunderboard Sense 2 is shown below.
Figure 1.2. Thunderboard Sense 2 Hardware Layout
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UG309: Thunderboard Sense 2 User's Guide
Specifications
2. Specifications
2.1 Absolute Maximum Ratings
Parameter Symbol Min Typ Max Unit
USB Input Voltage V
Battery Input Voltage (VMCU) V
LDO output current I
USB-MAX
BAT-MAX
VREG-LOAD
Voltage on any I/O breakout pad V
Current per I/O pin (sink) I
Current per I/O pin (source) I
Current for all I/O pins (sink) I
Current for all I/O pins (source) I
IOALLMAX
IOALLMAX
ESD Susceptibility HBM (Human Body Model) V
DIGPIN
IOMAX
IOMAX
ESD
0 +5.5 V
0 +3.6 V
300 mA
-0.3 VMCU+0.3 V
50 mA
50 mA
200 mA
200 mA
2 kV
2.2 Recommended Operating Conditions
Parameter Symbol Min Typ Max Unit
USB Supply Input Voltage V
Battery Supply Input Voltage V
Supply Input Voltage (VMCU supplied externally) V
Operating Temperature
1
USB
VBAT
VMCU
T
OP
+4.5 +5.0 +5.5 V
+2.0 +3.3 V
+2.0 +3.3 V
-35 85 ˚C
1 Using the CCS811 gas sensor limits the operating temperature range from -5 to 50 ˚C.
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UG309: Thunderboard Sense 2 User's Guide
Specifications
2.3 Current Consumption
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. The table below attempts to give some indication of how different features of the board contribute to the overall power consumption. Note that some numbers are measured values, while others are taken from the data sheets for the devices. For a full overview of the conditions that apply
for a specific number from a data sheet, the reader is encouraged to read the specific data sheet.
Table 2.1. Current Consumption
Parameter Symbol Condition Min Typ Max Unit
EFR32 Current Consumption
UV/ALS Current Consumption
1
2
I
EFR32
I
Si1133
EFR32 in EM0 Active mode. 3.4 mA
Radio in receive mode. 10 mA
Radio transmitter active @ 8 dBm 26 mA
Standby 0.125 µA
ADC Conversion in Progress 0.525 µA
RH/Temp Sensor Current Consumption
Barometric Pressure Sensor Current Consumption
Microphone Current Consumption
CCS811 Current Consumption
IMU Current Consumption
4
5
6
7
Responding to commands and calculat-
4.5 mA
ing results
3
I
Si7021
Standby, -40 to +85˚C 0.06 0.62 µA
RH conversion in progress 150 180 µA
Temperature conversion in progress 90 120 µA
3.5 4.0 mA
2.8 4.2 µA
I
BMP280
Peak IDD during I2C operations
Sleep current 0.1 0.3 µA
1 Hz forced mode, pressure & temperature, lowest power
Peak current during pressure measure-
0.72 1.12 mA
ment
Current at temperature measurement 0.33 mA
I
Sleep mode current (fs<3.125 kHz) 12 20 uA
MIC
Supply current in high-performance mode
490 550 uA
with VDD = 1.8 V and no load
I
CCS811
Enabled, sleep mode at 1.8 V supply 19 µA
During measurement at 1.8 V supply 26 mA
Average over pulse cycle at 1.8 V supply 0.7 mA
I
Full-chip sleep mode at 1.8 V supply 8 µA
IMU
Gyroscope only, 102.3 Hz update rate at
1.23 mA
1.8 V supply
Accelerometer only, 102.3 Hz update
68.9 µA
rate at 1.8 V supply
Gyroscope + Accelerometer, 102.3 Hz
1.27 mA
update rate at 1.8 V supply
RGB LED Current Consumption
8
I
RGB
Power enabled, all LEDs off 65 µA
Additional current for each enabled LED 10 µA
Current per LED, all colors 100% duty cy-
29.9 mA
cle
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UG309: Thunderboard Sense 2 User's Guide
Specifications
Parameter Symbol Condition Min Typ Max Unit
On-board Debugger Current Consumption8I
DBG
1 From EFR32MG12 Mighty Gecko SoC data sheet
2 From Si1133 data sheet
3 From Si7021-A20 data sheet
4 From BMP280 data sheet
5 From ICS-43434 data sheet
6 From CCS811 data sheet
7 From ICM-20648 data sheet
8 Measured values
USB cable inserted, current sourced from
USB 5V
USB cable removed, current sourced
from VMCU rail.
29 mA
20 nA
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Memory
Si7021
CCS811
Si7210
Si1133
ICS-43434
ICM-20648
Sensors
Radio
Device Connectivity & Debugging
x4
BMP280
J-Link
Debugger
USB Micro-B
Connector
2.4 GHz
Antenna
8 Mbit
MX25R
Buttons and LEDs
EFR32MG12
Wireless SoC
Breakout Pads
(EXP-Header pinout)
RGB LEDs
Temperature
& Humidity
Sensor
Ambient
Light & UV
Sensor
Hall Effect
Sensor
MEMS
Microphone
6-axis Inertial
Sensor
Pressure
Sensor
Indoor
Air Quality
Sensor
RGB LEDs
User Buttons
& RG LED
Mini-Simplicity
Connector
Serial Flash
UG309: Thunderboard Sense 2 User's Guide
Hardware
3. Hardware
The core of the Thunderboard Sense 2 is the EFR32MG12 Mighty Gecko Wireless System-on-Chip. The board also contains a multitude of sensors, including various environmental sensors and a motion sensor, all connected to the EFR32MG12. The user interface
components include push buttons, a bi-colour LED, and four high brightness RGB LEDs.
The key aspects of the hardware will be explained in this chapter, while in-depth information on the EFR32MG12 Mighty Gecko SoC
can be found in the EFR32MG12 data sheet and reference manual. For placement and layout of the hardware components the reader
is referred to section 1.3 Kit Hardware Layout.
3.1 Block Diagram
An overview of the Thunderboard Sense 2 is illustrated in the figure below.
Figure 3.1. Kit Block Diagram
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USB micro-B
LDO
5V0
IN
OUT
Automatic
Switchover
3V3
VMCU
Battery
EFR32MG12
Wireless SoC
Peripherals
Peripherals
Peripherals
Peripherals
Mini Simplicity
Connector
UG309: Thunderboard Sense 2 User's Guide
Hardware
3.2 Power Supply
There are several ways to power the kit. The options include battery, on-board LDO from USB and the Mini Simplicity connector. Figure
3.2 Thunderboard Sense 2 Power Options on page 10 shows the power options available on the kit and illustrates the main system
power architecture.
Figure 3.2. Thunderboard Sense 2 Power Options
In normal operation, power can be applied using either a USB cable connected to a power source, or a battery connected to one of the
battery connectors. The 5 V power net on the USB bus is regulated down to 3.3 V using a low-dropout regulator. An automatic switchover circuit switches the main system power from battery power to USB power when the USB cable is inserted, and prevents charging
of the battery.
Batteries can be connected to the Thunderboard Sense 2 using either the CR2032 coin cell holder or the external battery connector. A
CR2032 coin cell is sufficient for low-power operation that does not require high peak current. More demanding applications, such as
enabling the RGB LEDs at high intensities, might need a higher capacity external battery or USB power. Do not connect batteries to
both the CR2032 coin cell connector and the external battery connector simultaneously, as there are no protection mechanisms between the two battery connectors.
Important: Do not connect batteries to both the CR2032 coin cell holder and the external battery connector simultaneously.
A third option for powering the Thunderboard Sense 2 exists through the Mini Simplicity connector. Powering the Thunderboard Sense
2 through the Mini Simplicity connector with an external Silicon Labs debugger allows accurate current measurements using the Advanced Energy Monitoring (AEM) feature of the external debugger. This option requires that no other power sources are present on the
kit, as the power is injected directly to the VMCU net. Doing so will cause conflict between the two regulators and erroneous AEM
measurements. For more information about using the Mini Simplicity connector, refer to section 4.3 Mini Simplicity Connector.
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. For placement of the USB and battery connectors, the reader is referred
to section 1.3 Kit Hardware Layout.
Table 3.1. Thunderboard Sense 2 Power Options
Supply Mode VIN VMCU 3V3 5V0
USB power 4.5 - 5.5 V On-board regulator On-board regulator USB VBUS
CR2032 battery 2.0 - 3.3 V Battery voltage Turned off and isolated No voltage present
External battery 2.0 - 3.3 V Battery voltage Turned off and isolated No voltage present
Mini Simplicity 2.0 - 3.3 V Debugger dependent Turned off and isolated No voltage present
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PC10 (I2C0_SCL#14)
PC11 (I2C0_SDA#16)
EFR32MG
EFR32MG12
CCS811
ICM-20648
BMP280
Si7021
Si1133
Si7210
RGB LEDs
x4
ICS-43434
VMCU
IOVDD
ENV_SENSE_ENABLE
ENV_I2C
VMCU
UV_ALS_INT
VMCUVMCU VMCU
IMU_ENABLE
CCS811_ENABLE
HALL_ENABLE
IMU_SPI
IMU_INT
CCS811_I2C
CCS811_#WAKE
CCS811_INT
HALL_I2C
HALL_OUT1
Power
Power
Power
Power
MIC_ENABLE
Power
MIC_I2S
DC/DC
EN
VMCU
Power[3:0]
RGB_LED_ENABLE
LED_COM[3:0]
LED_RGB[R,G,B]
3.5 V
UG309: Thunderboard Sense 2 User's Guide
Hardware
3.3 EFR32MG12 Reset
The EFR32MG12 Wireless SoC 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.
3.4 Sensors and RGB LEDs
The Thunderboard Sense 2 contains seven different sensors and four high brightness RGB LEDs which can be accessed from the
EFR32MG12.
• Silicon Labs Si7021 relative humidity & temperature sensor
• Silicon Labs Si1133 UV index & ambient light sensor
• Silicon Labs Si7210 hall effect sensor
• Bosch Sensortec BMP280 barometric pressure sensor
• ams CCS811 indoor air quality gas sensor
• TDK InvenSense ICM-20648 6-axis inertial measurement sensor
• TDK InvenSense ICS-43434 MEMS microphone
• Four high brightness RGB LEDs from Broadcom Limited (ASMT-YTB7-0AA02)
All the sensors have enable signals which can be used to completely turn off sensors that are not in use. This allows for the lowest
possible power consumption in every application. Three of the environmental sensors have been grouped together and share the same
power supply enable signal, while the remaining sensors have individual enable signals. The dc-dc converter that powers the high
brightness RGB LEDs can be turned off when the LEDs are not in use, and each RGB LED have furthermore its own power supply
enable signal.
An overview of the connection and power topology of the sensors and RGB LEDs are given in the figure below.
Figure 3.3. Sensors and RGB LEDs
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