RF-Star nRF52832 User manual

nRF52832 Bluetooth Low Energy
Master-Slave Module and Protocol
Version: V1.3
Shenzhen RF-star Technology Co., Ltd.
Sep. 11th, 2020

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RF-BM-ND04
RF-BM-ND04I
RF-BM-ND08

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Table of Contents
Table of Contents................................................................................................................................................................ 2
Table of Tables..................................................................................................................................................................... 4
Table of Figures................................................................................................................................................................... 5
1 Summary............................................................................................................................................................................ 6
2 Overview ............................................................................................................................................................................ 7
2.1 Introduction........................................................................................................................................................... 7
2.2 Features ................................................................................................................................................................ 7
2.3 Supporting Working Mode.............................................................................................................................. 8
2.4 Default Configuration at Slave Mode ......................................................................................................... 8
2.5 Default Configuration at Beacon Mode ..................................................................................................... 9
2.6 Device Status ...................................................................................................................................................... 9
2.7 Multi-Connection ................................................................................................................................................ 9
3 Package and Pin Assignment..................................................................................................................................11
3.1 RF-BM-ND04(I) ................................................................................................................................................11
3.2 RF-BM-ND08(I) ................................................................................................................................................14
4 UART Transparent Transmission Protocol (Bridge Mode) ...........................................................................17
5 BLE Protocol Specification (APP Interface) .......................................................................................................18
Service UUID ............................................................................................................................................................18
BLE Data Receiving UUID...................................................................................................................................18
BLE Data Transmitting UUID..............................................................................................................................18
AT Command Operation UUID...........................................................................................................................18
6 AT Command..................................................................................................................................................................19
6.1 AT Command Format .....................................................................................................................................19
6.2 AT Command List.............................................................................................................................................19
6.3 Detailed AT Command...................................................................................................................................21
•Enter AT Command Mode ......................................................................................................................21
•Exit AT Command Mode .........................................................................................................................21
•Device Name...............................................................................................................................................21
•Firmware Version.......................................................................................................................................22
•MAC Address ..............................................................................................................................................22

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•Serial Port Echo .........................................................................................................................................22
•Device Status Display..............................................................................................................................23
•Broadcast......................................................................................................................................................24
•Connection Interval...................................................................................................................................25
•Device Role..................................................................................................................................................26
•Slave Service ..............................................................................................................................................26
•Master Scan.................................................................................................................................................27
•Master Connection ....................................................................................................................................29
•Disconnect....................................................................................................................................................29
•Automatically Reconnection ..................................................................................................................30
•Specify the Role of Sending Data .......................................................................................................31
•Query Current Connected Devices.....................................................................................................32
•Designate Transmission Device...........................................................................................................32
•Delete Device..............................................................................................................................................33
•Observer........................................................................................................................................................33
•Beacon...........................................................................................................................................................34
•Tx Power.......................................................................................................................................................34
•Sleep Status ................................................................................................................................................35
•Baud Rate.....................................................................................................................................................36
•User Authentication...................................................................................................................................37
•Restart Device ............................................................................................................................................38
•Reset Device ...............................................................................................................................................38
7 Transparent Transmission Test ...............................................................................................................................39
7.1 Test by APP (Android)....................................................................................................................................39
7.2 Test by PC End.................................................................................................................................................41
Preparation before Use................................................................................................................................41
Connection Steps...........................................................................................................................................42
8 iOS APP Programming Reference.........................................................................................................................47
9. Master Reference Code (Transparent Transmission)...................................................................................50
10 Application, Implementation, and Layout..........................................................................................................51
10.1Antenna ..............................................................................................................................................................51
10.2 Reference Design .........................................................................................................................................52
10.3 Basic Operation of Hardware Design....................................................................................................53

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10.4 Trouble Shooting ...........................................................................................................................................54
10.4.1 Unsatisfactory Transmission Distance .....................................................................................54
10.4.2 Vulnerable Module ...........................................................................................................................54
10.4.3 High Bit Error Rate...........................................................................................................................55
10.5 Electrostatics Discharge Warnings.........................................................................................................55
10.6 Soldering and Reflow Condition ..............................................................................................................55
10.7 Optional Packaging ......................................................................................................................................56
11 Revision History ..........................................................................................................................................................57
12 Contact Us ....................................................................................................................................................................58
Table of Tables
Table 1. Power Consumption of nRF52832 .................................................................................................... 8
Table 2. Pin Functions of RF-BM-ND04(I).....................................................................................................12
Table 3. Pin Functions of RF-BM-ND08(I).....................................................................................................15
Table 4. AT Command Format Table................................................................................................................19
Table 5. AT Command List...................................................................................................................................19
Table 6. Temperature Table of Soldering and Reflow................................................................................55

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Table of Figures
Figure 1. Multi-Connection Diagram ................................................................................................................10
Figure 2. PCB Footprint of RF-BM-ND04 ......................................................................................................11
Figure 3. PCB Footprint of RF-BM-ND04I .....................................................................................................11
Figure 4. Pin Assignment of RF-BM-ND04(I) ...............................................................................................12
Figure 5. PCB Footprint of RF-BM-ND08 ......................................................................................................14
Figure 6. PCB Footprint of RF-BM-ND08I .....................................................................................................14
Figure 7. Pin Assignment of RF-BM-ND08(I) ...............................................................................................15
Figure 8. Specification of Antenna Seat .........................................................................................................51
Figure 9. Specification of IPEX Wire................................................................................................................51
Figure 10. Antenna Output Mode Change.....................................................................................................52
Figure 11. Reference Design of RF-BM-ND04 ............................................................................................52
Figure 12. Recommendation of Antenna Layout.........................................................................................54
Figure 13. Recommended Reflow for Lead Free Solder .........................................................................56
Figure 14. Optional Packaging Mode ..............................................................................................................56

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1 Summary
RF-BM-ND04(I) and RF-BM-ND08 are RF modules based on Nordic BLE SoC nRF52832QFAA with ARM® Cortex®-M4
32-bit processor. It integrates a 32.768 kHz and a 32 MHz crystal, an LC filter, an antenna matching and a meander line
inverted-F PCB antenna / or an IPEX connector. The modules support BLE stack v5.0 including the high-speed 2 Mbps
feature and can be preprogrammed with a serial interface communication protocols, such as NFC, ANT and 2.4 GHz
proprietary for simple programming. The modules also support Bluetooth mesh which can be run concurrently with
Bluetooth LE, enabling smartphones to provision, commission, configure and control mesh nodes. The module has NFC-
A Tag for use in simplified pairing and payment solutions. It also has numerous digital peripherals and interfaces such
as ADC, PDM, PWM, I2C and I2S for many applications. It features low power consumption, small size, robust connection
distance, and rigid reliability. 1.27-mm pitch stamp stick package for easy assembling and cost-effective PCB design.
RF-star can provide customers with the integration of the entire profiles, applications, radio and BLE protocol stack. With
compliance to Bluetooth Low Energy standard, the RF-star’s modules enable the creation of a new market for tiny, cost-
effective and power-efficient wireless consumer products such as watches, medical sensors, mice, TV remote controls
and fitness trainers.

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2 Overview
2.1 Introduction
The Bluetooth LE modules which are mentioned in this document can work in bridge mode (transparent transmission
mode).
After the module starts to broadcast, smart phone with specific APP running will scan and pair with it. When connection
is successful, the smart phone can monitor and control the module through Bluetooth protocol.
In bridge mode, user CPU can communicate with the mobile device bi-directionally through the serial ports of modules.
Users can also manage and control certain communication parameters through specific AT commands of serial ports.
The detailed meaning of the user data is defined by the upper applications. Mobile devices can write the module through
the APP. And the data written will be sent to the user CPU through serial ports. Then the module will transmit the data
packet from user CPU to the mobile devices automatically. Under the development in this mode, the user needs to
undertake the code design for master CPU and the APP for mobile devices.
In order to ensure the stability of the firmware, the module will start to work normally after 500 ms of power on.
2.2 Features
1. Easy to use, no need of any application experience of Bluetooth protocol stack.
2. Support BLE master mode, slave mode, master-slave mode and Beacon mode.
3. Support concurrent slave mode and master, that is, the module can connect to other slave devices when it is
connected by one master device.
4. Support multi-connection during master mode and master-slave mode. A maximum of 22 slave devices can be
connected at the same time. It is recommended to connect 3 or less slave devices for more stability.
5. Default connection interval of 7.5 ms, which makes quick connection and enhance the compatible stability of
Android and iOS phones.
6. UART design for user interface, full-duplex bi-directional communication, and support the minimum baud rate of
4800 bps and the maximum baud rate of 460800 bps.
7. Support software reset module by AT command.
8. Support acquire and modify the MAC address (to take effect after resetting) by AT command.
9. Support adjust the Bluetooth connection interval and control different transmit rates (dynamic power consumption
adjustment) by AT command.
10. Support adjust the transmit power, modify the broadcast interval, modify the serial port baud rate, modify the module

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name, by AT commands, please check for details in AT Command.
11. Support modify Service UUID by AT command.
12. AT commands can be sent through APP.
13. High-speed transparent transmission rate, stable transmission at 30 KB/s (when there is no serial port transmission
interval, the data transmitted directly according to the flow control IO change can reach the limit of 50K).
14. Ultra-low working power consumption, the measured power consumption of the module is as follows:
Table 1. Power Consumption of nRF52832
Event
Average Current
Test Condition / Remark
Sleep
2.62 µA
Broadcast
77.70 µA
Broadcast interval: 200 ms
Broadcast
30.01 µA
Broadcast interval: 500 ms
Broadcast
15.64 µA
Broadcast interval: 1000 ms
Broadcast
8.90 µA
Broadcast interval: 2000 ms
Broadcast
4.27 µA
Broadcast interval: 5000 ms
Connection
72.80 µA
Connection interval: 7.5 ms
Connection
38.28 µA
Connection interval: 30 ms
Connection
2.62 µA
Connection interval: 100 ms
2.3 Supporting Working Mode
The device supports four working modes as below:
1. BLE slave mode
2. BLE master mode
3. BLE master-slave mode
4. Beacon mode
The default role after power-on is the slave mode. The role can be switched to adjust the working mode through the AT
command "AT+ROLE". Please check the AT Command in detail. In the Beacon mode, the serial port is closed, the
mode only can be switched through the mobile APP.
2.4 Default Configuration at Slave Mode
1. Device name: RF-STAR-SMMT.
2. Broadcast interval: 200 ms.
3. Connection interval: 7.5 ms.
4. 128-bit UUID
5. Broadcast mode: connectable

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6. Device status: transparent transmission
2.5 Default Configuration at Beacon Mode
1. Company ID: 0x0059 (Nordic).
2. Major UUID: 0x0102.
3. Minor UUID: 0x0304.
4. RSSI: -50 dBm.
5. UUID: 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0x10.
The serial port is closed and unavailable in this mode.
2.6 Device Status
1. DEVICE START: The device starts to work.
2. S:CONNECTED: BLE slave is successfully connected.
3. S:DISCONNECTED: BLE slave is disconnected.
4. B:CONNECTED: Beacon is successfully connected.
5. B:DISCONNECTED: Beacon is disconnected.
6. “XX:XX:XX:XX:XX:XX CONNEDTED”: BLE master is successfully connected (The string in red is the MAC address
of the connected slave).
7. “XX:XX:XX:XX:XX:XX DISCONNECTED”: BLE master is disconnected (The string in red is the MAC address of the
disconnected slave).
8. DEVICE ERROR!: An abnormal error occurred in the device.
The above states can be turned on or off by the AT command. For details, please refer to AT Command.
2.7 Multi-Connection
1. Support multi-connection during master mode and master-slave mode. A maximum of 22 slave devices can be
connected at the same time. It is recommended to connect 3 or less slave devices for more stability.
2. If AT+CONNECT command failed to connect to the device (prompt FAIL), please check whether the stored device
list has reached the maximum number of storage (AT+DEV_DEL=? command to check the device list).
3. Multi-connection means multiple devices automatically reconnect. When an opposite device disconnects
abnormally, the device will initiate reconnection. Scan the surrounding BLE devices for 3 times before the
reconnection (once every 20 s). If the device is not found after the timeout of 3 scans, the master device will enter
the slow scan state, that is, the device scans the surrounding devices once every 5 minutes. If the device to be
connected is found, reconnect will be conducted.

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4. During multi-connection, the designated data transmission handle function is not saved after power off, and the
data will be transmitted between the default device and the device with a handle value of 0. After the user changes
the handle, if the corresponding handle device is disconnected, the handle value is automatically switched to the
next effective handle. (please refer to the command AT+CNT_LIST).
5. The user disconnects the devices by AT commands, and the automatically reconnection of the device is failed for
this time.
Recommendation:
The source of multi-connection data transmission is more complicated, such as the master-slave: the data may come
from the following 4 devices, so the data source should be included in the data packet, otherwise it cannot be identified
which device the data came from.
Figure 1. Multi-Connection Diagram

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3 Package and Pin Assignment
3.1 RF-BM-ND04(I)
RF-BM-ND04 is pin to pin compatible with and RF-BM-ND04I. The difference is that the antenna of RF-BM-ND04 is
PCB type, while RF-BM-ND04I is IPEX type.
Figure 2. PCB Footprint of RF-BM-ND04
Figure 3. PCB Footprint of RF-BM-ND04I

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Figure 4. Pin Assignment of RF-BM-ND04(I)
Table 2. Pin Functions of RF-BM-ND04(I)
Pin
Name
Function
Description
1
GND
GND
Ground
2
VCC
VCC
Power supply: 1.7 V ~ 3.6 V. Recommended to 3.3 V.
3
P21 / RST
I/O
Reset, active low.
4
P22
I/O
5
P23
I/O
6
P24
I/O
7
P25
I/O
8
P28
I/O
9
P29
I/O
10
P30
I/O
11
P26
I/O
12
P27
I/O
13
P02
I/O
14
P03
I/O
15
P04
I/O

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16
P05
RTS
(Require ToSend, send request) output signal, used to indicate
that the device is ready to receive data, active low.
17
P06
TX
Serial port TX
18
P07
CTS
(Clear ToSend, send permission) input signal, used to judge
whether it can send data to the other party, active low.
19
P08
RX
Serial port RX
20
P09
I/O
21
P10
I/O
22
P11
I/O
23
P12
I/O
24
P13
Wakeup IO
When the module is in sleep state, the module can be
awakened through this IO.
Active on falling edge
25
P14
I/O
26
P15
I/O
27
P16
I/O
28
SWDIO
－
Serial Wire Debug I/O for debug and programming
29
SWCLK
－
Serial wire debug clock input for debug and programming
30
P17
State indicator
Broadcast state indicator: in high level during broadcast, in low
level during connection (always on)
31
P18
I/O
32
P19
RESTORE
All parameters will be reset to factory settings after this pin is
set low for 3 s.
33
P20
I/O

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3.2 RF-BM-ND08(I)
RF-BM-ND08 is pin to pin compatible with and RF-BM-ND08I. The difference is that the antenna of RF-BM-ND08 is
PCB type, while RF-BM-ND08I is IPEX type. SWD debugging ports are on the bottom side of the module, which is not
pull out in the stamp half hole way, please refer to the module pin diagram for details.
Figure 5. PCB Footprint of RF-BM-ND08
Figure 6. PCB Footprint of RF-BM-ND08I

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Figure 7. Pin Assignment of RF-BM-ND08(I)
Table 3. Pin Functions of RF-BM-ND08(I)
Pin
Name
Function
Description
1
ANT
—
Antenna pin
2
GND
GND
Ground
3
VCC
VCC
Power supply: 1.7 V ~ 3.6 V. Recommended to 3.3 V.
4
P25
I/O
5
P17
State indicator
Broadcast state indicator: in high level during broadcast, in low
level during connection (always on)
6
P21/RST
I/O
Reset, active low.
7
P13
Wakeup IO
When the module is in sleep state, the module can be awakened
through this IO.
Active on falling edge
8
P28
I/O
9
P27
I/O
10
P26
I/O
11
P09
I/O
12
P10
I/O
13
P19
RESTORE
All parameters will be reset to factory settings after this pin is
set low for 3 s.
14
P20
I/O
15
P05
RTS
(Require ToSend, send request) output signal, used to indicate

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that the device is ready to recei
16
P07
CTS
(Clear ToSend, send permission) input signal, used to judge
whether it can send data to the other party, active low.
17
P06
TX
Serial port TX
18
P08
RX
Serial port RX
19
P03
I/O

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4 UART Transparent Transmission Protocol (Bridge Mode)
The bridge mode means to set up a bi-directional communication way between user CPU and mobile devices by the
mutual connection between serial port and user CPU. Users can reset serial port baud rate and BLE connection interval
by the specified AT commands (see the section “AT Command”). The module will have different data handling capability,
as per different serial port baud rates and BLE connection intervals. The default baud rate is set at 115200 bps.
Except for Beacon mode, the serial port is open by default in any mode. If this function needs to be closed, please use
the "AT+SLEEP=1" command to close the serial port.
The module can customize the serial port package according to the acquired MTU of the connected device. According
to the packet size, the packet will be sub-packed automatically and sent, with a maximum load of 244 Bytes for each
wireless sub-packet. Data packets from mobile devices to the module must be sub-packed automatically (into 1 ~ 244
Bytes/packet) before sending. The module will transmit them to the master RXD in turn, when received the packets.
1. The hardware protocol of serial port: 115200 bps, 8, no parity, 1 stop bit.
2. For reliable transparent transmission, please use flow control. Most of the serial port tools of PC-side do not have
CTS detection. It is recommended to use the software SecureCRT.
3. After the module is connected, BRTS needs to be pulled low if the master (MCU) has data to send to the BLE
module, and the data transmission can be started around 50 ms afterwards. BRTS should be pulled high by the
master after transmission finished and make the module exit the serial RX mode. Pay attention to that there will be
a delay after the data is transmitted, and confirm that the data transmission has been completely finished before
BRTS is pulled-high. Otherwise there will be data truncation.
4. When there is data upload request, the module will set BCTS low and start to transmit as soon as 500 μs, until data
transmission finishes.
5. If the mater BRTS is being kept a low level, the Bluetooth module will always be in serial port receiving mode and
the power consumption will be high.

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5 BLE Protocol Specification (APP Interface)
Service UUID
6E400001B5A3F393E0A9E50E24DCCA9E
BLE Data Receiving UUID
Characteristics UUID
6E400002B5A3F393E0A9E50E24DCCA9E
Executable operations
Write
Remarks
The BLE input is transmitted to the serial port output: After APP writes to this channel
through the BLE API interface, the data will be output from the serial port TX.
BLE Data Transmitting UUID
Characteristics UUID
6E400003B5A3F393E0A9E50E24DCCA9E
Executable operations
Notify
Remarks
The serial port input is transmitted to the BLE output, and the data input from the serial
port RX will be notified in this channel and sent to the mobile device.
AT Command Operation UUID
Characteristics UUID
6E400004B5A3F393E0A9E50E24DCCA9E
Executable operations
Write / Notify
Remarks
Supports all commands in the command list, any data will be processed as commands
(do not use +++ to enter the command mode), and users can operate without sending
carriage returns and line feeds (CRLF). The serial port must end with a CRLF.
The master needs to open notify to receive the data sent by the module.

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6 AT Command
6.1 AT Command Format
Table 4. AT Command Format Table
Type
Command
Format
Description
Test Command
AT+[x]=?
This command is used to query the parameters and value range of the
setting commands.
Query Command
AT+[x]?
This command returns the current value of the parameter.
Configure Command
AT+[x]=<…>
This command is used to set user-defined parameter values.
Note:
1. This command can be sent through APP and serial port.
2. The default baud rate of the serial port is 115200, 8 bit data bit, 1 stop bit, no parity.
3. Not every command has the above four types of commands.
4. The AT command must be capitalized and ended with a carriage return and line feed (CRLF).
5. The <> returned in the query AT command indicates the optional parameters, and [] indicates the required
parameters. If all parameters of the command are optional parameters, at least one parameter is needed to be filled,
otherwise it is also regarded as a command error.
Example: AT+ADS=<0,1>,<0,1>,<10,10240>, you can fill in AT+ADS=,,500.
6. The parameter positions that are not filled in the optional parameter command must be reserved. Refer to the
previous example.
6.2 AT Command List
Table 5. AT Command List
AT Command
Function
Remark
+++
Enter AT command mode.
AT+EXIT
Exit AT command mode.
Take effect immediately.
AT+NAME
Query / set device name.
Take effect after restart, save after power off.
AT+VERSION
Query firmware version.
AT+MAC
Query / set MAC address.
Take effect after restart, save after power off.
AT+ECHO
Query / set whether the serial port is echoed.
Take effect immediately, do not save after
power off.