Electric Vehicle Warning Sound System: Page 4 of 4

July 08, 2020 //By Andreas Pellkofer, Jagannath Rotti, Danny Ko, Analog Devices
Electric Vehicle Warning Sound System
Since electric vehicles do not emit the sound pedestrians and other traffic participants need to get alerted, the legislators all over the world stipulates that electric vehicles must be equipped with appropriate electronic noise generators. This article presents an elegant and easy to implement solution.

Audio Mixing in Slew

For audio mixing, configure the various gains with respect to vehicle speed.

Playback of WAV Files

Although the required WAV files are present in flash, the user can play or stop some of the WAV files, depending on the dynamic conditions.

SigmaDSP-Based Solution

For entry-level applications, an ADAU1450 SigmaDSP processor can be used as an alternative to the ADSP-BF706 processor. For evaluation purposes, the EVAL-ADAU1452 evaluation board can be used.

Figure 5 shows the different processing blocks inside the SigmaDSP processor.


Figure 5. Processing blocks on SigmaDSP processor

The following software requirements are supported in the ADAU1450 using the SigmaStudio programming environment:

  • Multiple tone generation

  • Dynamic volume control with up to 64 ranges

  • Sound mixing

  • Limiter

  • Pitch shifting that increases audio pitch as speed increases

  • Simultaneous playback of up to 5 WAV files from the SPI flash memory

Analog Devices provides an engine sound simulator module in SigmaStudio to simplify engine sound tuning and reduce the number of external, simultaneous WAV files required. The engine sound simulator can internally generate up to 32 harmonics. The order and amplitude of these harmonics can be programmed through the graphical user interface (GUI).

The harmonic generator module is available as part of the ESS Toolbox. It can be downloaded directly from the SigmaStudio download page (Rev 4.4. upward). Note that SigmaStudio cannot support a CAN software stack, and an external microprocessor is required.

SigmaStudio

SigmaStudio is a graphical programming environment originally designed for the SigmaDSP portfolio of processors. This software has a built in library of algorithms developed specifically for automotive applications. The GUI simplifies the tuning process and provides controls and filter coefficients that can be varied on the fly without the requirement for writing code. SigmaStudio can be downloaded from the SigmaStudio page on the Analog Devices website.

Conclusion

Analog Devices offers comprehensive solutions for an entry-level system and for an advanced engine sound system that supports in-cabin engine sounds and external engine sounds. This article aims to ease the decision making process for the user, as well as reduce user time to market. Analog Devices offers a complete system solution, including the necessary software components for rapid prototyping and product development.

About the Authors:

Andreas Pellkofer graduated from Technical University of Munich in electronic and information technology. He joined Analog Devices 2006 as an applications engineer working with the Blackfin processor family. Later he mainly dealt with automotive customers for DSPs. In 2013 he moved into a system engineer role in the Digital Video Products Group, focusing on video transport and camera systems for automotive. In 2018 he became part of the Emerging Systems and Technologies Group working on in-cabin vital sign monitoring and hands-on detection solutions. He can be reached at andreas.pellkofer@analog.com.

Jagannath Rotti graduated from PES Institute of Technology, Bangalore with a degree in electronics and communication. He has 13 years of automotive software experience. Prior to joining Analog Devices, he worked at Robert Bosch and Autoliv in the powertrain and safety domains, respectively. At ADI, he is a software lead in the Automotive SW Team, mainly working in cabin electronics in general and automotive audio buses. His areas of interest include automotive networks, network security and cryptography, audio algorithms, autonomous driving, sensor fusion, and Sanskrit literature. He can be reached at jagannath.rotti@analog.com.

Danny Ko is an automotive system applications engineer for audio and emerging technologies based in Seouål, Korea. Danny joined ADI in 2004 as a DSP FAE supported Samsung, LG, and broad market for three years before changing his focus to automotive in 2007. In 2010, Danny transferred to the automotive segment as an automotive system application engineer and worked in the infotainment area, primarily in audio applications. Since 2018, his work has extended to emerging technology. He can be reached at danny.ko@analog.com.

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