RF-Star RF-BM-BG22C3 User manual

RF-BM-BG22C3 EFR32BG22C224
Bluetooth 5.2 Low Energy Module
Version 1.1
Shenzhen RF-star Technology Co., Ltd.
May 26th, 2023
All rights reserved. Those responsible for unauthorized reproduction will be prosecuted.

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1 Device Overview
1.1 Description
RF-BM-BG22C3 is an RF module based on EFR32BG22C224F512GM32-C, one of the Gecko family of SoCs from
Silicon Labs, with a 32-bit ARM® Cortex®-M33 core with 76.8 MHz maximum operating frequency. It integrates a 38.4
MHz crystal, a matching, an antenna matching, a low-pass filter, and the antenna option (the one is chip antenna and a
half-hole ANT pin, and the other is the IPEX connector and a half-hole ANT pin). As for the hardware, it supports
Bluetooth 5.2 Low Energy, Low Power Node of Bluetooth Mesh, Direction Finding AoA/AoD and proprietary and also
has a range of analog and digital interfaces such as PRS, ADC, UART, SPI, I2C, PWM, ISO 7816, IrDA, I2S, EUART and
PDM. It features low power consumption, compact size, robust connection distance, and rigid reliability. An integrated
PA in the chip enables the module to reach up to 6 dBm TX power. 1.27-mm pitch stamp stick package for easy
assembling and cost-effective PCB design. As for the firmware, it can be preprogrammed with an RF-star BLE5.0 serial
communication protocol for simple programming.
1.2 Key Features
•RF Features
- Bluetooth 5.2 Low Energy
- Bluetooth Mesh Low Power Node
- Direction finding using Angle-of-Arrival (AoA) and
Angle-of-Departure (AoD)
- Proprietary
•Modulation
- 2 (G)FSK with fully configurable shaping
- OQPSK DSSS
- (G)MSK
•TX power: -28 dBm ~ 6 dBm
•Sensitivity
- -98.9 dBm @ 1 Mbit/s GFSK
- -96.2 dBm @ 2 Mbit/s GFSK
- -106.7 dBm @ 125 kbit/s GFSK
•32-bit 76.8 MHz ARM® Cortex®-M33 with DSP
instruction and floating-point unit for efficient signal
processing
•Memory
- Flash: 512 KB
- RAM: 32 KB
•Wide Operation Range
- Single power supply
⬧DC-DC mode: 2.2 V to 3.8 V
⬧Bypass mode: 1.8 V to 3.8 V
- Operating temperature: -40 °C to +85 °C
- Storage temperature: -40 °C to +125 °C
•Wide Peripherals
- 12-bit 1 Msps SAR ADC
- Up to 12 GPIOs with output state retention and
asynchronous interrupts
- 8 Channel DMA Controller
- 12 Channel Peripheral Reflex System (PRS)
- 4×16-bit Timer/Counter with 3
Compare/Capture/PWM channels
- 1×32-bit Timer/Counter with 3
Compare/Capture/PWM channels
- 32-bit RTC
- 24-bit Low Energy Timer for waveform generation
- 1×Watchdog Timer
- 2×Universal Synchronous/Asynchronous
Receiver/Transmitter
⬧UART
⬧SPI
⬧SmartCard (ISO 7816)
⬧IrDA
⬧I2S
- 1×Enhanced Universal Asynchronous Receiver /

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Transmitter (EUART)
- 2×I2C interface with SMBus support
- Digital microphone interface (PDM)
- Precision Low-Frequency RC Oscillator enabling
single-crystal operation
- RFSENSE with selective OOK mode
- Die temperature sensor with +/-2 degree C
accuracy across temperature range
•Security Features
- Secure Boot with Root of Trust and Secure Loader
(RTSL)
- Hardware Cryptographic Acceleration for
AES128/256, SHA-1, SHA-2 (up to 256-bit), ECC
(up to 256-bit), ECDSA, and ECDH
- True Random Number Generator (TRNG) compliant
with NIST SP800-90 and AIS-31
- ARM® TrustZone®
- Secure Debug with lock / unlock
•Transmission range:
- RF-BM-BG22C3: 110 m (@ PCB antenna, 1
Mbps/s); 135 m (@ PCB antenna, 125 kbps/s)
•Dimension: 8 mm x 8 mm x 1.82 mm
1.3 Applications
•Asset tags and beacons
•Consumer electronics remote controls
•Portable medical
•Sports, fitness and wellness devices
•Connected home
•Building automation and security
1.4 Functional Block Diagram
Figure 1. Functional Block Diagram of RF-BM-BG22C3
EFR32BG22
GPIOs
Debug
Reset
Low-Pass Filter
Power Supply
DC-DC mode: 2.2 V to 3.8 V
Bypass mode: 1.8 V to 3.8 V
38.4 MHz
Matching
Half-Hole Interface
Chip Antenna

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1.5 Part Number Conventions
The part numbers are of the form of RF-BM-BG22C3 where the fields are defined as follows:
Figure 2. Part Number Conventions of RF-BM-BG22C3
RF
BM
BG22
Company Name
RF-STAR
Wireless Type
Bluetooth Module
Chipset
EFR32BG22 Series
-
-
C
Module Version
The C HW Version
3
IC Code
EFR32BG22C224

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Table of Contents
1 Device Overview............................................................................................................................................................. 1
1.1 Description............................................................................................................................................................ 1
1.2 Key Features ....................................................................................................................................................... 1
1.3 Applications.......................................................................................................................................................... 2
1.4 Functional Block Diagram .............................................................................................................................. 2
1.5 Part Number Conventions.............................................................................................................................. 3
Table of Contents................................................................................................................................................................ 4
2 Module Configuration and Functions ...................................................................................................................... 6
2.1 Module Parameters........................................................................................................................................... 6
2.2 Module Pin Diagram ......................................................................................................................................... 7
2.3 Pin Functions....................................................................................................................................................... 7
3 Specifications ................................................................................................................................................................... 9
3.1 Recommended Operating Conditions ....................................................................................................... 9
3.2 Handling Ratings................................................................................................................................................ 9
3.3 Current Consumption ....................................................................................................................................... 9
4 Setting of Frequency Offset Register....................................................................................................................10
5 Application, Implementation, and Layout.............................................................................................................12
5.1 Module Photos..................................................................................................................................................12
5.2 Recommended PCB Footprint....................................................................................................................12
5.3 Schematic Diagram.........................................................................................................................................13
5.4 Reference Design............................................................................................................................................13
5.5 Antenna................................................................................................................................................................14
5.5.1 Antenna Design Recommendation ..............................................................................................14
5.5.2 Antenna Output Mode Modification..............................................................................................14
5.5.3 External Antenna Design Recommendation of the Half-Hole ANT Pin..........................15
5.6 Basic Operation of Hardware Design ......................................................................................................16
5.7 Trouble Shooting..............................................................................................................................................17
5.7.1 Unsatisfactory Transmission Distance........................................................................................17
5.7.2 Vulnerable Module..............................................................................................................................17
5.7.3 High Bit Error Rate .............................................................................................................................17
5.8 Electrostatics Discharge Warnings ...........................................................................................................18
5.9 Soldering and Reflow Condition.................................................................................................................18

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6 Optional Package Specification ..............................................................................................................................20
7 Revision History ............................................................................................................................................................22
8 Contact Us.......................................................................................................................................................................23

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2 Module Configuration and Functions
2.1 Module Parameters
Table 1. Parameters of RF-BM-BG22C3
Chipset
EFR32BG22C224F512GM32-C
Supply Power Voltage
DC-DC mode: 2.2 V ~ 3.8 V, recommended to 3.3 V
Bypass mode: 1.8 V ~ 3.8 V, recommended to 3.3 V
Frequency
2402 MHz ~ 2480 MHz
Transmit Power
-28.0 dBm ~ 6 dBm (typical: 0 dBm)
Receiving Sensitivity
-98.9 dBm sensitivity @ 1 Mbit/s GFSK
-96.2 dBm sensitivity @ 2 Mbit/s GFSK
-106.7 dBm sensitivity @ 125 kbps GFSK
GPIO
12
Crystal
38.4 MHz
RAM
32 KB
Flash
512 KB
Package
SMT Packaging (1.27-mm half-hole pitch stamp stick)
Frequency Error
±24 kHz
Dimension
8 mm x 8 mm x 1.82 mm
Type of Antenna
Chip antenna, half-hole ANT pin
Operating Temperature
-40 ℃ ～ +85 ℃
Storage Temperature
-40 ℃ ～ +125 ℃

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2.2 Module Pin Diagram
Figure 3. Pin Diagram of RF-BM-BG22C3
2.3 Pin Functions
Table 2. Pin Functions of RF-BM-BG22C3
Pin
Name
Chip Pin
Pin Type
Description
1
PA06
PA06
GPIO
2
PA05
PA05
GPIO
3
PA04
PA04
GPIO
4
PA03
PA03
GPIO
5
SWDIO
PA02
GPIO
6
SWCLK
PA01
GPIO
7
PD01
PD01
GPIO
8
RESET
RESET
-
Reset, active low, internal pull-up. The max. power
supply of this pin is 1.8 V under DC-DC mode.
9
PC01
PC01
GPIO
10
PB00
PB00
GPIO
11
PC03
PC03
GPIO

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12
PB01
PB01
GPIO
13
PC05
PC05
GPIO
14
VCC
VCC
VCC
2.2 V ~ 3.8 V, recommended to 3.3 V
15
GND
GND
-
Ground
16
EXT_ANT
EXT_ANT
-
External antenna pin.

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3 Specifications
3.1 Recommended Operating Conditions
The functional operation does not guarantee performance beyond the limits of the conditional parameter values in the
table below. Long-term work beyond this limit will affect the reliability of the module more or less.
Table 3. Recommended Operating Conditions of RF-BM-BG22C3
Items
Condition
Min.
Typ.
Max.
Unit
Operating Supply Voltage
DC-DC mode
2.2
3.3
3.8
V
Bypass mode
1.8
3.3
3.8
V
Frequency Range
2402
2480
MHz
Operating Temperature
/
-40
+25
+85
℃
Environmental Hot Pendulum
/
-20
+20
℃/min
3.2 Handling Ratings
Table 4. Handling Ratings of RF-BM-BG22C3
Items
Condition
Min.
Typ.
Max.
Unit
Storage Temperature
Tstg
-40
+25
+125
℃
Human Body Model
HBM
±2000
V
Moisture Sensitivity Level
3
Charged Device Model
±500
V
3.3 Current Consumption
Table 5. Current Consumption of RF-BM-BG22C3
Hardware Version: 1.0a
Test Condition
FLUKE15B+ multimeter, load connects to DSA1030 spectrum analyzer, offset: 0.2,
RBW = 100 KHz
Stand-by
1 A
Transmitting Current
Set Tx Power
Actual Tx Power
Actual Current
0 dBm
-0.5 dBm
4.0 mA
Receiving Current
2.5 mA
Note: The test method is closely related to the current. For example, the output load antenna is different from the
standard 50 Ω test data.

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4 Setting of Frequency Offset Register
The setting of the frequency offset register can be regarded as the auxiliary setting of modifying the frequency offset for
the hardware RF part.
If the frequency offset is needed to be modified, you can find the sl_device_init_hfxo_config.h file in the corresponding
project and modify the CTUNE value.
Take the empty_RGB project as an example:
Oen the project, find the Project Explorer window, and open the project folder, as shown in the following figure.
Then choose the config folder, find the sl_device_init_hfxo_config.h file, and double-click to open it, as shown in the
figure below.

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Find SL_DEVICE_INIT_HFXO_CTUNE, the official default value of SiliconLabs is 140, RF-star changes it to 72
according to the requirements of the development board hardware RF part.
Remark: This is the value for RF-star’s standard EFR32BG22 series modules, the value of the other customized products
needs to be confirmed.
If the user needs to change to other values, you can directly modify it (Value range: 0 ~ 255). As shown below.

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5 Application, Implementation, and Layout
5.1 Module Photos
Figure 4. Photos of RF-BM-BG22C3
5.2 Recommended PCB Footprint
Figure 5. Recommended PCB Footprint of RF-BM-BG22C3 (mm)

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5.3 Schematic Diagram
Figure 6. Schematic Diagram of RF-BM-BG22C3
5.4 Reference Design
Figure 7. Reference Design of RF-BM-BG22Cx

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5.5 Antenna
5.5.1 Antenna Design Recommendation
1. The antenna installation structure has a great influence on the module performance. It is necessary to ensure the
antenna is exposed and preferably vertically upward. When the module is installed inside of the case, a high-quality
antenna extension wire can be used to extend the antenna to the outside of the case.
2. The antenna must not be installed inside the metal case, which will cause the transmission distance to be greatly
weakened.
3. The recommendation of antenna layout.
The inverted-F antenna position on PCB is free-space electromagnetic radiation. The location and layout of the
antenna are key factors to increase the data rate and transmission range.
Therefore, the layout of the module antenna location and routing is recommended as follows:
（1）Place the antenna on the edge (corner) of the PCB.
（2）Make sure that there is no signal line or copper foil in each layer below the antenna.
（3）It is best to hollow out the antenna position in the following figure to ensure that the S11 of the module is
minimally affected.
Figure 8. Recommendation of Antenna Layout
Note: The hollow-out position is based on the antenna used.
5.5.2 Antenna Output Mode Modification
1. RF-BM-BG22C3 has two antenna output modes. The one is an onboard chip antenna and the other is a stamp half-
hole output (ANT pin, see pin function table for details).

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The default delivery is the chip antenna. If you want to use the external antenna by the ANT pin, pls disassembly the
chip antenna. The location of the chip antenna is shown in the figure below.
Figure 9. Antenna Output Mode Change of RF-BM-BG22C3
5.5.3 External Antenna Design Recommendation of the Half-Hole ANT Pin
1. A Π-type matching circuit is reserved for the antenna, and 50 Ω impedance control is performed on the RF traces.
The traces are as short as possible, and 135° or arc traces are used as much as possible. No vias are used to
change layers. More GND vias are placed around the RF traces.
Figure 10. Reference Design of the External Antenna
Figure 11. Reference Design of the External Antenna Traces
2. The RF trace width and copper-clad spacing can be calculated by SI9000 software, and the impedance is controlled
to 50 Ω according to the actual board thickness, number of layers, plate, dielectric thickness, dielectric constant,
copper thickness, line width, line spacing, and solder mask thickness.

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Example: FR4 is a double-layer board with a thickness of 1.0 mm. Through calculation, the width of the trace is
0.8254 mm, and the spacing between traces and copper is 0.22 mm.
Figure 12. SI9000 Impedance Calculation Diagram
5.6 Basic Operation of Hardware Design
1. It is recommended to offer the module a DC stabilized power supply, a tiny power supply ripple coefficient, and
reliable ground. Please pay attention to the correct connection between the positive and negative poles of the power
supply. Otherwise, the reverse connection may cause permanent damage to the module;
2. Please ensure the supply voltage is between the recommended values. The module will be permanently damaged
if the voltage exceeds the maximum value. Please ensure a stable power supply and no frequently fluctuating
voltage.
3. When designing the power supply circuit for the module, it is recommended to reserve more than 30% of the margin,
which is beneficial to the long-term stable operation of the whole machine. The module should be far away from the
power electromagnetic, transformer, high-frequency wiring, and other parts with large electromagnetic interference.
4. The bottom of the module should avoid high-frequency digital routing, high-frequency analog routing, and power
routing. If it has to route the wire on the bottom of the module, for example, it is assumed that the module is soldered
to the Top Layer, the copper must be spread on the connection part of the top layer and the module, and be close
to the digital part of the module and routed in the Bottom Layer (all copper is well-grounded).
5. Assuming that the module is soldered or placed in the Top Layer, it is also wrong to randomly route the Bottom Layer
or other layers, which will affect the spurs and receiving sensitivity of the module to some degree;
6. Assuming that there are devices with large electromagnetic interference around the module, which will greatly affect
the module performance. It is recommended to stay away from the module according to the strength of the

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interference. If circumstances permit, appropriate isolation and shielding can be done.
7. Assuming that there are routings of large electromagnetic interference around the module (high-frequency digital,
high-frequency analog, power routings), which will also greatly affect the module performance. It is recommended
to stay away from the module according to the strength of the interference. If circumstances permit, appropriate
isolation and shielding can be done.
8. It is recommended to stay away from the devices whose TTL protocol is the same 2.4 GHz physical layer, for
example, USB 3.0.
5.7 Trouble Shooting
5.7.1 Unsatisfactory Transmission Distance
1. When there is a linear communication obstacle, the communication distance will be correspondingly weakened.
Temperature, humidity, and co-channel interference will lead to an increase in the communication packet loss rate.
The performances of ground absorption and reflection of radio waves will be poor when the module is tested close
to the ground.
2. Seawater has a strong ability to absorb radio waves, so the test results by the seaside are poor.
3. The signal attenuation will be very obvious if there is metal near the antenna or if the module is placed inside the
metal shell.
4. The incorrect power register set or the high data rate in the open air may shorten the communication distance. The
higher the data rate, the closer the distance.
5. The low voltage of the power supply is lower than the recommended value at ambient temperature, and the lower
the voltage, the smaller the power is.
6. The unmatchable antennas and modules or the poor quality of antenna will affect the communication distance.
5.7.2 Vulnerable Module
1. Please ensure the supply voltage is between the recommended values. The module will be permanently damaged
if the voltage exceeds the maximum value. Please ensure a stable power supply and no frequently fluctuating
voltage.
2. Please ensure the anti-static installation and the electrostatic sensitivity of high-frequency devices.
3. Due to some humidity-sensitive components, please ensure the suitable humidity during installation and application.
If there is no special demand, it is not recommended to use at too high or too low temperature.
5.7.3 High Bit Error Rate
1. There are co-channel signal interferences nearby. It is recommended to be away from the interference sources or
modify the frequency and channel to avoid interferences.

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2. The unsatisfactory power supply may also cause garbled. It is necessary to ensure the power supply's reliability.
3. If the extension wire or feeder wire is of poor quality or too long, the bit error rate will be high.
5.8 Electrostatics Discharge Warnings
The module will be damaged by the discharge of static. RF-star suggests that all modules should follow the 3 precautions
below:
1. According to the anti-static measures, bare hands are not allowed to touch modules.
2. Modules must be placed in anti-static areas.
3. Take the anti-static circuitry (when inputting HV or VHF) into consideration in product design.
Static may result in the degradation in performance of the module, even causing failure.
5.9 Soldering and Reflow Condition
1. Heating method: Conventional Convection or IR/convection.
2. Solder paste composition: Sn96.5/Ag3.0/Cu0.5
3. Allowable reflow soldering times: 2 times based on the following reflow soldering profile.
4. Temperature profile: Reflow soldering shall be done according to the following temperature profile.
5. Peak temperature: 245 ℃.
Table 6. Temperature Table of Soldering and Reflow
Profile Feature
Sn-Pb Assembly
Pb-Free Assembly
Solder Paste
Sn63 / Pb37
Sn96.5 / Ag3.0 / Cu0.5
Min. Preheating Temperature (Tmin)
100 ℃
150 ℃
Max. Preheating Temperature (Tmax)
150 ℃
200 ℃
Preheating Time (Tmin to Tmax) (t1)
60 s ~ 120 s
60 s ~ 120 s
Average Ascend Rate (Tmax to Tp)
Max. 3 ℃/s
Max. 3 ℃/s
Liquid Temperature (TL)
183 ℃
217 ℃
Time above Liquidus (tL)
60 s ~ 90 s
30 s ~ 90 s
Peak Temperature (Tp)
220 ℃ ~ 235 ℃
230 ℃ ~ 250 ℃
Average Descend Rate (Tpto Tmax)
Max. 6 ℃/s
Max. 6 ℃/s
Time from 25 ℃ to Peak Temperature (t2)
Max. 6 minutes
Max. 8 minutes
Time of Soldering Zone (tP)
20±10 s
20±10 s

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Figure 13. Recommended Reflow for Lead-Free Solder