Linux device drivers (iii)

Hardware Foundation for Drive design

processors are categorized as:

1. General purpose Processors (GPP) do not optimize architecture and instruction sets for specific application areas, they have generalized general-purpose architectures and instruction sets to support complex operations and to easily add newly developed features. In general, a generic processor core is included in the embedded microcontroller (MCU) and microprocessor (MPU).

MPU typically represents a CPU (central processing unit), while the MCP emphasizes the integration of the CPU, memory and peripheral circuitry into one chip. is a typical MCU internal structure

2, Digital signal Processor (DSP) for communication, image, voice and video processing and other fields of the algorithm two design. It contains a separate hardware multiplier. The multiplication instruction of DSP is usually completed in a single cycle, and the large number of repeated multiplication in algorithms such as convolution, digital filtering, FFT (Fast Fourier transform), correlation and matrix operation are optimized.

DSP is divided into two categories: one is fixed-point DSP, and the other is floating-point DSP. Floating-point DSP floating point arithmetic is implemented by hardware, which can be completed in single cycle, so its floating-point arithmetic processing speed is higher than that of fixed-point DSP. Fixed-point DSP can only simulate floating-point arithmetic with fixed-point arithmetic.

3, specialized processor (ASP) and ASIC (special integrated circuit)

4, the central processing system architecture can be divided into two categories: a class of von Neumann structure, a class of Harvard structure

The von Neumann structure is also a Princeton structure, a storage structure that merges program instruction memory and data memory together. The program instruction store address and data storage address point to different physical locations of the same memory, so the program instruction and data are the same width. And the Harvard structure stores the program bus and the data bus separately, and the instruction can have different data widths. In addition, the Harvard structure uses the independent program bus and the data bus, respectively, as the special communication path between the CPU and each memory, and has high execution efficiency.

Describes the differences between the von Neumann structure and the Harvard structure:

5, from the instruction set point of view, the central processing unit can also be divided into two categories, namely RISC (compact instruction set) and CISC (complex instruction set). CSIC emphasizes the ability to enhance the instruction, reduce the number of target code, but the instruction is complex, the instruction period is long, while CSIC emphasizes minimizing instruction set, instruction single cycle execution, but the target code is larger.

Classification of Memory: as described:

Memory is mainly classified as read-only memory (ROM), Flash (Flash), Random access memory (RAM), optical, magnetic media storage.

Rom can also be subdivided into non-programmable ROM, programmable rom (PROM), erasable programmable ROM (EPROM), and electrically erasable programmable ROM (EEPROM), EEPROM can be completely software to erase.

Serial and bus:

The RS-232 modified version of RS-232, released in 1969, is the most widely used serial interface for embedded systems and is designed to connect DTE (data Terminal equipment) with DCE (data communication devices). The RS-232 standard interface has 25 interfaces (4 data lines, 11 control lines, 3 timing lines, 7 spare and undefined lines), only 9 are commonly used, they are rts/cts (request send/clear Send flow control), RXD/TXD (data transmit/receive), DSR/DTR (Data Terminal ready/ Data set Ready flow control), DCD (Data carrier detection, also known as RLSD, i.e. receive line signal detection), ringing-ri (ringing indication), SG (signal ground) signal.

IIC (integrated circuit) bus: The two signals that make up the IIC bus are the data line SDA and the clock SCL.

USB (Universal serial bus), it has the advantages of high data transfer rate, easy expansion, plug-and-play and hot-pluggable.

Linux device drivers (iii)