Solution Description
Designed to emit vehicle warning sounds and alert pedestrians to the presence of electric drive vehicles, Acoustic Vehicle Alerting Systems (AVAS) must make a continuous noise level of at least 56 dBA (within 2 meters) if the car is going 20 km/h (12 mph) or slower, and a maximum of 75 dBA for all new quiet electric and hybrid vehicles registered from July 2021.
Built around an SPC58 2B line microcontroller that monitors and controls a Class-D FDA903D power amplifier, our AVAS solution lets car manufacturers and OEMs offer a customized sound thanks to a flexible sound generation solution able to simulating 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 speaker may be playing the same mono sound or two different sounds.
Our solution is based on an ASIL-B qualified SPC582B line microcontroller that monitors and controls one or more Class-D FDA903D power amplifiers driving the loudspeakers. 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.
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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, SPC58 2B 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 together 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.
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All Features
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- 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
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