Silicon Laboratories UG524 User manual

UG524: xG24 Dev Kit User's Guide
The xG24 Dev Kit is a low-cost, small form factor development
and evaluation platform for the EFR32MG24 Wireless Gecko Sys-
tem-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 xG24 Dev Kit is an ideal
platform for developing energy-friendly connected IoT devices.
The xG24 Dev Kit ships with a Bluetooth demo that works with a cloud-connected smart-
phone app, showcasing easy collection of environmental and motion sensor data.
A built-in SEGGER J-Link debugger ensures easy debugging through the USB Micro-B
connector.
TARGET DEVICE
• EFR32 Wireless Gecko System-on-Chip
(EFR32MG24B310F1536IM48-B)
•High-performance 2.4 GHz radio
• 32-bit ARM® Cortex®-M33 with 78.0 MHz
maximum operating frequency
• 1536 flash and 256 kB RAM
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
• MEMS stereo microphones
• Pressure sensor
• 32 Mbit flash for OTA programming and
data logging
• RGB LED and two push buttons
• Precise voltage reference and dedicated
U.FL connector for ADC measurements
• 20-pin 2.54 mm breakout pads
• Qwiic® connector
• 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
• External battery connector
SOFTWARE SUPPORT
• Simplicity Studio™
silabs.com | Building a more connected world. Copyright © 2022 by Silicon Laboratories Rev. 0.1

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 EFR32MG24 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 ICS-43434 MEMS Stereo Microphones ....................13
3.4.4 ICM-20689 6-Axis Inertial Sensor ......................14
3.4.5 VEML6035 Ambient Light Sensor ......................15
3.4.6 BMP384 Barometric Pressure Sensor .....................15
3.4.7 External Memory ............................16
3.4.8 Push Buttons and RGB LED ........................16
3.4.9 Precise ADC Voltage Reference ......................16
3.4.10 IADC U.FL Connector..........................17
3.5 On-board Debugger ............................17
3.6 Connectors ...............................18
3.6.1 Breakout Pads ............................19
3.6.2 Qwiic Connector ............................20
3.6.3 Mini Simplicity Connector .........................20
3.6.4 Debug USB Micro-B Connector .......................20
4. Debugging ...............................21
4.1 On-board Debugger ............................22
4.2 External Debugger.............................22
4.2.1 External Debugger Considerations ......................22
4.3 Virtual COM Port .............................23
5. Radio .................................24
5.1 RF Section ...............................24
5.1.1 RF Matching Description .........................24
5.1.2 RF Section Power Supply .........................24
5.1.3 RF Matching Bill of Materials ........................24
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5.1.4 Antenna ...............................25
5.1.5 Antenna Matching Bill of Materials ......................25
5.2 EMC Regulations for 2.4 GHz .........................26
5.2.1 ETSI EN 300-328 Emission Limits for the 2400-2483.5 MHz Band ...........26
5.2.2 FCC15.247 Emission Limits for the 2400-2483.5 MHz Band .............26
5.2.3 Applied Emission Limits .........................26
5.3 Relaxation with Modulated Carrier .......................26
5.4 Radiated Power Measurements ........................27
5.4.1 Maximum Radiated Power Measurement ...................27
5.4.2 Antenna Pattern Measurement .......................28
5.5 EMC Compliance Recommendations ......................30
5.5.1 Recommendations for 2.4 GHz ETSI EN 300-328 Compliance ............30
5.5.2 Recommendations for 2.4 GHz FCC 15.247 Compliance ..............30
6. Schematics, Assembly Drawings, and BOM ...................31
7. Kit Revision History and Errata .......................32
7.1 Revision History .............................32
7.2 Errata .................................32
8. Board Revision History and Errata ......................33
8.1 Revision History .............................33
8.2 Errata .................................33
9. Document Revision History .........................34
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1. Introduction
The xG24 Dev Kit (OPN: xG24-DK2601B) has been designed to inspire customers to make battery-operated IoT devices with the Sili-
con Labs EFR32MG24 Wireless Gecko System-on-Chip. The highlights of the board include five different environmental sensors, ster-
eo I2S microphones, and a dedicated ADC U.FL connector and precise voltage reference, all accessible to the EFR32MG24 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 xG24 Dev Kit 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, and the Packet Trace Interface (PTI) offers invaluable debug information about
transmitted and received packets in wireless links. Included on the board is a 32 Mbit serial flash that can be used for Over-The-Air
(OTA) firmware upgrade, or as a general purpose non-volatile memory. The xG24 Dev Kit 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 xG24 Dev Kit can be done using the 20 breakout pads which present peripherals from the
EFR32MG24 Wireless 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. The board also features a Qwiic connector which can be used to connect hardware from
the Qwiic Connect System through I2C.
1.1 Kit Contents
The following items are included in the box:
• 1x MG24 Dev Kit board (BRD2601B)
• 1x USB Type A to Micro-B cable
1.2 Getting Started
Detailed instructions for how to get started with your new xG24 Dev Kit can be found on the Silicon Labs web page:
silabs.com/development-tools
1.3 Hardware Content
The following key hardware elements are included on the xG24 Dev Kit:
• EFR32MG24 Wireless Gecko SoC with 78.0 MHz operating frequency, 1536 kB flash, and 256 kB RAM
• 2.4 GHz ceramic antenna for wireless transmission
• Silicon Labs Si7021 relative humidity and temperature sensor
• Silicon Labs Si7210 hall effect sensor
• TDK InvenSense ICM-20689 6-axis inertial sensor
• Two ICS-43434 MEMS microphones
• Bosch Sensortec BMP384 barometric pressure sensor
• Ambient light sensor (VEML6035)
• Macronix ultra low power 32 Mbit SPI flash (MX25R3235F)
• RGB LED and two push buttons
• U.FL connector and precise external voltage reference for ADC measurements
• 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
• Qwiic connector for connecting external hardware from the Qwiic Connect System
• Reset button
• Automatic switchover between USB and battery power
• CR2032 coin cell holder and external battery connector
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Introduction
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1.4 Kit Hardware Layout
xG24 Dev Kit layout is shown below.
Top View Bottom View
Push Buttons
30.4 mm
51.0 mm
Reset Button
20-pin EXP-header
Breakout Pads
U.FL (ADC)
Connector
6-axis
Inertial Sensor
qwiic Header
USB Micro-B Connector
- Virtual COM port
- Debug access
- Packet trace
Hall Effect
Sensor
Humidity and
Temperature Sensor
Mini Simplicity
Connector
Pressure
Sensor
Ambient
Light & UV
Sensor
EFR32MG24
Wireless Gecko
2.4 GHz
Chip Antenna
On-board USB
J-Link Debugger
External
Battery Connector
CR2032 Coin Cell
Holder
Left I2S
Microphone
Right I2S
Microphone
RGB LED
Figure 1.1. xG24 Dev Kit Hardware Layout
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Introduction
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2. Specifications
2.1 Recommended Operating Conditions
Parameter Symbol Min Typ Max Unit
USB Supply Input Voltage VUSB — 5.0 — V
Battery Supply Input Voltage VVBAT 1.9 3.0 3.6 V
Supply Input Voltage (VMCU supplied externally)1,2,3 VVMCU 1.9 3.3 3.6 V
Operating Temperature TOP — 25 — ˚C
Note:
1. Brightness of the RGB LED will vary with the supply voltage. Due to manufacturing tolerances, functionality is not guaranteed
over the entire working range.
2. To optimize efficiency, EFR32MG24's internal DC-DC converter should be set in BYPASS mode when the input voltage ap-
proaches the output voltage, typically for supply voltages lower than 2.2 V. More details are found in EFR32MG24's data sheet.
3. Not recommended for use with rechargeable Lithium batteries. Most Li-Ion and Li-Po cells exceed 3.6 V when fully charged.
UG524: xG24 Dev Kit User's Guide
Specifications
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2.2 Current Consumption
The operating current of the board greatly depends on the application. The table below attempts to give some indication of how different
features of the board contribute to the overall power consumption. Note that the numbers are taken from the data sheets for the devi-
ces. For a full overview of the conditions that apply for a specific number from a data sheet, the reader is encouraged to read the specif-
ic data sheet.
Table 2.1. Current Consumption
Parameter Symbol Condition Typ Unit
EFR32 Current Consump-
tion1
IEFR32 MCU current consumption in EM0 mode with all peripher-
als disabled (DC-DC converter at 3.0 V input and 1.8 V
output, 39 MHz crystal, CPU running Prime from flash at
25 ˚C)
33.9 µA/MHz
EM4, no BURTC, no LF oscillator 0.25 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 = 39 MHz, 1Mbit/s, 2GFSK, f = 2.4 GHz, VSCALE1
at 25 ˚C)
4.4 mA
Radio system current consumption in transmit mode (DC-
DC converter at 3.0 V input and 1.8 V output, MCU in
EM1P and all MCU peripherals disabled, HCLK = 39 MHz,
f = 2.4 GHz, CW, 10 dBm output power, VSCALE1 at 25
˚C)
20 mA
RH/Temp Sensor Current
Consumption 2
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 Sensor Current
Consumption 3
ISi7210 Sleep mode at 3.3 V 50 µA
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-
sumption4,5
IMIC Sleep mode, fs less than 3.125 kHz 12 µA
Performance mode (VDD = 1.8 V) 490 µA
IMU Current Consumption 6IIMU Full-chip sleep mode at 1.8 V supply 6 µA
Gyroscope + Accelerometer 6-Axis low power mode, 100
Hz update rate at 1.8 V supply
1.9 mA
External Flash Current Con-
sumption 7
IMX25R3235F Deep Power-down at 1.8 V supply 7 nA
Standy at 1.8 V supply 5 µA
Program current (PP) at 1.8 V supply 3.5 mA
Ambient Light Sensor Cur-
rent Consumption 8
IVEML6035 Shutdown at 1.8 V supply 0.5 µA
Operation mode at 1.8 V supply (ALS only) 170 µA
Pressure Sensor Current
Consumption 9
IBMP384 Sleep current 2 µA
Peak current during pressure measurement 700 µA
Precise Voltage Reference IADC_VREF Enabled at 3.3 V supply 127 µA
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Specifications
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Parameter Symbol Condition Typ Unit
On-board Debugger Sleep
Current Consumption 10
IDBG On-board debugger current consumption when USB cable
is not inserted (EFM32GG12 EM4S mode current con-
sumption)
80 nA
1 From EFR32MG24 Wireless Gecko SoC data sheet
2 From Si7021-A20 data sheet
3 From Si7210 data sheet
4 From ICS-43434 data sheet
5 Per microphone
6 From ICM-20689 data sheet
7 From MX25R3235F data sheet
8 From VEML6035 data sheet
9 From BMP384 data sheet
10 From EFM32GG12 data sheet
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Specifications
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3. Hardware
The core of the xG24 Dev Kit is the EFR32MG24 Wireless Gecko System-on-Chip. The board also contains several peripherals con-
nected to the EFR32MG24. Refer to section 1.4 Kit Hardware Layout for placement and layout of the hardware components.
3.1 Block Diagram
An overview of the xG24 Dev Kit is illustrated in the figure below.
Memory
Sensors
ADC
Radio
Device Connectivity
Debugging
J-Link
Debugger
USB Micro-B
Connector
2.4 GHz
Antenna
32 Mbit
MX25R
Buttons and LED
EFR32MG24
Wireless SoC
Breakout Pads
(EXP-Header pinout)
Si7021 Si7210
VEML6035
Temperature
& Humidity
Sensor
Ambient
Light
Sensor
Hall Effect
Sensor
ICS-43434 ICM-20689
2x I2S
Microphones
6-axis Inertial
Sensor
BMP384
Pressure
Sensor
User Buttons
& RGB LED
Mini-Simplicity
Connector
Serial Flash
2.4 GHz
Antenna
SMA
Connector
Voltage
Reference
2.4 GHz
Antenna
SMA
Connector
U.FL
Connector
Qwiic
Connector
Figure 3.1. Kit Block Diagram
UG524: xG24 Dev Kit 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 (CR2032 battery or external battery connected through 2-pin battery header)
• 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
3V3
VMCU
Battery
EFR32MG24
Wireless SoC
Peripherals
Peripherals
Peripherals
Peripherals
Mini Simplicity
Connector
Figure 3.2. xG24 Dev Kit Power Architecture
Power is normally applied either through the USB cable or a CR2032 battery. A 2-pin 1.25 mm pitch battery connector for external bat-
teries is also available as an alternative to a CR2032 battery. When the USB cable is connected, VBUS is regulated down to 3.3 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. There must be no other power sources present on the kit as power is
injected directly to the VMCU net. It is important to follow this recommendation to avoid power conflicts and backfeeding the battery.
Powering the xG24 Dev Kit through the Mini Simplicity connector allows current measurements using the Advanced Energy 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. xG24 Dev Kit Power Options
Supply Mode Typical Input Voltage VMCU Source 3V3 5V
USB power 5.0 V On-board regulator On-board regulator USB VBUS
Battery 3.0 V Battery voltage Disconnected No voltage present
Mini Simplicity 3.3 V Debugger dependent Disconnected No voltage present
3.3 EFR32MG24 Reset
The EFR32MG24 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.
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3.4 Peripherals
The xG24 Dev Kit contains a set of peripherals that can be accessed from the EFR32MG24. All the peripherals have enable 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 minuscule
amount of power. This allows for the lowest possible power consumption in every application. The following peripherals are accessible
to the EFR32MG24:
• Silicon Labs Si7021 relative humidity & temperature sensor
• Silicon Labs Si7210 hall effect sensor
• 2x TDK InvenSense ICS-43434 MEMS microphones with I2S output
• TDK InvenSense ICM-20689 6-axis inertial measurement sensor
• Vishay VEML6035 ambient light sensor
• Bosch BMP384 pressure sensor with internal temperature sensor
• Macronix MX25R3235F ultra-low power 32 Mbit SPI flash
• RGB LED and two push buttons
• External precise voltage reference for the EFR32 IADC
• U.FL connector for the EFR32 IADC
The figure below gives an overview of the peripherals that are connected to the EFR32MG24. Note that some of the peripherals share
the same interface and enable signals. As the enable signals do not have external pull-down resistors on the board, it is recommended
to actively drive the signals either low or high in the application code to prevent the lines from floating.
PC10 (I2C0_SCL#14)
PC11 (I2C0_SDA#16)
EFR32MG24
ICM-20689
MX25R
VMCU
Si7021 VEML6035
2x ICS-43434
Si7210 BMP384
VMCU
I2C
I2S
SENSOR ENABLE
VMCU
VMCU
MIC ENABLE
ADC VREF ENABLE
SPI IMU CS
SPI
VMCU
SPI FLASH CS
IMU INTERRUPT
32 Mbit
Flash
3
2
2
3
Buttons RGB LED
GPIO GPIO ADC
VREF
U.FL Connector
3
Voltage Reference
Figure 3.3. Peripherals
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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 xG24 Dev Kit, the Si7021 is connected through a switch. The switch must therefore be enabled by setting PC09 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 EFR32MG24 I2C
bus. The application code should always drive the PC09 signal either high or low to prevent it from floating. The figure below shows
how the Si7021 is connected to the EFR32MG24.
Si7021
Temperature
& Humidity
Sensor
VMCU
EFR32MG24
PC04
PC05
PC09
VDD_SENSOR
I2C_SCL
I2C_SDA
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 xG24 Dev Kit, the Si7210 is connected through a switch. The switch must therefore be enabled by setting PC09 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 EFR32MG24 I2C
bus. The application code should always drive the PC09 signal either high or low to prevent it from floating. The figure below shows
how the Si7210 is connected to the EFR32MG24.
VMCU
EFR32MG24
PC04
PC05
PC09
VDD_SENSOR
I2C_SCL
I2C_SDA
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
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3.4.3 ICS-43434 MEMS Stereo Microphones
The ICS-43434 microphones are omnidirectional MEMS microphones with a wideband frequency response and a digital I2S output. The
microphones include a MEMS sensor, signal conditioning, ADC, filters, and different operating modes. The ICS-43434 is a bottom port
microphone, and it is placed on the bottom side of xG24 Dev Kit with acoustic ventilation holes going through to the top side. These
holes let sound waves into the microphone package.
On xG24 Dev Kit, the ICS-43434 microphones are connected through a switch. The switch must therefore be enabled by setting PC08
high before it can be used by the application. This enables power to the microphones and connects the I2S lines used for the sensor to
the EFR32MG24. The application code should always drive the PC08 signal either high or low to prevent it from floating. The figure
below shows how the ICS-43434 microphones are connected to the EFR32MG24.
VMCU
ICS-43434
I2S
Microphone (R)
ICS-43434
I2S
Microphone (L)
EFR32MG24
PD03
PD04
PD05
PC08
VDD_MIC
I2S_SCK
I2S_WS
I2S_SD
MIC_ENABLE
MIC_I2S_SCK
MIC_I2S_SD
MIC_I2S_WS VDD_MIC
VDD_MIC
0: Sensor is not powered
1: Sensor is powered
Figure 3.6. ICS-43434 MEMS Microphones
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3.4.4 ICM-20689 6-Axis Inertial Sensor
The ICM-20689 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 xG24 Dev Kit, the ICM-20689 is connected through a switch. The switch must be enabled by setting PC09 high before it can be
used by the application. This enables power to the ICM-20689 and connects the SPI lines used for the sensor to the EFR32MG24 SPI
bus. The application code should always drive the PC09 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 SPI CS line is
also exported on the breakout pads, so simultaneous SPI operation on the breakout pads and IMU is not possible unless an alternative
pin is used for SPI CS on the breakout pads. The figure below shows how the ICM-20689 is connected to the EFR32MG24.
VMCU
EFR32MG24
PC01
PC03
PC09
SPI_SCLK
SPI_COPI
SENSOR_ENABLE
IMU_SPI_SCLK
IMU_SPI_COPI
0: Sensor is not powered
1: Sensor is powered
ICM-20689
6-axis Intertial
Sensor
SPI_CIPO
PC02 IMU_SPI_CIPO
IMU_SPI_CS
VDD_SENSOR
IMU_INT
PB01 (EM4WU3)
SPI_CS
PA07
Figure 3.7. ICM-20689 6-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 3.8. xG24 Dev Kit Spatial Orientation
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3.4.5 VEML6035 Ambient Light Sensor
The VEML6035 is an ambient light sensor with I2C digital interface.
On xG24 Dev Kit, the VEML6035 is connected through a switch. The switch must therefore be enabled by setting PC09 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
EFR32MG24 I2C bus. The I2C lines are shared with other on-board I2C peripherals. The application code should always drive the PC09
signal either high or low to prevent it from floating. The I2C bus is shared with the Qwiic Connector and is also exported on the breakout
pads. The figure below shows how the VEML6035 is connected to the EFR32MG24.
VMCU
EFR32MG24
PC04
PC05
PC09
VDD_SENSOR
I2C_SCL
I2C_SDA
SENSOR_ENABLE
SENSOR_I2C_SCL
SENSOR_I2C_SDA
0: Sensor is not powered
1: Sensor is powered
VEML6035
Ambient
Light Sensor
Figure 3.9. VEML6035 Ambient Light Sensor
3.4.6 BMP384 Barometric Pressure Sensor
The BMP384 is a combined absolute barometric pressure sensor and temperature sensor with a digital interface supporting both SPI
and I2C. No external sensing elements are needed, and the device has an integrated ADC and ASIC with built-in configurable IIR filter
to suppress noise. Selectable oversampling rates provide trade-off between low power and high resolution, and an option to skip either
temperature or pressure measurement is available in case one or the other is unnecessary.
On xG24 Dev Kit, the BMP384 is connected through a switch. The switch must therefore be enabled by setting PC09 high before it can
be used by the application. This enables power to the BMP384 and connects the I2C lines used for the sensor to the EFR32MG24 I2C
bus. The I2C lines are shared with other on-board I2C peripherals. The application code should always drive the PC09 signal either high
or low to prevent it from floating. The I2C bus is shared with the Qwiic Connector and is also exported on the breakout pads. The figure
below shows how the BMP384 is connected to the EFR32MG24.
VMCU
EFR32MG24
PC04
PC05
PC09
VDD_SENSOR
I2C_SCL
I2C_SDA
SENSOR_ENABLE
SENSOR_I2C_SCL
SENSOR_I2C_SDA
0: Sensor is not powered
1: Sensor is powered
BMP384
Ambient
Light Sensor
Figure 3.10. BMP384 Absolute Pressure Sensor
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3.4.7 External Memory
The xG24 Dev Kit includes a 32 Mbit Macronix SPI Flash that is connected directly to the EFR32MG24. The MX25R series are ultra-low
power serial flash devices, so there is no need for a separate enable switch to keep current consumption down. However, 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 7 nA to the current consumption. The figure below shows how the serial
flash is connected to the EFR32MG24.
EFR32MG24
Serial Flash
32 Mbit
MX25R
SPI_COPI
SPI_CIPO
FLASH_SPI_CS
VMCU
SPI_SCLK
PC01
PC03
PC02
PC00
Figure 3.11. Serial Flash
3.4.8 Push Buttons and RGB LED
The kit has two user push buttons marked BTN0 and BTN1. They are connected directly to the EFR32MG24 and are debounced by RC
filters with a time constant of 1 ms. The buttons are connected to pins PB02 and PB03.
The kit also features an RGB LED marked LED0, controlled by GPIO pins on the EFR32MG24. The LED is connected in an active-low
configuration, and each color can be PWM controlled using the EFR32MG24's TIMER peripherals to generate a wide variety of colors.
User Buttons
& RGB LED
EFR32MG24
LEDR
LEDG
BUTTON1
BUTTON0
PB02
PB03 (EM4WU4)
PD02
PA04
PB00 LEDB
Figure 3.12. Buttons and RGB LED
3.4.9 Precise ADC Voltage Reference
The xG24 Dev Kit includes a high precision voltage reference based on the ADR1581, which features an initial accuracy of 0.12 % (1
mV) and low temperature drift. The voltage reference, when enabled, provides a low-noise 1.25 V external reference input to the
EFR32MG24 IADC, enabling optimal measurement performance.
On the xG24 Dev Kit, the voltage reference is connected through a switch. The switch must therefore be enabled by setting PA00 high
before it can be used by the IADC. The application code should always drive the PA00 signal either high or low to prevent it from float-
ing. The figure below shows how the voltage reference is connected to the EFR32MG24.
VMCU
ADC_VREF
EFR32MG24
VREFP
PA00
V_ADC
ADC_VREF_ENABLE
0: Reference is not enabled
1: Reference is enabled
ADR1581
Voltage
Reference
Figure 3.13. Precise ADC Voltage Reference
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3.4.10 IADC U.FL Connector
The kit features a U.FL connector which is connected to the EFR32MG24 IADC through one of the dedicated ADC input pins (AIN0) in
a single-ended configuration. The dedicated ADC inputs facilitate optimal connections between external signals and the IADC.
A charge bucket filter has been placed at the ADC input, which helps improve sampling performance and measurement accuracy at
high sampling speeds, and provides some anti-aliasing for high-frequent signals. For information about the IADC performance and con-
figuration, refer to the EFR32MG24 data sheet.
EFR32MG24
AIN0
U.FL
Connector
Figure 3.14. U.FL Connector
3.5 On-board Debugger
The xG24 Dev Kit contains a microcontroller separate from the EFR32MG24 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 EFR32MG24 device and the on-board debugger. The figure also shows the
Mini Simplicity Connector, and how this is connected to the same I/O pins.
Refer to section 4. Debugging for more details on debugging.
Mini Simplicity
Connector
EFR32MG
EFR32MG24
PA01 (GPIO.SWCLK)
PA02 (GPIO.SWDIO)
PA03 (GPIO.SWV)
PA05
PA06
DBG_VCOM_TX
DBG_VCOM_RX
DBG_SWCLK
DBG_SWDIO
DBG_SWO
On-Board
J-Link
Debugger
Host
PC USB
DBG_PTI_DATA PC06 (FRC.DOUT)
PC07 (FRC.DFRAME)
DBG_PTI_FRAME
DBG_RESET RESETn
Figure 3.15. On-Board Debugger Connections
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3.6 Connectors
The xG24 Dev Kit features 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-sections.
EXP2 - VMCU
EXP4 - SPI_COPI - PC03
EXP18 - 5V
EXP20 - 3V3
EXP6 - SPI_CIPO - PC02
EXP8 - SPI_SCLK - PC01
EXP10 - SPI_CS - PA07
EXP12 - UART_TX - PA05
EXP14 - UART_RX - PA06
EXP16 - I2C_SDA - PC05
I2C_SDA - PC05
GND - EXP1
PB02 - GPIO - EXP3
AIN3 - ADC - EXP5
AIN2 - ADC - EXP7
PB00 - GPIO - EXP9
PB03 - GPIO - EXP11
PD02 - GPIO - EXP13
PC04 - I2C_SCL - EXP15
BOARD_ID_SCL - EXP17
BOARD_ID_SDA - EXP19
Expansion Header
Breakout Pads
VMCU
VMCU
RST
PA05 - VCOM_TX
PA02 - SWDIO
PC07 - PTI_FRAME
GND
GND
VCOM_RX - PA06
I2C_SCL - PC04
SWO - PA03
SWCLK - PA01
PTI_DATA - PC06
Mini Simplicity
Connector
USB Micro-B
Connector
Mini-Simplicity
Connector
qwiic
Connector
qwiic
Connector
Pin 1
P1
X1
1
3
5
7
9
11
13
15
17
19
2
4
6
8
10
12
14
16
18
20
Figure 3.16. xG24 Dev Kit Connectors
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3.6.1 Breakout Pads
Twenty 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 EFR32MG24's features. Additionally, the VMCU (main power rail), 3V3 (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 xG24 Dev Kit. 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
Right Side Breakout Pins
2 VMCU EFR32MG24 voltage domain, included in AEM measurements.
4 PC03 SPI_COPI IMU & Flash
6 PC02 SPI_CIPO IMU & Flash
8 PC01 SPI_SCLK IMU & Flash
10 PA07 SPI_CS IMU_SPI_CS (when SENSOR_ENABLE = 1)
12 PA05 UART_TX VCOM & Mini Simplicity
14 PA06 UART_RX VCOM & Mini Simplicity
16 PC05 I2C_SDA Qwiic I2C bus
18 5V Board USB voltage
20 3V3 Board controller supply
Left Side Breakout Pins
1 GND Ground
3 PB02 GPIO BTN0
5 AIN3 ADC Negative Input
7 AIN2 ADC Positive Input
9 PB00 GPIO LEDB
11 PB03 GPIO BTN1
13 PD02 GPIO LEDR
15 PC04 I2C_SCL Qwiic I2C bus
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 Qwiic Connector
The xG24 Dev Kit features a Qwiic connector compatible with Qwiic Connect System hardware. The Qwiic connector provides an easy
way to expand the functionality of the xG24 Dev Kit with sensors, LCDs, and other peripherals over the I2C interface. The Qwiic con-
nector is a 4-pin polarized JST connector, which ensures the cable is inserted the right way.
Qwiic Connect System hardware is daisy chain-able as long as each I2C device in the chain has a unique I2C address.
Note: The Qwiic I2C lines are shared with the on-board I2C sensors, and are also exposed on the breakout pads.
The table below gives an overview of the Qwiic connections to the EFR32MG24.
Table 3.3. Qwiic Connector Pinout
Qwiic Pin Connection Shared Feature
Ground GND
3.3V VMCU
SDA PC05 Breakout pads, I2C sensors
SCL PC04 Breakout pads, I2C sensors
3.6.3 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 one of the Silicon Labs Wireless mainboards. See section 4.2 External Debugger for more details. The pinout of the connector on
the board is described in the table below with the names being referenced from the EFR32MG24.
Table 3.4. Mini Simplicity Connector Pin Descriptions
Pin number Function Connection Description
1 AEM VMCU Target voltage on the debugged application. May be supplied and
monitored by the AEM on an external debugger.
2 GND GND Ground.
3 RST RESET EFR32MG24 reset.
4 VCOM_RX PA06 Virtual COM Rx
5 VCOM_TX PA05 Virtual COM Tx
6 SWO PA03 Serial Wire Output
7 SWDIO PA02 Serial Wire Data
8 SWCLK PA01 Serial Wire Clock
9 PTI_FRAME PC07 Packet Trace Frame
10 PTI_DATA PC06 Packet Trace Data
3.6.4 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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