Getting started with the X-NUCLEO-S2868A1 Sub-1 GHz 868 MHz RF expansion
board based on S2-LP radio for STM32 Nucleo
Introduction
The X-NUCLEO-S2868A1 expansion board is based on the S2-LP radio and operates in the 868 MHz ISM frequency band.
The expansion board is compatible with ST morpho and Arduino UNO R3 connectors.
The X-NUCLEO-S2868A1 interfaces with the STM32 Nucleo microcontroller via SPI connections and GPIO pins. You can
change some of the GPIOs by mounting or removing the resistors.
Figure 1.
X-NUCLEO-S2868A1 expansion board
UM2405 - Rev 2 - October 2018
For further information contact your local STMicroelectronics sales office.
www
.st.com
1Acronyms and abbreviations
Table 1. List of acronyms
AcronymDescription
AMRAutomatic meter reading
EEPROMElectrically erasable programmable read only memory
GHzGiga Hertz
GUIGraphical user interface
LEDLight emitting diode
MCUMicrocontroller unit
P2PPoint-to-point communication
RFRadio frequency communication
SPISerial peripheral interface
USBUniversal serial bus
wM-BusWireless metering bus
WSNWireless sensors network
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Acronyms and abbreviations
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2Getting started
2.1Overview
The X-NUCLEO-S2868A1 main features are:
Based on S2-LP radio
•
•S2-LP narrow band ultra-low power sub-1 GHz transceiver tuned for 860 - 940 MHz frequency band
•Programmable RF output power up to +16 dBm
•Modulation schemes: 2-FSK, 2-GFSK, 4-FSK, 4-GFSK, OOK and ASK
•Air data rate from 0.1 to 500 kbps
•Ultra-low power consumption: 7 mA RX and 10 mA TX at +10 dBm
•IEEE 802.15.4g hardware packet support with whitening, FEC, CRC and dual SYNC word detection
•RX and TX 128 byte FIFO buffers
•Support to wireless M-Bus
•Excellent performance of receiver sensitivity (up to -130 dBm)
•Automatic acknowledgement, retransmission and timeout protocol engine
•Compatible with STM32 Nucleo boards
•Compatible with Arduino UNO R3 connectors
•Support to SMD and SMA antennas
•BALF-SPI2-01D3 IPD balun for matching network and harmonics filter
•Sigfox compatible
•Sample firmware for P2P communication
•6LoWPAN compatible thanks to STM32Cube
•RoHS compliant
The X-NUCLEO-S2868A1 expansion board can be used for the evaluation of the S2-LP device in multiple
applications.
The following demo samples are available for testing:
•wM-Bus demo
•Point-to-point communication protocol demo
•6LoWPAN applications
•SigFox communication
You can develop other applications for evaluating the devices, such as:
•SigFox communication
•Automatic meter reading
•Home and building automation
•WSN
•Industrial monitoring and control
•Wireless fire and security alarm systems
UM2405
Getting started
2.2Hardware and software requirements
To use STM32 Nucleo development boards with the X-NUCLEO-S2868A1
as shown below.
UM2405 - Rev 2
expansion board, connect the boards
page 3/19
UM2405
Board setup
Figure 2. X-NUCLEO-S2868A1 expansion board connected to an STM32 Nucleo development board
The interconnection between the STM32 Nucleo and the X-NUCLEO-S2868A1 has been designed to allow using
any STM32 Nucleo board, although complete testing has been performed using NUCLEO-L053R8, NUCLEO-
F401RE
The following software and hardware specifications are required:
•a PC/laptop with Microsoft Windows (7 and above) to install the software package (X-CUBE-SUBG1)
•a type A USB to mini-B USB cable to connect the STM32 Nucleo board to the PC/laptop
•128 MB of RAM
•Approximately 40 MB of hard disk space for the firmware
•Approximately 15 MB of hard disk space for the wM-Bus GUI
The use of the wM-Bus concentrator with the GUI requires additional boards to be connected to the PC. The GUI
can be used to check the wM-Bus communication sample.
and NUCLEO-L152RE boards hosting the ultra-low power STM32.
2.3Board setup
Step 1.Check that the jumper on J1 connector is connected to provide the required voltage to the board
devices.
Step 2.Connect the X-NUCLEO-S2868A1 to the STM32 Nucleo
S2868A1 expansion board connected to an STM32 Nucleo development board
Step 3.Power the Nucleo development board using the Mini-B USB cable
Step 4.Program the firmware in the STM32 on the Nucleo development board using the firmware sample
provided
Step 5.Reset the MCU board using the reset button on the Nucleo development board
Step 6.The evaluation kit is ready-to-use
board as shown in Figure 2. X-NUCLEO-
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3Hardware description and configuration
3.1Interconnection details
The X-NUCLEO-S2868A1 expansion board and the NUCLEO-F401RE or NUCLEO-L152RE board connection
details are listed in the table below
Table 2. X-NUCLEO-S2868A1 and NUCLEO-L152RE connection details (left connector)
NCIOREF
12345678123456
Used to enable different configurations in case a signal conflict occurs when using other expansion board (refer to next
1.
section).
RESE
T
.
Signal name
3
V
3
CN6 PowerCN8 Analog
V
3
V
GNDGNDVINA0A1A2A3A4A5
5
Connector name
Pin number
NUCLEO-L152RE MCU port
X-NUCLEO-S2868A1 expansion board signals
3
GNDGNDGPIO0CSNGPIO1 GPIO2
UM2405
Hardware description and configuration
PA0PA1PA4PB0PC1PC0
GPIO0
GPIO3
(1)
Table 3. X-NUCLEO-S2868A1 and NUCLEO-L152RE connection details (right connector)
D15D14
1098765432187654321
PB8PB9PA5PA6PA7PB6 PC7 PA9 PA8
1.
Optional connection
ARE
GND D13D12D11D10D9D8D7D6D5D4D3D2D1D0
F
CN5 DigitalCN9 Digital
NUCLEO-L152RE MCU port
X-NUCLEO-S2868A1 expansion board signals
GND
SPI_
CLK
1)
SPI_
(
MIS
O
SPI_
MOS
I
SPI_
CSN
3.2SPI and GPIO connection options
The SPI and GPIO connection options between the STM32 and S2-LP can be used to enable dif
configurations in case a signal conflict occurs when using other expansion boards.
Signal name
Connector name
Pin number
(
1)
nS
PB1
PB4 PB5 PB3
0
(
SDN
SDN
1)
nS
(1)
SPI_
CLK
PA1
0
PA2 PA3
ferent
UM2405 - Rev 2
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Current measurement
Table 4. S2-LP interface (optional) with STM32 Nucleo board
S2-LP signalDefault STM32 portOptional STM32 port
GPIO0PA0
CSnPA1
CLKPB3
nSPB4
SDNPA8
PC1
T
o use the optional connection, mount R18, unmount R12
PB6
T
o use the optional connection, mount R9, unmount R13
PA5
T
o use the optional connection, mount R6, unmount R11
PA9
T
o use the optional connection, mount R7, unmount R22
PB10
T
o use the optional connection, mount R19, unmount R10
To use the optional connections, modify the firmware on the basis of the STM32 resources used.
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3.3Current measurement
To monitor the X-NUCLEO-S2868A1 expansion board power consumption, use jumper J1: connect an ammeter
probe between the connector pins 1 and 2 for measurements.
3.4X-NUCLEO-S2868A1 component placement details
The figure below shows the component placement on the X-NUCLEO-S2868A1
The M95640-R is a 64 Kbit serial SPI bus EEPROM with high-speed clock interface. The device can be used to
store the configuration parameters related to S2-LP RF device application or settings.
FeaturesDescription
Order codeM95640-RMC6TG
PackageMLP8
Operating voltage1.8 to 5.5 V
To use the on-board SPI EEPROM, mount R22 resistor on the board.
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4.2S2-LP radio
The X-NUCLEO-S2868A1 expansion board is based on the S2-LP standalone RF transceiver. It operates in the
868 MHz ISM frequency band and wireless M-Bus.
S2-LP narrow band ultra-low power sub-1 GHz transceiver is tuned for 430-470 MHz and 860 - 940 MHz,
frequency bands and programmable RF output power up to +16 dBm.
Order codeS2-LPQTR
PackageQFN24 4x4x1
Operating voltage1.8 to 3.6 V
Table 5. S2-LP details
FeaturesDescription
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page 8/19
Formal notices required by the U.S. Federal Communications Commission ("FCC")
5Formal notices required by the U.S. Federal Communications
Commission ("FCC")
FCC NOTICE: This device complies with part 15 of the FCC Rules. Operation is subject to the following two
conditions: (1) This device may cause harmful interference, and (2) this device must accept any interference
received, including interference that may cause undesired operation.
Changes or modifications not expressly approved by the manufacturer could void the user
the equipment.
Additional warnings for FCC
This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to part
15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a
residential installation. This equipment generates, uses and can radiate radio frequency energy and, if not
installed and used in accordance with the instructions, may cause harmful interference to radio communications.
However, there is no guarantee that interference will not occur in a particular installation. If this equipment does
cause harmful interference to radio or television reception, which can be determined by turning the equipment off
and on, the user is encouraged to try to correct the interference's by one or more of the following measures:
•Reorient or relocate the receiving antenna.
•Increase the separation between the equipment and the receiver.
•Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
•Consult the dealer or an experienced radio/TV technician for help.
’s authority to operate
UM2405
UM2405 - Rev 2
page 9/19
Formal product notice required by the Industry Canada ("IC")
6Formal product notice required by the Industry Canada ("IC")
Innovation, Science and Economic Development Canada Compliance - This device complies with Innovation,
Science and Economic Development RSS standards. Operation is subject to the following two conditions: (1) this
device may not cause harmful interference, and (2) this device must accept any interference received, including
interference that may cause undesired operation. Changes or modifications not expressly approved by the
manufacturer could void the user
Conformité à Innovation, Sciences et Développement Économique Canada - Cet appareil est conforme aux
normes RSS d'Innovation, Science et Développement économique. L'utilisation est soumise aux deux conditions
suivantes: (1) cet appareil ne doit pas causer d'interférences nuisibles, et (2) cet appareil doit accepter de
recevoir tous les types d’interférence, y comprises les interférences susceptibles d'entraîner un fonctionnement
indésirable. Les changements ou les modifications non expressément approuvés par le fabricant pourraient
annuler le permis d'utiliser l'équipement.
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