KB: New Features and Benefits of RSL15

[RSL15 - Knowledge Base]

Key Features

Industry Leading MCU Performance

The RSL15 boasts an Arm Cortex-M33 processor designed specifically for achieving the high performance, power efficient operations required by IoT and embedded solutions.

By combining the features included in the Arm Cotex-M33 core with a number of custom onboard peripherals, the RSL15 is able to achieve top-tier benchmark performance while maintaining operational efficiency.

Ultra-Low Power Operation

Their are several power modes available on the RSL15 hardware that aim to greatly reduce power consumption while maintaining the system responsiveness.

By combing configurable sleep mode behavior (RAM retention, sensor operations, etc) with a minimum deep sleep current of 36nA, the RSL15 enables solutions to achieve a battery-life on the order of years while running on small form-factor batteries.


With growing industry focus on security, there is a clear need for MCUs to support various measure to ensure sensitive data, intellectual property and secure operations are all maintained during the life-time of a device.

To help protect the safety and information that may be directly reliant on the RSL15, it leverages the following security implementations:

  • TrustZone Armv8−M Security Extensions
  • Secure Software Access Control
  • Secure Boot with Root of Trust
  • Secure Lifecycle Management
  • Secure Key Management
  • Application & Data Encryption

Bluetooth Low Energy 5.2 Support

The RSL15 comes equipped with an RF Front-End that is used to implement the physical layer of the Bluetooth Low Energy 5.2 Standard, as well as a certified baseband and protocol stack that enables users to develop Bluetooth Low Energy solutions in an abstract and high-level way.

With new Bluetooth Low Energy features, ranging from Extended & Long-Range Advertising to Localization, the RSL15 makes it possible to implement a wide variety of wireless solutions that fulfill the design requirements of various solutions.

Offerings & Benefits

Comprehensive IDE & Firmware Samples

To compliment the power hardware that is RSL15, we also offer the easy-to-use onsemi IDE and Software CMSIS-Pack that allows users to get the most out their RSL15 experience.

The Eclipse-based onsemi IDE comes preloaded with a number of add-ons that enable a much more simple debugging and development process. These add-ons include: a CMSIS Manager window, a debug window that provides low-level device control via SEGGER J-Link, a hardware register view that allows you to configure the device during runtime, and various other tools to make your life easier.

The RSL15 Software CMSIS-Pack provides users with a variety of sample firmware, compatible with both the onsemi IDE and other industry standard development environments, which demonstrate how users can develop their own firmware to make use of the various hardware offerings of the RSL15. These sample firmware and accompanying documentation allow users to rapidly become familiar with the RSL15 functionality and prepare to develop their own full scale firmware solutions.


RSL15 enables some of the digital and analog peripherals to remain active during low-power mode operations, at the cost of a very low increase to the overall power consumption. We have named this new feature set SmartSense.

This functionality makes the RSL15 perfect for various IoT and wireless applications where reading sensor data and maintain a long-term battery life are critical design concerns.


The onboard Arm CryptoCell−312 acts as a small-form factor add-on that enable many of the security features discussed in the sections above.

Arm TrustZone

The inclusion of the Arm TrustZone enables secure software access control to protect critical software and hardware resources, as well as allowing users to establish a Root of Trust.

The hardware Root of Trust uses the secure boot ROM to authenticate firmware in flash with a certificate−based mechanism using a private−public key scheme. This same mechanism ensures continuity of the hardware Root of Trust after secure Firmware−Over−The−Air (FOTA) update.

Long Range Bluetooth Low Energy

By adding a level of redundancy to the radio packets that are being communicated, the RSL15 is able to recover packet information that may be lost or corrupted during transmission or reception. This new feature allows solutions to work over a longer wireless range, as the error correction will act as a means to ensure the data is proper.

This implementation is extremely beneficial for device designs where the form-factor cannot accommodate a larger antenna or when a higher transmission power cannot be used due to power constraints.

Bluetooth Low Energy Advertising Extensions

The RSL15 has also added support for Bluetooth Low Energy Advertising Extensions. Given the focus on wireless connectivity and low-power operations, the RSL15 is very well suited for beacon implementations, and this features compliments that well.

By allowing the radio to broadcast more information in a single advertising packet, the user is enabled to put even more critical information into their beacon or advertising packet without the need to send a second packet and potentially using more unnecessary power.

Angle of Arrival (AoA) & Angle of Departure (AoD)

Another use-case that benefits from a low-power wireless device is Localization. By using multiple antennas to measure and calculate the difference in time between a transmission reaching each of the antenna (Angle of Departure) or the difference in time between receiving multiple transmissions at a single antenna (Angle of Arrival), the device is able to accurately determine the relative direction between two wireless devices.

When paired with the RSSI measurement capabilities, we are able to determine a relative direction and distance between two devices, effectively offering tracking capabilities within the range offered by Bluetooth Low Energy.

Hardware Configurability (Clocks, Flash Size, Digital I/O, Power)

The RSL15 offers a wide range of hardware configurability to enable users to operate the device in ways that fit their specific needs and use-case.

The following list provides an overview of several of the critical components that users can configure as they see fit:

  • Flexible Clocking and Prescale
  • Two Flash Variants (284 Byte & 512 Byte)
  • Flexible Digital I/O (GPIO, SPI, QSPI, I2C, UART, PWM, PCM)
  • Analog to Digital Converters (High Speed ADC, Low Speed ADC)
  • Flexible Power Management (DC-DC Converter [LDO & BUCK], VBAT of 1.2V - 3.6V)
  • Power Modes (RAM Retention, Wake-Up Sources, Smart Sense)

Additional Details

For More information regarding the features and benefits that the RSL15 provide, please find our RSL15 Datasheet and more at RSL15: Bluetooth® 5.2 Secure Wireless MCU.