Renesas Electronics Corporation
Search

Sensor Transmission Over Bluetooth Low Energy

Overview

Build Smart Sensor Products with Real-Time Bluetooth Connectivity

Accelerate the development of connected sensor products with a ready-to-evaluate project that acquires live 3-axis motion data and transmits it to a Bluetooth Low Energy (LE) client. The solution combines the Renesas RA6E2 MCU, a DA14531 Bluetooth LE module, and an ICM42670 motion sensor in a modular prototype designed for rapid evaluation and reuse.

The reference application uses interrupt-driven sensing, configurable data filtering, and (GATT Generic Attribute Profile) notifications to deliver responsive sensor telemetry without a fixed polling loop. A connected client can also adjust the sensor output data rate at runtime, helping developers explore the balance between responsiveness, data volume, and power-oriented system behavior.

Solution

Build Connected Motion-Sensing Applications with Confidence

The sensor data transmission over Bluetooth LE solution project provides a complete reference implementation for capturing accelerometer data and publishing it over Bluetooth LE. An FPB-RA6E2 board acts as the host and processing platform and the ICM42670 sensor connects over I²C and signals new samples through a data-ready interrupt. Meanwhile, a DA14531 module provides Bluetooth LE connectivity through a UART-based Generic Transport Layer interface.

The application separates acquisition and communication into two FreeRTOS threads. The sensor thread owns I²C, converts measurements to milli-g, and applies the publish policy. The Bluetooth LE thread owns the wireless interface and sends the latest accepted sample as a GATT notification. A second GATT characteristic allows the connected client to request a new sensor output data rate from 12Hz to 1600Hz. 

Sensor Transmission Over BLE Solution Block Diagram.

How it Works

Number 1 within a blue circle.
Acquire Motion Data

The ICM42670 data-ready signal triggers acquisition. The RA6E2 reads the 3-axis acceleration sample over I²C and converts the values to milli-g.

Number 2 within a blue circle.
Apply the Publish Policy

The sensor thread applies a notification-rate limit and a minimum-change threshold, with optional smoothing available in the project configuration.

Number 2 within a blue circle.
Hand Off the Latest Sample

An event-group signal wakes the Bluetooth LE thread while keeping sensor-bus access isolated from wireless processing.

Number 4 within a blue circle.
Transmit Over Bluetooth LE

After the client subscribes, X, Y, and Z acceleration values are sent through a custom sensor data characteristic using GATT notifications.

Number 5 within a blue circle.
Adjust the Sensor Rate

As required, the client can write a 2-byte output-data-rate value to a control characteristic. The sensor thread validates and safely applies the new rate.

Customer Benefits

  • Start from a complete, working sensor-to-Bluetooth LE reference project instead of integrating each subsystem from scratch.
  • Evaluate live wireless sensor telemetry with readily available modular hardware.
  • Reduce unnecessary Bluetooth LE traffic through threshold-based and rate-limited notifications.
  • Change the sensor sample rate from the connected client during evaluation.
  • Reuse a clear software interface for additional sensor types and data fields.
  • Accelerate the path from technology evaluation to an application-specific prototype. 

Software Components

ComponentsPurpose
Sensor Data Acquisition over I²CInitializes the ICM42670, handles the data-ready interrupt, reads 3-axis acceleration, and converts samples to milli-g.
Sensor Data Processing and Publish PolicyApplies notification-rate limiting, a minimum-change threshold, and optional smoothing before data is handed to Bluetooth LE.
Bluetooth LE Sensor Data Transmission Transfers the latest accepted sample to the BLE thread and sends the custom GATT notification when a client is connected and subscribed.
Bluetooth LE Sensor Rate ControlReceives a runtime output-data-rate request from the client, validates the requested value, and defers sensor reconfiguration to the sensor thread.
Bluetooth LE GATT ServicesImplements the Sensor Data Notify characteristic, its client configuration descriptor, and the Sensor ODR Write characteristic.
Renesas FSP and FreeRTOS IntegrationProvides peripheral configuration, middleware integration, thread scheduling, and event-group communication for the reference application.

Applications

The reusable sensor-to-Bluetooth LE data path can support motion-aware and telemetry-driven products across multiple markets, including:

Industrial

Asset & Equipment Monitoring
Appliances
Building Automation

Consumer Electronics

Wearables
 
 
Xplore tool sensor transmission over Bluetooth low energy UI screenshot.

Get Started

Xplore assets are delivered through Renesas 365, connecting hardware, software, documentation, and technical resources in one environment to accelerate development from exploration to prototype.

Experience in Renesas 365

Documentation

Featured Hardware

Fast Prototyping Board for RA6E2 MCU Group

FPB-RA6E2 Active

Low-Power Bluetooth Pmod Board (Renesas QuickConnect IoT)

US159-DA14531EVZ Active

ICM-42670-P 6-Axis Gyroscope and Accelerometer Pmod Daughter Card

QCIOT-ICM42670POCZ Active