A breakthrough in domestic in-vehicle audio bus chips to meet the upgraded audio needs of smart cockpits

In recent years, car cockpit audio systems have received more and more attention. Electric vehicles have broken the previous restrictions on the use of electrical equipment in fuel vehicles when parked, and have also spawned more car-use environments, including camping, resting, and cockpit entertainment. These changes have led to the emergence of audio systems with greater peak power, and better audio systems have been continuously sinking to mid- and low-priced models. For example, the newly launched Xiaopeng MONA M03 is equipped with an 18-speaker audio system at a price of around 120,000 yuan. In the audio system, a large number of chip products

are also needed , including audio bus chips. Recently, New Coastline announced the launch of the first domestically produced in-vehicle audio bus chip, successfully achieving domestic substitution and breaking the exclusive monopoly of international manufacturers. What is the role of the in-vehicle audio bus chip? The traditional in-vehicle audio system adopts a point-to-point mode, with a complex system and many cables. This can also be seen in the past wired home theater. Each speaker needs to be connected to the power amplifier, so multiple cables need to be extended. In the car audio system, with the development of the smart cockpit, not only the number of speakers in the audio system is increasing, but the voice function also brings multiple microphones in the whole vehicle hardware , and even the active noise reduction in the cockpit also requires some microphones that receive noise. Therefore, the demand for various microphones to transmit signals has increased greatly. The previous point-to-point mode will cause the number of wire harnesses used to increase, increase the weight and cost of the whole vehicle, and occupy the cockpit space. In terms of transmission technology, the traditional car audio system uses analog signal transmission, which is susceptible to interference during the transmission process, has high latency, and the weight of the wire harness is also large. Therefore, many smart cockpits currently use audio bus chips to reduce the number of wire harnesses, latency, and system complexity through digital transmission. In order to solve the problems of complex wiring harnesses and audio delay, a digital audio bus is needed to ensure the quality of data transmission while reducing the complexity and number of wiring harness connections to reduce costs. Of course, corresponding chips are also needed to support this proprietary audio bus technology for signal transmission and processing, which is the audio bus chip. Domestic replacement of audio bus chips There are not many audio bus chips on the market. Specifically, ADI 's A2B ( Automotive Audio Bus) solution is basically used. A2B is a single-master, multi-slave system. The transceiver chip in the master controller is used as the master and supports up to 16 slave nodes. The master node generates clock , synchronization and framing for all slave nodes. The master A2B transceiver chip can be programmed through the control bus ( I2C ) for configuration and readback. According to ADI , the master-slave node topology of A2B is inherently more efficient than existing digital bus architectures. After starting a simple bus initialization process, the bus can operate normally without further processor intervention. An additional advantage of A2B's unique architecture is that the system delay is completely deterministic (less than 50 µs) and the delay is independent of the position of the audio node on the A2B bus. This feature is extremely important for voice and audio applications such as ANC/RNC and ICC , where audio samples from multiple remote sensors must be processed in a time-consistent manner. At the same time, on the wiring harness, all A2B transceivers can transmit audio, control, clock and power supply signals on a single unshielded twisted pair , which can effectively reduce the number of cables and lower the cost. Similar to A2B, the in-vehicle audio bus chip launched by Newport Coast this time uses a high-bandwidth digital link, which can use a low-cost unshielded twisted pair to connect various devices such as microphones, amplifiers , speakers, digital signal processors, audio ECUs, sensors, etc. Audio bus technology can achieve excellent audio quality and build a more feature-rich in-vehicle audio system, while having significant advantages such as low latency, low cost, low weight, and low system complexity. In order to quickly introduce applications, it is said that the New Coast audio bus chip can also achieve Pin -to-Pin compatibility with international manufacturers' products, and samples have been sent to leading OEMs and Tier1. Summary: With the development of smart cockpits, the audio bus will usher in a new round of rapid technology iteration. From the iterations of ADI's A2B transceivers in recent years, we can see that the maximum number of sub-nodes supported in 2021 is only 10, while the latest products currently support 16. Therefore, for some digital-analog hybrid chip manufacturers, the in-vehicle audio bus may be a good track.