A regulator and a level translator are employed to adjust level of a debug signal coming from the audio amp for current monitoring during play. This signal is called I2S test and it is digital and synchronized with the audio data sent through the I2S interface.
To make the system a potential audio sub-module, a CAN transceiver has been added employing L9616. This allows to sent audio commands to the MCU through CAN interface. A 6-pin male connector is available on the board for this purpose.
The last 4-pin plug of the board is dedicated to connect a separate board with two potentiometers actuated with sliders. The values of the potentiometers are fed to the MCU ADCs (analog-to-digital converters) compatible with 5V levels. One potentiometer could be employed to control the volume while the second one is used to accelerate the sound played.
Traditionally, the audio sub-module is used for typical automotive infotainment applications. Recently, the Electric Vehicle Warning Sounds (AVAS) system has become a new growing application for automotive audio. This system is required by new vehicles to alert pedestrians of the presence of electric powered vehicles that are generating much less noise. Warning sounds may be driver triggered (like a horn) or automatic mimicking engine sounds.
The speed slider can be employed to modify the played sound to simulate a change of the engine rpm. From 2021 according to government regulations, the vehicle 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. The combination of AEK-AUD-D903V1 with AEK-MCU-C1MLIT1 through AEK-CON-C1D9031 offers a viable low-cost solution for entry-level AVAS systems. The CAN interface allows remote control of several audio sub-modules that can be placed around the vehicle.