STMicroelectronics Acoustic Vehicle Alerting System with AutoDevKit™

STMicroelectronics Acoustic Vehicle Alerting System with AutoDevKit™ is a solution designed to emit vehicle warning sounds and alert pedestrians to the presence of quiet electric and hybrid vehicles. Quiet vehicles entail risks not to be acoustically detected by pedestrians and cyclists in the lower speed range. The noise emitted by electric and hybrid vehicles can easily be masked by the urban background noise. Therefore, guidelines have been developed in terms of an exterior noise required for detecting Quiet Road Transport Vehicles (QRTV). This solution is designed to address these guidelines.

For all new quiet electric and hybrid vehicles registered from July 2021, an Acoustic Vehicle Alerting System (AVAS) must be enabled to make a continuous noise level of at least 56dBA (within 2 meters) if the car is going 20km/h (12mph) or slower, and a maximum of 75dBA.

Built around an ASIL-B-qualified SPC582B Microcontroller that monitors and controls a Class-D FDA903D power amplifier, this AVAS Solution lets car manufacturers and OEMs offer a customized sound thanks to a flexible sound generation solution, which can simulate engine sounds using WAV audio files. To ensure the warning sounds are heard throughout the entire vehicle's length, even for long vehicles, ST's solution makes it possible to connect two audio amplifiers in a stereo mode fashion, even if both speakers may be playing the same mono sound or two different sounds.

The MCU sends the audio samples to the amplifier via a simulated I²S bus, while its I²C interface is used to program the FDA903D amplifier, ensuring modularity. Handling the signal conditioning and processing, the L9616 high-speed bidirectional transceiver, placed on the connector board of the MCU and the audio amp, can be used for remote control of the audio systems via the vehicle's CAN interface.

Solution Evaluation KIt

The Acoustic Vehicle Alerting System (AVAS) with AutoDevKit consists of an SPC582B MCU Discovery Board (AEK-MCU-C1MLIT1), a Class-D Automotive Audio Amplifier Evaluation Board (AEK-AUD-D903V1), and the necessary speakers.

The SPC58 2B MCU Discovery board monitors and controls the FDA903D power amplifier on the AEK-AUD-D903V1 board via I²C and I²S serial interfaces and GPIOs. The MCU board and the audio amplifier board can be wired together directly or via a Connector Board (AEK-CON-C1D9031) designed to simplify the process of hosting L9916 transceivers and sliders to test volume and engine rpm sound changes.

The same functionality can now be found in a single, integrated board (AEK-AUD-C1D9031).

Key Product Benefits

SPC582B60E1: Dedicated Automotive-Grade 32-Bit Microcontroller
Part of the SPC58 Chorus microcontroller series, the SPC582B60E1 benefits from the comprehensive SPC5 development ecosystem. Designed in compliance with ISO 26262 specifications, SPC582B Line MCUs support the ASIL-B safety standard and feature a high number of ISO CAN-FD channels as well as numerous power and performance enhancements.
FDA903D: Single-Bridge Class-D Power Amplifier
Integrating a high-performance D/A converter with powerful MOSFET outputs, the FDA903D is a very compact, powerful power amplifier with outstanding efficiency performance (90%). With a very wide operating range, it comes with a complete diagnostics array specifically designed for automotive applications.
L9616: High-Speed CAN Bus Transceiver
Supporting data rates of up to 1 Mbaud using either shielded or non-shielded lines, the L9616 features adjustable slope control to reduce RFI and EMI for improved sound quality and enhanced signal protection.

Features

Low-cost, entry-level AVAS solution
Possibility to use two different modules playing two different speakers
Real-time monitoring control features both in play and mute mode
Scalable solution (possibility to select different MCUs with dedicated demo)
Accessible also for entry-level users providing ready-to-use drivers source code

Software

The AVAS Solution Evaluation Kit is fully supported by a complete software ecosystem, which includes the SPC5Studio development environment, SPC5 debugging software for Windows (SPC5-UDESTK-SW), and the AutoDevKit Library Plugin (STSW-AUTODEVKIT) for SPC5Studio containing the FDA903D power amplifier driver as well as sample application code.