Silicon Labs BRD4185A Reference Manual
EFR32BG22 Direction Finding Radio
Board
BRD4185A Reference Manual
The BRD4185A Wireless Gecko Radio Board enables developers to develop RF-based
Real-Time Locationing Systems and applications, utilizing the protocol level support of
Angle of Arrival (AoA) and Angle of Departure (AoD) in Bluetooth 5. The board contains
a 2.4 GHz Wireless Gecko Wireless System-on-Chip, and an antenna array optimized
for accurate direction finding performance.
The BRD4185A Wireless Gecko Radio Board plugs into the Wireless Starter Kit Mainboard, which is included with the Wireless Gecko Starter Kit and gives access to debug
interface, Virtual COM port, packet trace, display, buttons, LEDs, and additional features
from expansion boards. With the supporting Simplicity Studio suite of tools, developers
can take advantage of graphical wireless application development and visual energy
profiling and optimization. The board also serves as an RF reference design for applications targeting Bluetooth 2.4 GHz AoA-based direction finding.
This document contains a brief introduction and description of the BRD4185A Radio
Board features, focusing on the RF sections and basic performance.
RADIO BOARD FEATURES
• Wireless SoC:
EFR32BG22C224F512IM40
•
CPU core: ARM® Cortex®-M33
• Flash memory: 512 kB
• RAM: 32 kB
• Operation frequency: 2.4 GHz
• Transmit power: 6 dBm
• Antenna array with PCB antennas
• UFL connector (optional)
• Crystals for LFXO and HFXO: 32.768 kHz
and 38.4 MHz
• 8 Mbit low-power serial flash for over-theair updates
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Table of Contents
1. Introduction ................................4
2. Radio Board Connector ...........................5
2.1 Introduction ...............................5
2.2 Radio Board Connector Pin Associations .....................5
3. Radio Board Block Summary .........................6
3.1 Introduction ...............................6
3.2 Radio Board Block Diagram .........................6
3.3 Radio Board Block Description ........................6
3.3.1 Wireless MCU.............................6
3.3.2 LF Crystal Oscillator (LFXO) ........................6
3.3.3 HF Crystal Oscillator (HFXO)........................6
3.3.4 Matching Network for 2.4 GHz .......................6
3.3.5 UFL Connector ............................7
3.3.6 Radio Board Connectors .........................7
3.3.7 2.4 GHz Antenna Array..........................7
3.3.8 Serial EEPROM ............................7
4. RF Section ................................8
4.1 Introduction ...............................8
4.2 Schematic of the RF Matching Network......................8
4.2.1 Description of the 2.4 GHz RF Matching ....................8
4.3 Bill of Materials for the 2.4 GHz Matching .....................8
4.4 Antenna Array ..............................8
5. Mechanical Details ............................ 10
6. EMC Compliance ..............................11
6.1 Introduction ...............................11
6.2 EMC Regulations for 2.4 GHz .........................11
6.2.1 ETSI EN 300-328 Emission Limits for the 2400-2483.5 MHz Band ...........11
6.2.2 FCC15.247 Emission Limits for the 2400-2483.5 MHz Band .............11
6.2.3 Applied Emission Limits for the 2.4 GHz Band ..................11
7. RF Performance ............................. 12
7.1 Conducted Power Measurements .......................12
7.1.1 Conducted Power Measurements with Unmodulated Carrier .............12
7.1.2 Conducted Power Measurements with Modulated Carrier ..............13
7.2 Radiated Power Measurements ........................14
7.2.1 Maximum Radiated Power Measurements ...................15
7.2.2 Antenna Pattern Measurements.......................15
8. EMC Compliance Recommendations ..................... 16
8.1 Recommendations for 2.4 GHz ETSI EN 300-328 Compliance ..............16
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8.2 Recommendations for 2.4 GHz FCC 15.247 Compliance ................16
9. Board Revision History .......................... 17
10. Errata................................. 18
11. Document Revision History ........................ 19
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BRD4185A Reference Manual
Introduction
1. Introduction
The EFR32™ Wireless Gecko Radio Boards provide a development platform (together with the Wireless Starter Kit Mainboard) for the
Silicon Labs EFR32 Wireless Gecko Wireless System-on-Chips and serve as reference designs for the matching network of the RF
interface.
The BRD4185A Radio Board is designed to operate in the 2400-2483.5 MHz band with the RF matching network optimized for operating at 6 dBm output power, and the on-board antenna array optimized for accurate direction finding perfromance.
To develop and/or evaluate the EFR32 Wireless Gecko, the BRD4185A Radio Board can be connected to the Wireless Starter Kit Mainboard to get access to debug interface, Virtual COM port, packet trace, display, buttons, LEDs, and additional features from expansion
boards, and also to evaluate the performance of the RF interface and the direction finding accuracy.
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GND
F9 / PA07 / VCOM_RTS
3v3
NC / P36
P200
Upper Row
NC / P38
NC / P40
DBG_TDO_SWO / PA03 / P42
NC / P44
DBG_TMS_SWDIO / PA02 / F0
VCOM_ENABLE / DISP_ENABLE / PB04 / F14
UIF_BUTTON0 / PB00 / F12
UIF_LED0 / PB02 / F10
VCOM_CTS / PA08 / F8
DBG_RESET / #RESET / F4
DBG_TDO_SWO / PA03 / F2
DISP_MOSI / PC00 / F16
VCOM_TX / PA05 / F6
PTI_DATA / PD02 / F20
DISP_EXTCOMIN / PA00 / F18
USB_VBUS
5V
Board ID SCL
GND
Board ID SDA
USB_VREG
F7 / PA06 / VCOM_RX
F5 / PB04 / VCOM_ENABLE / DISP_ENABLE
F3 / PA04 / DBG_TDI*
F1 / PA01 / DBG_TCK_SWCLK
P45 / NC
P43 / NC
P41 / PA04 / DBG_TDI*
P39 / NC
P37 / NC
F11 / PB03 / UIF_LED1
F13 / PB01 / UIF_BUTTON1
F15 / PC02 / DISP_SCLK
F17 / PC03 / DISP_SCS
F19 / PD03 / PTI_SYNC
F21 / NC
GND
VMCU_IN
VCOM_CTS / PA08 / P0
P201
Lower Row
VCOM_RTS / PA07 / P2
UIF_BUTTON0 / PB00 / P4
UIF_BUTTON1 / PB01 / P6
GND
VRF_IN
P35 / PC07
P7 / PC03 / DISP_SCS
P5 / PC02 / DISP_SCLK
P3 / PC01
P1 / PC00 / DISP_MOSI
P33 / PC06
P31 / PC05
P29 / PC04
P27 / PD03 / PTI_SYNC
P25 / PD02 / PTI_DATA
P23 / NC
P21 / NC
P19 / NC
P17 / NC
P15 / PB04 / VCOM_ENABLE / DISP_ENABLE
P13 / NC
P11 / PA06 / VCOM_RX
P9 / PA05 / VCOM_TX
NC / P34
NC / P32
NC / P30
NC / P28
NC / P26
NC / P24
DBG_TDI* / PA04 / P22
DBG_TDO_SWO / PA03 / P20
DBG_TMS_SWDIO / PA02 / P18
DBG_TCK_SWCLK / PA01 / P16
DISP_EXTCOMIN / PA00 / P14
NC / P12
UIF_LED1 / PB03 / P10
UIF_LED0 / PB02 / P8
*Optional 0R resistor should be mounted to enable this connection. (Mutually exclusive with FLASH_SCS.)
BRD4185A Reference Manual
Radio Board Connector
2. Radio Board Connector
2.1 Introduction
The board-to-board connector scheme allows access to all EFR32BG22 GPIO pins as well as the RESETn signal. For more information
on the functions of the available pins, see the EFR32BG22 data sheet.
2.2 Radio Board Connector Pin Associations
The figure below shows the mapping between the connector and the EFR32BG22 pins and their function on the Wireless Starter Kit
Mainboard.
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Figure 2.1. BRD4185A Radio Board Connector Pin Mapping
3. Radio Board Block Summary
2.4 GHz RF
UFL
Connector
LF
Crystal
32.768k
HF
Crystal
38.4M
Radio
Board
Connectors
I2C
24AA024
Serial
EEPROM
Matching
Network &
Output
Selection
GPIO
UART
Debug
Packet Trace
AEM
I2C
SPI
2.4 GHz RF
EFR32
EFR32
Wireless SoC
8 Mbit
MX25R
Serial Flash
SPI
RF
Switches
GPIO
Antenna Array
2.4 GHz RF
2.4 GHz RF
3.1 Introduction
This section introduces the blocks of the BRD4185A Radio Board.
3.2 Radio Board Block Diagram
The block diagram of the BRD4185A Radio Board is shown in the figure below.
BRD4185A Reference Manual
Radio Board Block Summary
Figure 3.1. BRD4185A Block Diagram
3.3 Radio Board Block Description
3.3.1 Wireless MCU
The BRD4185A Wireless Gecko Radio Board incorporates an EFR32BG22C224F512IM40 Wireless System-on-Chip featuring 32-bit
Cortex®-M33 core, 512 kB of flash memory, 32 kB of RAM and a 2.4 GHz band transceiver with output power up to 6 dBm. For addi-
tional information on the EFR32BG22C224F512IM40, refer to the EFR32BG22 Data Sheet.
3.3.2 LF Crystal Oscillator (LFXO)
The BRD4185A Radio Board has a 32.768 kHz crystal mounted. For details regarding the crystal configuration, refer to application note
AN0016.2: Oscillator Design Considerations.
3.3.3 HF Crystal Oscillator (HFXO)
The BRD4185A Radio Board has a 38.4 MHz crystal mounted. For details regarding the crystal configuration, refer to application note
AN0016.2: Oscillator Design Considerations.
3.3.4 Matching Network for 2.4 GHz
The BRD4185A Radio Board incorporates a 2.4 GHz matching network which connects the 2.4 GHz RF input/output of the
EFR32BG22 to the one on-board printed Inverted-F antenna. The component values were optimized for the 2.4 GHz band RF performance and current consumption with 6 dBm output power.
For detailed description of the matching network, see section 4.2.1 Description of the 2.4 GHz RF Matching.
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