Renesas RE01 256KB Group: Ultra-Low Consumption Voice Recognition & Bluetooth Application Note

Introduction

Conventional voice recognition devices often require AC power. The ultra-low power RE family enables voice recognition remote controls and wearable device user interfaces that can run for extended periods on small batteries without external power sources. This application note details sample code combining voice recognition using RECAIUS™ Speech recognition middleware (Voice Trigger), Bluetooth communication, and RGB light sensor processing.

Target Device

RE01 256KB Group

RECAIUS™ Speech recognition middleware Voice Trigger is a product of Toshiba Digital Solutions Corporation, referred to as Voice Trigger herein. RECAIUS™ is a registered trademark or trademark of Toshiba Digital Solutions Corporation in Japan and other countries. Bluetooth® is a registered trademark or trademark of Bluetooth SIG, Inc. USA, referred to as Bluetooth herein.

1. Specifications

1.1 Description of Sample Code

This application note describes sample code that integrates voice recognition (Voice Trigger), Bluetooth communication, and RGB light sensor processing. In voice recognition mode, the system recognizes voice input from a microphone, mimicking hands-free operation in smartwatches or smart glasses, and displays relevant information on an LCD based on detected words. The RGB light sensor mode serves as an example of sensor processing in IoT edge devices, calculating illuminance and outputting it via the LCD and BLE communication.

1.1.1 Menu Selection

The APP_SET (SW2) and APP_MODE (SW1) buttons are used to select a demo from the menu. Available menus are "Voice" and "Brightness".

• APP_SET (SW2): Confirms the selection (initiates the demo with a triangle on the left edge).
• APP_MODE (SW1): Selects the next demo (moves the left triangle).

Figure 1 illustrates the menu screen, and Figure 2 shows the button positions on the board.

Figure 1: Menu screen showing options like Voice, Brightness, and Battery status.

Figure 2: Photograph of the development board highlighting the APP_SET and APP_MODE buttons.

1.1.2 Voice: Voice Recognition Mode

Selecting "Voice" from the menu transitions the demo to voice recognition mode. In this mode, Voice Trigger processes voice input via the microphone. The recognized word or phrase determines the information displayed on the LCD. The speech recognition result is also transmitted via Bluetooth to a tablet PC running a Renesas-provided Android app.

Figure 3: Diagram illustrating the voice recognition process, from initial screen to voice input, processing, and output of results to LCD and Tablet PC.

1.1.3 Brightness: RGB Light Sensor Mode

When "Brightness" is selected, the demo calculates illuminance from data acquired by the RGB light sensor and displays it on the LCD. The illuminance value is also transmitted via Bluetooth and shown as a time-series graph on a tablet PC running a Renesas Android app.

Figure 4: Diagram showing the operation in RGB light sensor mode, illustrating brightness measurement and graph display.

1.2 Pins Used

Table 2 lists the pins utilized by this sample code.

2. Operating Conditions

The sample code's operation has been tested under the conditions specified in Table 3.

3. Description of Software

3.1 System Configuration Diagram

Figure 5 presents a system configuration diagram.

Figure 5: System Configuration Diagram showing the interaction between MIC Module, RGB Light Sensor, RE01 256KB microcontroller, Bluetooth Module, and Tablet PC.

3.2 Software Structure

The sample code's structure is illustrated in Figure 6.

Figure 6: Software Structure diagram depicting the layered architecture: Application Layer, Middleware Layer, and Driver Layer.

3.3 Flowchart

Figure 7 provides the application's flowchart.

Figure 7: Flowchart detailing the operational sequence, including power-on, menu selection, voice recognition, and brightness measurement modes, along with key input handling and transitions.

3.4 Clock Settings for each Mode

The application layer manages clock and operating modes during each demo operation to minimize current consumption. Clock and operation modes are managed by the application layer during operation and menu control standby. The middleware layer manages these during demo control standby. Table 4 shows clock and operation modes during operation, with "menu control" being the basic state.

During periods like AD conversion or waiting for user action, the software transitions to a low-power mode (Sleep) to reduce current consumption. Table 5 shows clock and operation modes during waiting periods.

3.5 Current Consumption

Table 6 details the power consumption for each operation mode.

4. Get Sample Code

Renesas provides sample code for the RE01 256KB along with an Android app for tablet PCs. For inquiries, please contact your local Renesas Electronics sales office or distributor via www.renesas.com/contact/.

5. Reference Documents

User's Manual: Hardware

• RE01 1500KB Group User's Manual Hardware R01UH0796
• RE01 256K Group User's Manual Hardware R01UH0894
• (The latest versions can be downloaded from the Renesas Electronics website.)

RE01 1500KB, 256KB CMSIS Package Startup Guide

• RE01 1500KB, 256KB Group Startup Guide to Development Using CMSIS Package R01AN4660
• (The latest version can be downloaded from the Renesas Electronics website.)

Technical Update/Technical News

• (The latest version can be downloaded from the Renesas Electronics website.)

User’s Manual: Development Tools

• (The latest version can be downloaded from the Renesas Electronics website.)

For more information about Voice Trigger, please contact Toshiba Digital Solutions Corporation at https://www.toshiba-sol.co.jp/en/contact/index.html.

Revision History