first, the embedded system composition:
Embedded system = Embedded hardware system + Embedded software system, embedded hardware system = Embedded Processor (CPU) + Embedded Peripheral device (ROM + RAM + I/O device + ...) ）；
Embedded software system = Embedded operating system + embedded application;
second, embedded hardware system structure diagram:
embedded microprocessor:
(1) Embedded processor = {Processor Core, three large bus (data, address, control), auxiliary circuit (clock, reset circuit ...), on-chip I/O};(2) embedded processor is divided into three kinds: embedded microprocessor/Embedded microcontroller/embedded DSP; a)embedded microprocessor: CPU (relative to the CPU of general computer microprocessor), small size, low power consumption; b) Embedded microcontroller: Single chip microcomputer, the CPU, memory and other peripherals packaged together;
c) Embedded DSP: processing discrete time signals, compiling efficiency and high execution speed;
What are the similarities between embedded microprocessors and general purpose microprocessors? What's the difference? Similarities: (1) external interface: All kinds of bus and auxiliary circuit interface, (2) processing function: similar instruction function classification; the difference: (1) The number of instructions in the instruction system; (2) instructions Form: The embedded microprocessor uses the thin instruction set (RISC), the general microprocessor uses the complex instruction set (CISC), (3) The processor structure design: The embedded system uses the pipeline structure design; (4) Processor technology and application indicators: Due to the different working environment;
Peripheral Equipment:
refers to the embedded system to complete the storage, communication, debugging, display and other ancillary functions of the other components;
Peripheral devices = storage devices (RAM + SRAM + Flash + ...) + Communication equipment (RS-232 interface + SPI interface + Ethernet interface + ...) ) + display device (display) + ... ；
(1) storage device:
memory = RAM (random access memory) + ROM (read-only memory);
RAM Access data is fast, data loss after power-down; ROM speed is slow, the data will not be lost after power-down;
a) RAM = SRAM (static memory) + DRAM (dynamic memory); SRAM is the use of bistable trigger to save information, as long as not power down, the data will not be lost;
DRAM cost, integration, power consumption is significantly better than SRAM;
b) rom = Flash (non-slipped storage technology) + ROM;
Flash = NOR flash + NAND flash; NOR Flash: In-chip execution, so that the application can run directly in Flash, no longer have to read the code into the system RAM;
NAND Flash: Extremely high cell density for high storage density
From for notes (Wiz)
ARM Learning notes an introductory article
