Source: Tiger Says Chip
Original Author: Tiger Says Chip
This article introduces the concept, characteristics, and position of hardware processing modules in systems.
1. Basic Concept of Hardware Processing ModulesFocus on Specific Functions Hardware processing modules can be understood as a piece of logic circuit “customized” within a chip, designed to perform a specific type of fixed computation or operation. Unlike a CPU, which needs to read and parse various general-purpose instruction sets, it is inherently highly targeted for specific tasks. A vivid analogy: if the CPU is a versatile “Swiss Army knife” that can do everything but may not be the most efficient; the hardware processing module is like a “specialized power tool” that only does specific jobs but does them quickly and with low energy consumption.Independence from General Instruction Streams Unlike CPUs, hardware processing modules do not require complex instruction decoding and cache management mechanisms, allowing these resources to be used for data parallel processing, pipelining, or other specialized optimizations. The benefit is that they can complete more computations in a shorter time while also reducing power consumption and chip area usage.
2. Position of Hardware Processing Modules in Systems
Relationship with CPU, Bus, and Memory In a typical System on Chip (SoC), there are usually several main “roles”: CPU: executes general software tasks and provides flexible control and management capabilities. Memory: stores data and program instructions. Bus: connects the CPU, memory, and other functional modules, responsible for data transfer and control information exchange. Hardware processing module: focused on specific data processing or interface functions, such as image processing, encryption/decryption, network communication, etc. In this architecture, the CPU controls and reads the status of the hardware processing module’s registers (known as the “control plane”), while the hardware processing module interacts directly with the bus or memory to handle the actual data flow (known as the “data plane”).Implementation in Hardware Description Language (HDL) Hardware processing modules are often written in hardware description languages such as Verilog or VHDL, and after synthesis, layout, routing, and fabrication, they become independent logic units operating within the SoC. A vivid analogy: in a “smart factory”, the CPU is the management level, responsible for issuing commands; the hardware processing module is like a specialized production line, customarily completing the manufacturing or processing of a specific type of product.
3. Core Characteristics of Hardware Processing Modules
Configuration Status Register (CSR) Module Hardware processing modules typically include one or more configuration status registers for: Receiving control commands: Software can set the operating mode, operational parameters, etc., of the hardware processing module through these registers; Reporting operational status: The hardware processing module can write execution progress, fault information, etc., to these registers for the software to read and make corresponding adjustments.High Throughput Data Processing Hardware processing modules often face a large number of read and write operations on data, and they typically possess the following capabilities: High bandwidth interfaces: capable of processing and transmitting data faster than general CPUs; Parallel processing: able to handle multiple data points simultaneously (pipelined or parallel logic structures), enhancing efficiency.No Need for General Instruction Decoding Because they are oriented towards fixed algorithms or protocols, hardware processing modules do not need to load instructions from memory, decode, and execute like CPUs; instead, they directly perform built-in logical operations. A vivid analogy: the CPU first looks at the “manual” before doing the work; the hardware processing module has the “process” hardwired into the circuit, knowing what to do as soon as power is applied.
4. Typical Categories of Hardware Processing Modules
Based on the type and function of data operations, common hardware processing modules can be divided into the following three categories: Data Transfer Modules For example, DMA (Direct Memory Access). Its main responsibility is to transfer data from one storage area to another or from storage to other hardware modules. The significance lies in: allowing the CPU to avoid transferring data byte by byte, significantly reducing the CPU’s burden and improving system throughput.Data Processing Modules For example, encryption modules, compression/decompression modules, image filtering modules, etc. They implement specific algorithm logic in hardware, quickly processing input data and outputting results. Some data processing modules may also include small DMA to read data and write processing results back to memory, further reducing dependency on the CPU.Data I/O Modules For example, Ethernet modules, PCIe controllers, etc., used for high-speed interaction with the external world (networks, peripherals), often also include lower-level protocol processing functions (such as parsing and packaging network protocol frames). Through specialized hardware pipelining, they can efficiently complete send and receive operations at extremely high data rates.
5. Advantages of Hardware Processing Modules
Specialization Leads to High Efficiency The specialized design of custom circuits allows for fast task execution, low energy consumption, and often enables greater parallelism within a certain area. More Optimized Resource Usage Because they do not require general instruction sets and decoding logic, hardware processing modules can directly utilize valuable chip resources for data pathways. For the system, this also reduces unnecessary load on the CPU. More Friendly to Real-Time or Large Data Volume Requirements In scenarios where big data, high throughput, or real-time performance is critical, hardware processing modules often provide more stable and predictable performance. CPUs may experience greater performance fluctuations due to multitasking switches or cache jitter.
6. Considerations in Engineering Practice
Function Verification and Debugging The logical design of hardware processing modules requires extensive simulation and verification in the early stages. Once errors occur after fabrication, the cost of modification is extremely high, so various usage scenarios must be thoroughly tested during the design phase.Software Interface Design It is essential to define the register addresses, access methods, and interrupt mechanisms of the hardware processing module, allowing software to easily configure, control, and monitor status. If there are many peripherals, a unified register mapping plan is needed to avoid conflicts, and abstraction and encapsulation should be well done at the driver level.Compatibility and Expansion Consideration must be given to the potential addition of new algorithms or functions in the future, especially in rapidly evolving market demand scenarios, which can be enhanced through reconfigurable logic (such as FPGA) or reserved hardware interfaces. For chips after mass production, upgrading is challenging, so it is essential to leave room during design to accommodate potential technological or market changes.
7. Conclusion
Hardware processing modules play the role of “specialized operators” in SoCs: they focus on specific data processing tasks, eliminating the overhead of general instruction streams while significantly improving processing efficiency. They are typically integrated in a modular fashion on the chip and work in conjunction with the CPU, memory, and bus. The CPU issues commands and obtains status information through configuration registers, while the hardware processing module efficiently handles most data transfer and core computations. From DMA, encryption engines to network interfaces, these hardware processing modules endow SoCs with powerful parallel processing capabilities and high bandwidth data throughput, which are crucial for modern electronic systems. If we compare an SoC chip to a city, the CPU is like the city government responsible for macro scheduling and management, while various hardware processing modules are like specialized institutions in the city (fire departments, hospitals, delivery centers, etc.), each with its unique responsibilities and highly specialized. It is precisely because of these specialized “departments” that the entire city can operate efficiently and reliably in an environment of high concurrency and high-speed data flow.ENDReprinted content only represents the author’s viewsdoes not represent the position of the Institute of Semiconductors, Chinese Academy of SciencesEditor: XiaoshuaiResponsible Editor: MuxinSubmission Email: [email protected]Previous Recommendations1. The Institute of Semiconductors has made progress in the research of bionic coverage-type neuron models and learning methods2. The Institute of Semiconductors has made significant progress in inverted structure perovskite solar cells3. Why is copper used as interconnect metal in chips?4. What exactly is 7nm in chips5. Silicon-based integrated optical quantum chip technology6. How anomalous is the quantum anomalous Hall effect? It may lead to the next revolution in information technology!