Silicon Laboratories EFR32MG User manual

EFR32MG 2.4 GHz 19.5 dBm Radio Board
BRD4154A Reference Manual
The EFR32MG family of Wireless SoCs deliver a high perform-
ance, low energy wireless solution integrated into a small form
factor package.
By combining a high performance 2.4 GHz RF transceiver with an energy efficient 32-bit
MCU, the family provides designers the ultimate in flexibility with a family of pin-compati-
ble devices that scale from 128/256 kB of flash and 16/32 kB of RAM. The ultra-low
power operating modes and fast wake-up times of the Silicon Labs energy friendly 32-
bit MCUs, combined with the low transmit and receive power consumption of the 2.4
GHz radio, result in a solution optimized for battery powered applications.
RADIO BOARD FEATURES
• Wireless SoC:
EFR32MG1P732F256GM32
• CPU core: ARM Cortex-M4 with FPU
• Flash memory: 256 kB + 512 kB
• RAM: 32 kB
• Operation frequency: 2.4 GHz
• Transmit power: 19.5 dBm
• Integrated PCB antenna, UFL connector
(optional).
• Crystals for LFXO and HFXO: 32.768 kHz
and 38.4 MHz.
To develop and/or evaluate the EFR32 Mighty Gecko the BRD4154A Radio Board can
be connected to the Wireless Starter Kit Mainboard to get access to display, buttons and
additional features from Expansion Boards.
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1. Introduction
The EFR32 Mighty Gecko Radio Boards provide a development platform (together with the Wireless Starter Kit Mainboard) for the
Silicon Labs EFR32 Mighty Gecko Wireless System on Chips and serve as reference designs for the matching network of the RF inter-
face.
The BRD4154A Radio Board is designed to the operate in the 2400-2483.5 MHz band with the RF matching network optimized to oper-
ate with 19.5 dBm output power.
To develop and/or evaluate the EFR32 Mighty Gecko the BRD4154A Radio Board can be connected to the Wireless Starter Kit Main-
board to get access to display, buttons and additional features from Expansion Boards and also to evaluate the performance of the RF
interface.
BRD4154A Reference Manual
Introduction
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2. Radio Board Connector
2.1 Introduction
The board-to-board connector scheme allows access to all EFR32MG1 GPIO pins as well as the RESETn signal. For more information
on the functions of the available pin functions, we refer you to the EFR32MG1 Datasheet.
2.2 Radio Board Connector Pin Associations
The figure below shows the pin mapping on the connector to the radio pins, to the I/O Expander pins (shown in brackets) and their
function on the Wireless Starter Kit Mainboard.
GND
F9 / PD13 / VCOM.RTS_CS / DISP_SCS
3v3
IOEXP_DBG_C2D / P36
P200
Upper Row
NC / P38
NC / P40
NC / P42
NC / P44
DEBUG.TMS_SWDIO / PF1 / F0
DISP_ENABLE ** / (P1.2) / F14
UIF_BUTTON0 / (P0.0) / PD14 / F12
UIF_LED0 ** / (P1.5) / F10
VCOM.CTS_SCLK / DISP_SCLK / PB11 / F8
DEBUG.RESET / RADIO_#RESET / P4
DEBUG.TDO_SWO / PF2 / F2
VCOM.TX_MOSI / DISP_SI / PA0 / F16
VCOM.TX_MOSI / DISP_SI / PA0 / F6
PTI_DATA / PB12 / F20
DISP_EXTCOMIN ** / (P1.3) / F18
USB_VBUS
5V
Board ID SCL
GND
Board ID SDA
USB_VREG
F7 / PA1 / VCOM.RX_MISO
F5 / (P1.1) / VCOM_ENABLE **
F3 / NC
F1 / PF0 / DEBUG.TCK_SWCLK
P45 / NC
P43 / NC
P41 / NC
P39 / NC
P37 / (P1.0) / SENSOR_ENABLE **
F11 / (P1.6) / UIF_LED1 **
F13 / PD15 / (P0.1) / UIF_BUTTON1
F15 / PB11 / COM.CTS_SCLK / DISP_SCLK
F17 / PD13 / VCOM.RTS_CS / DISP_SCS
F19 / PB13 / PTI_FRAME
F21 / NC
GND VMCU_IN
(P0.6) / PF3 / P0
P201
Lower Row
NC / P2
UIF_BUTTON0 / PD14 / P4
UIF_BUTTON1 / PD15 / P6
GND VRF_IN
P35 / IOEXP_DBG_C2CK
P7 / PD13 / VCOM.RTS_CS / DISP_SCS
P5 / PB11 / VCOM.CTS_SCLK / DISP_SCLK
P3 / PA1 / VCOM.RX_MISO
P1 / PA0 / VCOM.TX_MOSI / DISP_SI
P33 /
P31 /
P29 / PF2 / DEBUG.TDO_SWO
P27 / PF1 / DEBUG.TMS_SWDIO
P25 / PF0 / DEBUG.TCK_SWCLK
P23 / NC
P21 / NC
P19 / NC
P17 / NC
P15 / NC
P13 / PC10 / (P0.4)
P11 / NC
P9 / NC
NC / P34
NC / P32
NC / P30
NC / P28
NC / P26
NC / P24
NC / P22
NC / P20
NC / P18
PTI_FRAME / PB13 / P16
PTI_DATA / PB12 / P14
(P0.5) / PC11 / P12
PB15 * / P10
PB14 * / P8
* Connection is not available by default.
Can be enabled through solderable jumpers. See the schematic of the Radio Board.
** Connection is only available through the on-board I/O expander. The associated I/O expander ports are shown in brackets.
Figure 2.1. BRD4154A Radio Board Connector Pin Mapping
BRD4154A Reference Manual
Radio Board Connector
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3. Radio Board Block Summary
3.1 Introduction
This section gives a short introduction to the blocks of the BRD4154A Radio Board.
3.2 Radio Board Block Diagram
The block diagram of the BRD4154A Radio Board is shown in the figure below.
Inverted-F
PCB
Antenna
2.4 GHz RF
UFL
Connector
LF
Crystal
32.768k
HF
Crystal
38.4M
Radio
Board
Connectors
8 Mbit
MX25R
Serial Flash
I2C
24AA0024
Serial EEPROM
Matching
Network &
Path
Selection
GPIO
UART
Debug
Packet Trace
AEM
I2C
SPI
SPI
2.4 GHz RF
2.4 GHz RF
EFM8
I/O Expander
I2C
Debug
GPIO
EFR32
EFR32
Wireless SoC
Figure 3.1. BRD4154A Block Diagram
3.3 Radio Board Block Description
3.3.1 Wireless MCU
The BRD4154A EFR32 Mighty Gecko Radio Board incorporates an EFR32MG1P732F256GM32 Wireless System on Chip featuring
32-bit Cortex-M4 with FPU core, 256 kB + 512 kB of flash memory and 32 kB of RAM and a 2.4 GHz band transceiver with output
power up to 19.5 dBm. For additional information on the EFR32MG1P732F256GM32, refer to the EFR32MG1 Data Sheet.
3.3.2 LF Crystal Oscillator (LFXO)
The BRD4154A Radio Board has a 32.768 kHz crystal mounted.
3.3.3 HF Crystal Oscillator (HFXO)
The BRD4154A Radio Board has a 38.4 MHz crystal mounted.
3.3.4 Matching Network for 2.4 GHz
The BRD4154A Radio Board incorporates a 2.4 GHz matching network which connects the 2.4 GHz TRX pin of the EFR32MG1 to the
one on-board printed Inverted-F antenna. The component values were optimized for the 2.4 GHz band RF performace and current con-
sumption with 19.5 dBm output power.
BRD4154A Reference Manual
Radio Board Block Summary
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For detailed description of the matching network see Chapter 4.2.1 Description of the 2.4 GHz RF Matching.
3.3.5 Inverted-F Antenna
The BRD4154A Radio Board includes a printed Inverted-F antenna (IFA) tuned to have close to 50 Ohm impedance at the 2.4 GHz
band.
For detailed description of the antenna see Chapter 4.5 Inverted-F Antenna.
3.3.6 UFL Connector
To be able to perform conducted measurements Silicon Labs added an UFL connector to the Radio Board. The connector allows an
external 50 Ohm cable or antenna to be connected during design verification or testing.
Note: By default the output of the matching network is connected to the printed Inverted-F antenna by a series component. It can be
connected to the UFL connector as well through a series 0 Ohm resistor which is not mounted by default. For conducted measurements
through the UFL connector the series component to the antenna should be removed and the 0 Ohm resistor should be mounted (see
Chapter 4.2 Schematic of the RF Matching Network for further details).
3.3.7 Radio Board Connectors
Two dual-row, 0.05” pitch polarized connectors make up the BRD4154A Radio Board interface to the Wireless Starter Kit Mainboard.
For more information on the pin mapping between the EFR32MG1P732F256GM32 and the Radio Board Connector refer to Chapter
2.2 Radio Board Connector Pin Associations.
3.3.8 I/O Expander
Due to the I/O port constraint of the EFR32MG1P732F256GM32 the BRD4154A Radio Board has an EFM8 family MCU mounted as an
I/O port expander to be able to utilize additional Wireless Starter Kit Mainboard features (LEDs, display etc.).
For more information on the pin mapping between the I/O Expander and the Radio Board Connector refer to Chapter 2.2 Radio Board
Connector Pin Associations.
BRD4154A Reference Manual
Radio Board Block Summary
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4. RF Section
4.1 Introduction
This section gives a short introduction to the RF section of the BRD4154A.
4.2 Schematic of the RF Matching Network
The schematic of the RF section of the BRD4154A Radio Board is shown in the following figure.
GND
GND
GND
L2
P1
U.FL
3
2
1
C2
Ground
RF I/ORF Crystal
RF Analog Power
PA Power
U1B
EFR32
2G4RF_IOP 17
2G4RF_ION 16
RFVDD
9
HFXI
10
HFXO
11
PAVDD
18
RFVSS 14
PAVSS 15
L1 AT1
INVERTED_F
R2
0R
NM
R1
0R
C1
Path
Selection
Inverted-F
Antenna
2.4 GHz
Matching
Network
Test
Connector
TRX Matching &
Filter
GND
PAVDD
VDCDC
GND
HFXTAL_P
HFXTAL_N
C107
10P
L102
BLM18AG601SN1
1 2
L103
BLM18AG601SN1
1 2
C102
100P
C103
10P
C106
220N
Supply Filtering
Figure 4.1. Schematic of the RF Section of the BRD4154A
4.2.1 Description of the 2.4 GHz RF Matching
The 2.4 GHz matching connects the 2G4RF_IOP pin to the on-board printed Inverted-F Antenna. The 2G4RF_ION pin is connected to
ground. For higher output powers (13 dBm and above) beside the impedance matching circuitry it is recommended to use additional
harmonic filtering as well at the RF output. The targeted output power of the BRD4154A board is 19.5 dBm thus the RF output of the IC
is connected to the antenna through a four-element impedance matching and harmonic filter circuitry.
For conducted measurements the output of the matching network can also be connected to the UFL connector by relocating the series
R1 resistor (0 Ohm) to the R2 resistor position between the output of the matching and the UFL connector.
4.3 RF Section Power Supply
On the BRD4154A Radio Board the supply pin of the RF Analog Power (RFVDD) is connected directly ot the output of the on-chip DC-
DC converter while the supply for the 2.4 GHz PA (PAVDD) is provided directly by the mainboard. This way, by default, the DC-DC
converter provides 1.8 V for the RF analog section, the mainboard provides 3.3 V for the PA (for details, see the schematic of the
BRD4154A).
4.4 Bill of Materials for the 2.4 GHz Matching
The Bill of Materials of the 2.4 GHz matching network of the BRD4154A Radio Board is shown in the following table.
Table 4.1. Bill of Materials for the BRD4154A 2.4 GHz 19.5 dBm RF Matching Network
Component name Value Manufacturer Part Number
L1 1.8 nH Murata LQP15MN1N8W02
L2 3.0 nH Murata LQP15MN3N0W00
C1 2.0 pF Murata GRM1555C1H2R0WA01
C2 1.0 pF Murata GRM1555C1H1R0WA01
BRD4154A Reference Manual
RF Section
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4.5 Inverted-F Antenna
The BRD4154A Radio Board includes an on-board printed Inverted-F Antenna tuned for the 2.4 GHz band. Due to the design restric-
tions of the Radio Board the input of the antenna and the output of the matching network can't be placed directly next to each other thus
a 50 Ohm transmission line was necessary to connect them. The resulting impedance and reflection measured at the output of the
matcing network are shown in the following figure. As it can be observed the impedance is close to 50 Ohm (the reflection is better than
-10 dB) for the entire 2.4 GHz band.
Figure 4.2. Impedance and Reflection of the Inverted-F Antenna of the BRD4154A
BRD4154A Reference Manual
RF Section
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5. Mechanical Details
The BRD4154A EFR32 Mighty Gecko Radio Board is illustrated in the figures below.
EFR32xx
Frame of
the
Optional
Shielding
Can
45 mm
30 mm
DC-DC
Inductor
DC-DC
&
Supply
Filter
Caps.
PAVDD Supply
Filtering
Figure 5.1. BRD4154A Top View
24 mm
27.3 mm
28.6 mm
5 mm
Interface
Connector
Interface
Connector
15 mm
Board
Identification
Display
Enable
Selection
Figure 5.2. BRD4154A Bottom View
BRD4154A Reference Manual
Mechanical Details
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6. EMC Compliance
6.1 Introduction
Compliance of the fundamental and harmonic levels is tested against the following standards:
• 2.4 GHz:
• ETSI EN 300-328
• FCC 15.247
6.2 EMC Regulations for 2.4 GHz
6.2.1 ETSI EN 300-328 Emission Limits for the 2400-2483.5 MHz Band
Based on ETSI EN 300-328 the allowed maximum fundamental power for the 2400-2483.5 MHz band is 20 dBm EIRP. For the unwan-
ted emissions in the 1 GHz to 12.75 GHz domain the specified limit is -30 dBm EIRP.
6.2.2 FCC15.247 Emission Limits for the 2400-2483.5 MHz Band
FCC 15.247 allows conducted output power up to 1 Watt (30 dBm) in the 2400-2483.5 MHz band. For spurious emmissions the limit is
-20 dBc based on either conducted or radiated measurement, if the emission is not in a restricted band. The restricted bands are speci-
fied in FCC 15.205. In these bands the spurious emission levels must meet the levels set out in FCC 15.209. In the range from
960 MHz to the frequency of the 5th harmonic it is defined as 0.5 mV/m at 3 m distance (equals to -41.2 dBm in EIRP).
Additionally, for spurious frequencies above 1 GHz FCC 15.35 allows duty-cycle relaxation to the regulatory limits. For the EmberZNet
PRO the relaxation is 3.6 dB. So practically the -41.2 dBm limit can be modified to -37.6 dBm.
In case of operating in the 2400-2483.5 MHz band the 2nd, 3rd and 5th harmonics can fall into restricted bands so for those the
-37.6 dBm limit should be applied. For the 4th harmonic the -20 dBc limit should be applied.
6.2.3 Applied Emission Limits for the 2.4 GHz Band
The above ETSI limits are applied both for conducted and radiated measurements.
The FCC restricted band limits are radiated limits only. Besides that, Silicon Labs applies those to the conducted spectrum i.e. it is as-
sumed that in case of a custom board an antenna is used which has 0 dB gain at the fundamental and the harmonic frequencies. In that
theoretical case, based on the conducted measurement, the compliance with the radiated limits can be estimated.
The overall applied limits are shown in the table below.
Table 6.1. Applied Limits for Spurious Emissions for the 2.4 GHz Band
Harmonic Frequency Limit
2nd 4800~4967 MHz -37.6 dBm
3rd 7200~7450.5 MHz -37.6 dBm
4th 9600~9934 MHz -30 dBm
5th 12000~12417.5 MHz -37.6 dBm
BRD4154A Reference Manual
EMC Compliance
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7. RF Performance
7.1 Conducted Power Measurements
During measurements the BRD4154A Radio Board was attached to a Wireless Starter Kit Mainboard which was supplied by USB. The
voltage supply for the Radio Board was 3.3 V.
7.1.1 Conducted Measurements in the 2.4 GHz band
The BRD4154A board was connected directly to a Spectrum Analyzer through its UFL connector (the R1 resistor (0 Ohm) was removed
and a 0 Ohm resistor was soldered to the R2 resistor position). The supply for the radio (RFVDD) was 1.8 V provided by the on-chip
DC-DC converter, the supply for the power amplifier (PAVDD) was 3.3 V provided by the Motherboard (for details, see the schematic of
the BRD4154A). The transceiver was operated in continuous carrier transmission mode. The output power of the radio was set to 19.5
dBm.
The typical output spectrum is shown in the following figure.
Figure 7.1. Typical Output Spectrum of the BRD4154A
As it can be observed the fundamental is slightly lower than 19.5 dBm and the strongest unwanted emission is the double-frequency
harmonic but with its -56.45 dBm level it is under the -37.6 dBm applied limit with large margin.
Note: The conducted measurement is performed by connecting the on-board UFL connector to a Spectrum Analyzer through an SMA
Conversion Adapter (P/N: HRMJ-U.FLP(40)). This connection itself introduces approx. 0.3 dB insertion loss.
BRD4154A Reference Manual
RF Performance
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