RF-Star CC254 Series User manual

RF-BM-S02, RF-BM-S02A and RF-BM-S02I
CC254X Series
Bluetooth Low Energy Module
Version 1.0
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 Module Series
There is a series of RF-BM-S02x Bluetooth Low Energy modules. All of them are based on TI CC254X (CC2540 and
CC2541) SoC series. Because the CC254X series ICs are compatible in package, pins, and peripherals, those modules
are pin-to-pin compatible with each other as well.
Table 1. Module Series of RF-BM-S02x
Model
Antenna Output
Mode
Chip Model
TX Power
FLASH
RAM
Peripherals
S02
PCB onboard
CC2540
+4 dBm
256 KB
8 KB
USB, PWM, ADC, IR,
WATCHDOG
S02I
IPEX connector
S02A
PCB onboard
CC2541
0 dBm
256 KB
8 KB
I2C, PWM, ADC, IR,
WATCHDOG
1.2 Description
RF-BM-S02, RF-BM-S02A, and RF-BM-S02I are Bluetooth Low Energy (BLE) module based on TI CC254X (CC2540
and CC2541), an 8051 core BLE System-on-Chip (SoC). This PCB module integrates a 32 MHz crystal, a 32.768 kHz
crystal, an LC balun, an RF matching filter, and a meander line PCB antenna (S02 and S02A) or an IPEX connector
(S02I). It is pre-programmed with the BLE 4.0 stack and an application communication protocol Very low-power sleep
modes are available. Short transition times between operating modes further enable low power consumption. RF-BM-
S02 is pin-compatible with the RF-BM-S02A and RF-BM-S02I in SMT package, if the USB is not used on the RF-BM-
S02 & RF-BM-S02I and the I2C/extra I/O is not used on the RF-BM-S02A. Compared to the RF-BM-S02 and RF-BM-
S02I, the RF-BM-S02A provides lower RF current consumption. The RF-BM-S02A does not have the USB interface of
the RF-BM-S02 and RF-BM-S02I, and provides lower maximum output power in TX mode. The RF-BM-S02A also adds
a HW I2C interface.
1.3 Key Features
•RF
- Bluetooth low energy compatible protocol
stack for single-mode
- Excellent link budget (up to 97 dBm),
Enabling long-range applications without
external front end
- Accurate Digital Received Signal-Strength
Indicator (RSSI)
•Microcontroller
- High-performance and low-power 8051
microcontroller core
- In-system-programmable flash of 256 KB
- 8-KB SRAM
•Peripherals

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- 12 Bit ADC with eight channels and
configurable resolution
- Integrated high-power op-amp and ultra-low
power comparator
- General-purpose timers (one 16-bits, two 8-
bits)
- 13 General-purpose I/O pins
- 32 kHz sleep timer with capture
- Two powerful USARTs with support for
several serial protocols
- IR generation Circuity
- AES security coprocessor
- Battery monitor and temperature sensor
- RF-BM-S02/S02I:
➢Full speed USB interface
➢Each CC2540 contains a unique 48-bit
IEEE address
- RF-BM-S02A:
➢I2C interface
➢2 I/O pins have LED driving capabilities
•Low Power
- Active mode RX down to 19.6 mA
- Active mode TX (–6 dBm): 24 mA
- Power mode 1 (3-μs wake-up): 235 μA
- Power mode 2 (sleep timer on): 0.9 μA
- Power mode 3 (external interrupts): 0.4 μA
- Wide supply voltage range (2 V ~ 3.6 V)
- Full RAM and register retention in all power
modes
•Dimension: 15.2 mm x 11.2 mm SMT Package
1.4 Applications
•2.4-GHz Bluetooth low energy system
•Mobile phone accessories
•Sports and leisure equipment
•Consumer electronics
•Human interface devices
•Keyboard, mouse
•Remote control
•USB dongles
•Health care and medical
•Smart lighting
1.5 Functional Block Diagram
Figure 1. Functional Block Diagram of RF-BM-S02x
CC254X
GPIO
UART
USB(S02/S02
I)
I2C(S02A)
LC Balun
S02/S02A: PCB
Antenna
S02I: IPEX Connector
RF-N
RF-P
Filter &
Matching
Reset
Power Supply
2.0 V ~ 3.6 V
32.0 MHz
32.768 kHz

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1.6 Part Number Conventions
The part numbers are of the form of RF-BM-S02x where the fields are defined as follows:
Figure 2. Part Number Conventions of RF-BM-S02x
RF
BM
S
Company Name
RF-STAR
Wireless Type
Bluetooth Module
Module Size
Small Type
-
-
02(A)
Chipset
S02: CC2540; S02A: CC2541
I
Antenna Type
I: IPEX Connector

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Table of Contents
1 Device Overview............................................................................................................................................................. 1
1.1 Module Series ..................................................................................................................................................... 1
1.2 Description............................................................................................................................................................ 1
1.3 Key Features ....................................................................................................................................................... 1
1.4 Applications.......................................................................................................................................................... 2
1.5 Functional Block Diagram .............................................................................................................................. 2
1.6 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....................................................................................................................................................... 8
3 Specifications ................................................................................................................................................................... 9
3.1 Recommended Operating Conditions ....................................................................................................... 9
3.2 Handling Ratings................................................................................................................................................ 9
4 Application, Implementation, and Layout.............................................................................................................10
4.1 Module Photos..................................................................................................................................................10
4.2 Recommended PCB Footprint....................................................................................................................11
4.3 Schematic Diagram.........................................................................................................................................12
4.4 Reference Design............................................................................................................................................12
4.5 Antenna................................................................................................................................................................13
4.5.1 Antenna Design Recommendation ..............................................................................................13
5.4.2 IPEX Connector Specification........................................................................................................14
4.6 Basic Operation of Hardware Design ......................................................................................................14
4.7 Trouble Shooting..............................................................................................................................................15
4.7.1 Unsatisfactory Transmission Distance........................................................................................15
4.7.2 Vulnerable Module..............................................................................................................................16
4.7.3 High Bit Error Rate .............................................................................................................................16
4.8 Electrostatics Discharge Warnings ...........................................................................................................16
4.9 Soldering and Reflow Condition.................................................................................................................16
5 Optional Package Specification ..............................................................................................................................18

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6 Certification .....................................................................................................................................................................20
6.1 FCC.......................................................................................................................................................................20
6.2 CE..........................................................................................................................................................................20
6.3 RoHS ....................................................................................................................................................................21
6.4 Reach ...................................................................................................................................................................21
7 Revision History ............................................................................................................................................................22
8 Contact Us.......................................................................................................................................................................23

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2 Module Configuration and Functions
2.1 Module Parameters
Table 2. Parameters of RF-BM-S02x
Chipset
RF-BM-S02/S02I: CC2540
RF-BM-S02A: CC2541
Supply Power Voltage
2.0 V ~ 3.6 V, recommended to 3.3 V
Frequency
2402 MHz ~ 2480 MHz
Transmit Power
RF-BM-S02/S02I: -23.0 dBm ~ +4.0 dBm
RF-BM-S02A: -23.0 dBm ~ 0 dBm
Receiving Sensitivity (low-gain mode)
-87 dBm
Receiving Sensitivity (high-gain mode)
-93 dBm
GPIO
13
Crystal
32 MHz
RAM
8 KB
Flash
256 KB
Package
SMT Packaging (1.27-mm half-hole pitch stamp stick)
Frequency Error
±20 kHz
Dimension
15.2 mm x 11.2 mm x 1.7 mm
Type of Antenna
PCB Antenna
Operating Temperature
-40 ℃～+85 ℃
Storage Temperature
-40 ℃～+125 ℃
RX Current
19.6 mA
TX Current (-6 dBm)
24.0 mA
Power mode 1 (3-μs wake-up)
235 μA
Power mode 2 (sleep timer on)
0.9 μA
Power mode 3 (external interrupts)
0.4 μA

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2.2 Module Pin Diagram
RF-BM-S02 RF-BM-S02I
RF-BM-S02A
Figure 3. Pin Diagram of RF-BM-S02x

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2.3 Pin Functions
Table 3. Pin Functions of RF-BM-S02x
Pin
Name
Chip Pin
Pin Type
Description
1
GND
-
GND
Ground
2
VCC
-
Power
Power supply 2.0 V ~ 3.6 V
3
P22
P2_2
I/O
4
P21
P2_1
I/O
5
RESET
RST
RESET
Reset, active low.
6
P20
P2_0
I/O
7
P17
P1_7
I/O
8
USB_P
USB+
USB+
USB+ (For RF-BM-S02 and RF-BM-S02I)
I2C_SCL
I2C_SCL
I/O
I2C_SCL (For RF-BM-S02A)
9
USB_N
USB-
USB-
USB- (For RF-BM-S02 and RF-BM-S02I)
I2C_SDA
I2C_SDA
I/O
I2C_SDA (For RF-BM-S02A)
10
P12
P1_2
I/O
11
P11
P1_1
I/O
12
P07
P0_7
I/O
13
P06
P0_6
I/O
14
P05
P0_5
I/O
15
P04
P0_4
I/O
16
P03
P0_3
I/O
17
P02
P0_2
I/O
18
P01
P0_1
I/O

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3 Specifications
3.1 Recommended Operating Conditions
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 4. Recommended Operating Conditions of RF-BM-S02x
Items
Condition
Min.
Typ.
Max.
Unit
Operating Supply Voltage
Battery Mode
2.0
3.3
3.6
V
Operating Temperature
/
-40
+25
+85
℃
Environmental Hot Pendulum
/
-20
+20
℃/min
3.2 Handling Ratings
Table 5. Handling Ratings of RF-BM-S02x
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
±750
V

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4 Application, Implementation, and Layout
4.1 Module Photos
RF-BM-S02 RF-BM-S02A
RF-BM-S02I
Figure 4. Photos of RF-BM-S02x

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4.2 Recommended PCB Footprint
RF-BM-S02(A)
RF-BM-S02I
Figure 5. Recommended PCB Footprint of RF-BM-S02 (mm)

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4.3 Schematic Diagram
Figure 6. Schematic Diagram of RF-BM-S02x
4.4 Reference Design
Figure 7. Reference Design of RF-BM-S02x

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4.5 Antenna
4.5.1 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.

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5.4.2 IPEX Connector Specification
RF-BM-S02I module is integrated the IPEX version 1 antenna seat, the specification of the antenna seat is as follows:
Figure 9. Specification of Antenna Seat
The specification of the IPEX wire end is as follows:
Figure 10. Specification of IPEX Wire
4.6 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

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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
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.
4.7 Trouble Shooting
4.7.1 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 performance 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.

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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 the antenna will affect the communication distance.
4.7.2 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 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.
4.7.3 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.
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.
4.8 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.
4.9 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 ℃.

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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
Figure 11. Recommended Reflow for Lead-Free Solder

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5 Optional Package Specification
The default package method is by tray. If you need the modules to be shipped by tape & reel, pls contact us in advance.
Figure 12. Default Package by Tray

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Figure 13. Package by Tape & Reel