Bluetooth Low Energy MCU provides integrated solution for smart connected devices


RSL15 from onsemi protects connected devices with a comprehensive set of advanced security functions including TrustZone® support and root-of-trust

The RSL15 from onsemi, a secure low-power wireless microcontroller which implements Bluetooth® Low Energy 5.2 networking, provides a complete set of control and connectivity functions for smart devices in industrial and medical applications.


Based on an Arm® Cortex®-M33 processor core, the RSL15 features built-in power management, a wide supply-voltage range suitable for coin cells, a flexible set of GPIOs, and an extensive set of peripherals. The RSL15 includes 80 kbytes of RAM. Flash memory options are 284 kbytes or 512 kbytes.


The RSL15 is backed by a comprehensive but easy-to-use software development kit (SDK) which provides sample applications to demonstrate the MCU’s hardware capabilities. Other features of the SDK include a cybersecurity platform, a low-power Smart Sense mode for acquiring sensor data, and tools for configuring the power management functions and to select Bluetooth Low Energy features.


onsemi has ensured that connected devices based on the RSL15 are safe from cyber-attack. The RSL15 provides a comprehensive mix of security capabilities, including Arm TrustZone technology, which provides trusted execution environments for at-risk peripherals and functions. The RSL15 also features Arm CryptoCell™-312 technology to provide root-of-trust and additional security mechanisms such as:

  • True random number generator
  • Standard encryption accelerators
  • Support for a wide range of encryption algorithms, including:
    • AES 128/192/256
    • SHA
    • Support for public key infrastructure
    • Elliptic curve cryptography
    • Message authentication
  • Secure boot embedded in hardware ROM
    • Hardware-based root-of-trust using secrets stored in dedicated hardware
    • Managed life cycle model
  • Secure key storage
  • Secure debug controlled with certificates

The RSL15 supports capabilities provided by the Bluetooth 5.2 specification, including long range, higher data transmissions, and localization through detection of the angle of arrival and angle of departure of wireless transmissions.


The low power consumption of the RSL15 has been verified by the Embedded Microprocessor Benchmark Consortium. The MCU achieved a score of 60.5 on its ULPMark™-CoreMark benchmark in the performance category, the best in its class. On the ULPMark-CoreProfile benchmark, which calculates the deep-sleep efficiency of MCUs, the RSL15 holds second place, only behind the onsemi RSL10 wireless MCU.


  • Bluetooth Low Energy 5.2 certified:
    • Up to 10 simultaneous connections
    • Long range
    • 2 Mbits/s transceiver
    • Extended advertising
    • Backwards compatibility with earlier Bluetooth specifications
  • 36 nA sleep mode current
  • 2.7 mA peak Receive current at 1 Mbit/s
  • 4.3 mA peak Transmit current at 0 dBm output power
  • -94 dBm sensitivity at 2 Mbits/s data rate
  • Configurable output-power range: -17 dBm to +6 dBm
  • Supply-voltage range: 1.2 V to 3.6 V


  • Industrial automation and sensing
  • Connected medical sensors
  • Wearable devices
  • Asset tracking
  • Electronic tags
  • Access control
  • Electronic labels
  • Data loggers
  • Smart appliances
  • Energy-harvesting switches
onsemi — RSL15 Secure Wireless Microcontroller

Evaluation Board

Board Part Number: RSL15-EVB

The RSL15-EVB evaluation and development board is intended to be used with the onsemi integrated development environment. It enables evaluation of the RSL15, and development of software applications for the device.

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