ABB UFC760BE142 3BHE004573R0142 脉冲输入（PI）模块

ABB UFC760BE142 3BHE004573R0142  脉冲输入（PI）模块

嵌入式系统包含:硬件层、中间层、系统软件层和应用软件层(1) 硬件层: 嵌入式微处理器、存储器、通用设备接口和I/O接口。嵌入式核心模块 = 微处理器 + 电源电路 + 时钟电路 + 存储器Cache:位于主存和嵌入式微外理器内核之间，存放的是近一段时间微外理器使用多的程序代码和数据。它的主要目标是减小存储器给微处理器内核造成的存储器访问瓶颈，使处理速度。(2) 中间层 (也称为硬件抽象层HAL或者板级支持包BSP)它将系统上层软件和底层硬件分离开来，使系统上层软件开发人员无需关系底层硬件的具体情况，根据BSP层提供的接口开发即可。

BSP有两个特点: 硬件相关性和操作系统相关性。设计一个完整的BSP需要完成两部分工作:嵌入式系统的硬件初始化和BSP功能.片级初始化:纯硬件的初始化过程，把嵌入式微处理器从上电的默认状态逐步设置成系统所要求的工作状态。板级初始化:包合软硬件两部分在内的初始化过程，为随后的系统初始化和应用程序建立硬件和软件的运行环境。

系统级初始化: 以软件为主的初始化过程，进行操作系统的初始化。

ABB UFC760BE142 3BHE004573R0142  脉冲输入（PI）模块

Embedded system includes: hardware layer, middle layer, system software layer and application software layer (1) Hardware layer: embedded microprocessor, memory, general device interface and I/O interface. Embedded core module = microprocessor+power supply circuit+clock circuit+memory Cache: located between the main memory and the embedded micro processor core, it stores the program codes and data that have been used by the micro processor in recent years. Its main goal is to reduce the memory access bottleneck caused by memory to the microprocessor core and speed up the processing. (2) The middle layer (also called the hardware abstraction layer HAL or the board-level support package BSP) separates the upper software and the lower hardware of the system, so that the upper software developer of the system can develop according to the interface provided by the BSP layer without being concerned with the specific situation of the lower hardware.

BSP has two characteristics: hardware dependency and operating system dependency. Designing a complete BSP requires two parts: hardware initialization of embedded system and BSP function. Chip-level initialization: pure hardware initialization process, which gradually sets the embedded microprocessor from the default state of power-on to the working state required by the system. Board-level initialization: the initialization process including hardware and software, which establishes the running environment of hardware and software for subsequent system initialization and application programs.

System-level initialization: a software-based initialization process that initializes the operating system.