Introduction
Electric cars, hybrid cars, and fuel cell vehicles not only help to protect the environment, but they also provide a better quality of
life in urban and rural areas. The innovative, whisper-quiet drive technologies can increase the risk of accidents under certain
circumstances. The acoustic vehicle alerting system (AVAS) provides added safety wherever the noise of electric motors, which
is too quiet, can become a hazard.
The AVAS simulates the engine noise of a combustion engine in the lower speed range to improve the safety of vulnerable road
users (VRUs) such as pedestrians, cyclists, and children. Artificial vehicle sounds are generated using loudspeakers or
actuators through the vibration of the vehicle structural elements proportional to vehicle parameters such as velocity, gas pedal
position, and gear. Electric cars are barely audible, especially at low speeds, and can pose a safety risk. AVAS is a significant
contribution to road safety. If a vehicle with alternative drive technology moves to a higher speed range, the rolling noise of the
tires on the road is sufficient and AVAS is automatically deactivated. AVAS can be fitted not only on passenger cars, but also
commercial vehicles and vehicles such as buses and garbage trucks.
Since July 2021, all new vehicle models registered in the EU must be equipped with an acoustic warning system as a
mandatory requirement under EU Decision ECE R138. If a too-quiet car is traveling in traffic at a speed of less than 20
kilometers per hour, the acoustic warning system must give a signal. At speeds above 20 kilometers per hour, the audible
warning system for electric vehicles automatically deactivates. In the US, the threshold is 19 mph (30 km/h).
Our AEKD-STEREOAVAS is an AutoDevKit acoustic vehicle alerting system (AVAS) demo.
It consists of an AEK-AUD-C1D9031 compact AVAS board, an AEK-MCU-C4MLIT1 domain controller, and two AEK-LCD-
DT028V1 display expansion boards, plus two loudspeakers and a switching button.
The AEK-AUD-C1D9031 communicates with the AEK-MCU-C4MLIT1 via CAN protocol, exchanging commands like start/stop to
simulate alerting sounds used in e-vehicles. The sound is reproduced by the AEK-AUD-C1D9031 ECU through a pair of
integrated loudspeakers.
Two AEK-LCD-DT028V1 boards with resistive touch allow the user to interact with the demo. The first screen shows a graphic
simulation of the tachometer, while the second allows starting/stopping the demo and regulating the sound volume and the
engine rpms.
Warning: The AEKD-STEREOAVAS evaluation kit has not to be used in a vehicle as it is designed for R&D
laboratory use only.
Figure 1. AEKD-STEREOAVAS evaluation kit
Getting started with the AEKD-STEREOAVAS integrated stereo AVAS solution
UM3214
User manual
UM3214 - Rev 1 - July 2023
For further information contact your local STMicroelectronics sales office. www.st.com
