UM2641
User manual
Getting started with the X-NUCLEO-S2915A1 Sub-1 GHz 915 MHz RF expansion
board based on S2-LP radio for STM32 Nucleo
Introduction
The X-NUCLEO-S2915A1 expansion board is based on the S2-LP radio and operates in the 915 MHz ISM frequency band.
The expansion board is compatible with ST morpho and Arduino UNO R3 connectors.
The X-NUCLEO-S2915A1 interfaces with the STM32 Nucleo microcontroller via SPI connections and GPIO pins. Y
change some of the GPIOs by mounting or removing the resistors.
Figure 1. X-NUCLEO-S2915A1 expansion board
ou can
UM2641 - Rev 1 - November 2019
For further information contact your local STMicroelectronics sales of
fice.
www.st.com
1 Acronyms and abbreviations
Table 1. List of acronyms
Acronym Description
AMR Automatic meter reading
EEPROM Electrically erasable programmable read only memory
GHz Giga Hertz
GUI Graphical user interface
LED Light emitting diode
MCU Microcontroller unit
P2P Point-to-point communication
RF Radio frequency communication
SPI Serial peripheral interface
USB Universal serial bus
wM-Bus Wireless metering bus
WSN Wireless sensors network
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Acronyms and abbreviations
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2 Getting started
2.1 Overview
The X-NUCLEO-S2915A1 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 +27 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
• Sigfox compatible
• Sample firmware for P2P communication
• 6LoWPAN compatible thanks to STM32Cube
• FCC ID: S9NS2915A
• IC ID: 8976C-S2915A1
• RoHS and WEEE compliant
UM2641
Getting started
2.2 Typical applications
The X-NUCLEO-S2915A1 expansion board can be used for the evaluation of the S2-LP device in multiple
applications:
•
wM-Bus application
• Point-to-point communication protocol
• 6LoWPAN applications
• SigFox communication
You can develop other applications for evaluating the devices, such as:
• Automatic meter reading
• Home and building automation
• WSN
• Industrial monitoring and control
• Wireless fire and security alarm systems
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2.3 Hardware and software requirements
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Hardware and software requirements
To use STM32 Nucleo development boards with the X-NUCLEO-S2915A1
as shown below.
Figure 2. X-NUCLEO-S2915A1 expansion board connected to an STM32 Nucleo development board
expansion board, connect the boards
The interconnection between the STM32 Nucleo and the X-NUCLEO-S2915A1 has been designed to allow using
any STM32 Nucleo board, although complete testing has been performed using NUCLEO-L053R8, NUCLEO-
F401RE and NUCLEO-L152RE boards hosting the ultra-low power STM32.
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 protocol.
2.4 Board setup
Step 1. Check that the jumper on JP1 connector is connected to provide the required voltage to the board
devices.
Step 2. Connect the X-NUCLEO-S2915A1 to the STM32 Nucleo
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.
The evaluation kit is ready-to-use.
board.
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Hardware description and configuration
3 Hardware description and configuration
3.1 Interconnection details
The X-NUCLEO-S2915A1 expansion board and the NUCLEO-F401RE or NUCLEO-L152RE board connection
details are listed in the table below
Table 2. X-NUCLEO-S2915A1 and NUCLEO-L152RE connection details (left connector)
NC IOREF RESET 3V3
CN6 Power CN8 Analog
1 2 3 4 5 6 7 8 1 2 3 4 5 6
3V3 GND GND GPIO0 CSN GPIO1 GPIO2
5
.
Signal name
V
GND GND VIN A0 A1 A2 A3 A4 A5
Connector name
Pin number
NUCLEO-L152RE MCU port
PA0 PA1 PA4 PB0 PC1 PC0
X-NUCLEO-S2915A1 expansion board signals
GPIO0
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(1)
GPIO3
Optional connection.
1.
Table 3. X-NUCLEO-S2915A1 and NUCLEO-L152RE connection details (right connector)
Signal name
D15 D14 AREF GND D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
Connector name
CN5 Digital CN9 Digital
Pin number
10 9 8 7 6 5 4 3 2 1 8 7 6 5 4 3 2 1
NUCLEO-L152RE MCU port
PB8 PB9 PA5 PA6 PA7 PB6 PC7 PA9 PA8 PB10 PB4 PB5 PB3 PA10 PA2 PA3
X-NUCLEO-S2915A1 expansion board signals
SCL SDA GND
Optional connection.
1.
SPI_C
(1)
LK
SPI_MISOSPI_M
OSI
SPI_C
(1)
SN
nS
(1)
SDN
SDN
(1)
nS
SPI_
CLK
3.2 SPI and GPIO connection options
The SPI and GPIO connection options between the STM32 Nucleo and S2-LP can be used to enable different
configurations in case a signal conflict occurs when using other expansion boards.
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Table 4. S2-LP interface with STM32 Nucleo board
S2-LP signal Default STM32 port Optional STM32 port
CSn PA1
PB6
T
o use the optional connection, mount R9, unmount R13
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Current measurement
S2-LP signal Default STM32 port Optional STM32 port
CLK PB3
nS PB4
SDN PA8
PA5
T
o use the optional connection, mount R6, unmount R11
PA9
T
o use the optional connection, mount R7, unmount R19
PB10
T
o use the optional connection, mount R18, unmount R10
To use the optional connections, modify the firmware on the basis of the STM32 resources used.
T
able 5. SKY66420 power amplifier settings
SKY66420 SW1 SW2
LNA ON (default)
LNA OFF
100 pF capacitor between pin1 and pin2 (pin1 and
pin3 open)
100 pF capacitor between pin1 and pin3 (pin1 and
pin2 open)
100 pF capacitor between pin1 and pin3 (pin1 and
pin2 open)
100 pF capacitor between pin1 and pin2 (pin1 and
pin3 open)
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Table 6. SKY66420 interface with STM32 Nucleo board
SKY66420 signal Default STM32 port Optional STM32 port
GPIO0 PA0
GPIO1 PA4 N.A.
GPIO2 PB0 N.A.
T
o use optional connection mount R25, unmount R12
3.3 Current measurement
To monitor the X-NUCLEO-S2915A1 expansion board power consumption, use jumper J1: connect an ammeter
probe between the connector pins 1 and 2 for measurements.
3.4 X-NUCLEO-S2915A1 component placement details
The figure below shows the component placement on the X-NUCLEO-S2915A1 expansion board.
PC1
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