From a software perspective, a DSP chip is divided into three layers. Our whole machine manufacturer adopts the user layer.
    If the software is powerful enough, the application layer CAN be enabled. You can write and insert software and plugins by yourself, and combine them with the in-vehicle CAN or even AI to form a more powerful control, adjustment and processing function.
1-User layer
    The specific functions such as adjusting EQ, gain, phase, mode, etc. provided by DSP chip manufacturers, as well as the interface part, usually belong to the user layer.
    Such functions are often implemented through configuration tools, parameter interfaces or simple instruction sets. Users do not need to write complex code; they can complete the operation simply by adjusting parameters (such as sliders and numerical input), with a greater emphasis on "convenient interaction", which conforms to the user layer's characteristics of "lowering the usage threshold and directly facing user operation".
    Of course, if these adjustment functions need to be implemented through programming by calling API interfaces, they may be classified at the application layer. However, in practice, such parametric adjustments are more often categorized at the user layer.
2-Application Layer
     The application layer requires customers to program and develop based on the interfaces provided by the chip and in combination with their specific business scenarios (such as signal processing algorithms, device control logic, etc.). It may involve complex functional implementations (such as signal filtering with high real-time requirements, protocol adaptation, etc.), and customers need to have certain programming and algorithm capabilities.
    The user level is more inclined towards "operational convenience", mostly involving configuration tools, visual interfaces or simple parameter adjustments. Customers can complete these tasks by clicking or filling in parameters, etc. The requirement for professional programming skills is relatively low, and the entry threshold is also lower.
    Simply put, the application layer leans more towards "development and implementation", while the user layer leans more towards "operation and configuration". The former has higher requirements for the technical capabilities of customers.

3-"Bottom layer"
    The bottom layer of a DSP chip is mainly the fundamental part that directly interacts with hardware and supports the operation of upper-layer functions. Its core contents include:
    ① Hardware Abstraction Layer (HAL) : Encapsulates the internal hardware details of the chip (such as registers, computing units, peripheral interfaces, etc.), provides a unified software call interface, and shields hardware differences.
    ② Driver program: The underlying code that controls the peripheral devices of the chip (such as ADC, DAC, timer, communication interface, etc.), responsible for hardware initialization, data reading and writing, and status management.
    ③ Basic operation library: The optimized low-level mathematical operation module (such as FFT, convolution, filtering, etc.) utilizes the special instruction set of DSP (such as multiplication and addition instructions) to achieve efficient basic signal processing operations.
    ④ System kernel: It includes basic functions such as task scheduling, interrupt management, and memory allocation, ensuring the real-time performance and multi-task operation of the chip (some DSPS are equipped with real-time operating system kernels).
    These contents are developed and maintained by chip manufacturers and serve as the foundation for the operation of the upper layer (protocol layer, application layer). Customers usually do not need to modify them and cannot do so.
    Attachment: EQ Adjustment of DSPS with Different Frequencies