Ultra-Low-Power KNX-RF Radio Transceiver For Energy-Saving Wireless Applications in Building Automation

S2-LP Transceiver by STMicroelectronics
S2-LP Transceiver by STMicroelectronics
S2-LP Transceiver by STMicroelectronics

STMicroelectronics has announced the release of high-performance S2-LP ultra-low-power KNX-RF radio transceiver intended for RF wireless applications in the sub-1 GHz band. Enabling energy-saving standardized wireless connectivity for smart-building controls, the transceiver is designed in such a way that it can operate in both the license-free ISM and SRD frequency bands at 433, 512, 868, and 920 MHz. Moreover, it can also be programmed to operate at other additional frequencies in the 413-479 MHz, 452-527 MHz, 826-958 MH, 904-1055 MHz bands.

The transceiver runs on an STM32 microcontroller (MCU) or on a BlueNRG-2 Bluetooth Low Energy System-on-Chip (SoC) that embeds an Arm Cortex-M0 core running at 32MHz and a comprehensive set of I/O peripherals. It supports different modulation schemes viz. 2(G)FSK, 4(G)FSK, OOK and ASK. The air data rate is programmable from 0.1 to 500 kbps. It includes a certified KNX-RF stack, RF adaptation layer, and S2-LP library needed to connect the transceiver to create an ultra-low-power wireless KNX node.

S2-LP operates in the 868.3MHz band at 10mA with +10dBm output and delivers market-leading energy-efficient, secure, and robust wireless connectivity, hence, prolonging battery run-time and reducing the overall cost of the solution. It can be used in systems with channel spacing down to 1 kHz enabling the narrow band operations. The S2-LP shows an RF link budget higher than 140 dB for long communication ranges and meets the regulatory requirements applicable in territories worldwide, including Europe, Japan, China, and the USA.

With the blend of S2-LP radio and BlueNRG-2 SoC, a unique hybrid and low-power optimized KNX/Bluetooth solution in two chips is created. This enables smartphones to access KNX-based networks and provides an intuitive and stylish interface for conveniently monitoring, controlling, configuring, provisioning, and updating the KNX nodes. The KNX-RF software enables innovation and power savings for push-buttons, light switches, occupancy sensors, roller-shutter controls, dimmer actuators, and other devices for lighting, heating, HVAC, and energy-harvesting systems.

The software meets the latest KNX-RF Multi specification, which supports secure (S mode), encrypted communications, and frequency agility with five channels to help avoid interference and permit fast and slow communication modes to save power. The features that the transceiver comes endowed with ensure to boost reliability and allow larger numbers of KNX devices to coexist on the network, including listen before talk (LBT), fast acknowledge with auto-retry, and support for repeaters.


Features of S2-LP Transceiver

  • Modulation schemes: 2(G)FSK, 4(G)FSK, OOK, ASK\
  • Frequency bands: 413-479 MHz (S2-LPQTR), 452-527 MHz (S2-LPCBQTR), 826-958 MHz (S2-LPQTR), 904-1055 MHz (S2-LPCBQTR)
  • Ultra-low power consumption: 7 mA RX, 10 mA TX @ +10 dBm
  • Programmable RF output power up to +16 dBm
  • More than 145 dB RF link budget
  • 4-wire SPI interface
  • Fully integrated ultra-low power RC oscillator
  • Wireless M-BUS supported
  • KNX-RF supported
  • Enables operations in the SIGFOX and MONARCH networks


Note: More technical information can be found in the S2-LP datasheet linked at the bottom of this page and on the S2-LP Transceiver product page.

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