嵌入式系统学习笔记.docx

嵌入式系统学习笔记.docx

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嵌入式系统学习笔记

入门难，视频教程+看书

嵌入式基础知识

嵌入式系统，以应用为中心，以计算机技术为基础，且软硬件可裁剪，的专用计算机系统。

带有微处理器的专用系统（单片机系统、带OS的ARM系统）。

这些对比不是绝对的

交叉编译？

嵌入式系统特点：

系统内核小、专用性强、系统精简、实时性、专用开发软件和环境。

嵌入式处理器，核心，

外围设备：

存储器：

xramxflash

接口：

并口，RS232串口，以太网接口

入机接口：

LCD，触摸屏

嵌入式软件层：

应用层，驱动层，OS层

嵌入式开发类：

硬件开发（电路、驱动）、系统开发（linux、wince）、软件开发（应用程序、GUI）

嵌入式学习方法

Linux常用命令_格式

#command[-options]parameter1parameter2......

VI

H左，L右，J下，K上

V可视，

Dw删除单词的后半部分，D￥删除同行光标后的内容。

2DD删除两行。

U撤销，ctrl+r反撤销

P粘贴

R修改当前字符

Cw替换后插入字符

C$删除行后插入

2cc删除2行后插入

GCC编译器

Gcc-omainmain.c

Gcc输出可执行文件名程序

GNUmakefile

制定编译规则，完成整个软件项目处理；分开存储，个别处理；

Shell命令解释器，编程环境

Win下的批处理

变量+规则

建立交叉编译环境

交叉编译：

在一个平台（体系结构x86、ARM、操作系统win、linux）上生成另一个平台上的可执行代码。

体系结构相互配合操作系统

Gcc编译四个阶段：

1　预处理，不生成文件【预处理器cpp】

2　转换为汇编语言，生成.s的文件【编译器egcs】

3　转变为目标代码（机器代码）生成.o文件【编译器as】

4　连接目标代码和库文件，生成可执行程序【链接器ld】

Linux平台工具

Arm920t-eabi、

Eabi优化浮点数运算

Windows平台工具

secureCRT（中断仿真程序，类似于超级终端）

Notepad++

ADS集成开发环境（操作类似于keil、中文路径下的工程文件不能被打开）

CodeWarriorIDE

HJTAG（ARM仿真、调试代理）

Dnw

ARM微处理器

Arm7采用风诺依曼结构

Arm9采用哈佛结构

命名规则

MMU，虚拟内存单元

MPU，内存保护单元

ARM体系结构

ARM数据类型

ARM存储格式

ARM处理器工作模式

ARM中断

S3c2440a芯片

PLL倍频作用

写1清零

S3C2440存储器控制器

<>:

表示以标准形式调用

慎用静态链接

Makefile

规则：

产生结果的格式

Targets：

prerequisites

Command

目标依赖

命令

Main.o：

main.c

Gcc-cmain.c

伪目标（phonytargets）

变量：

Hello：

main.ofun.o

Gccmain.ofun.o

添加fun2.c

文件编程

Linux中文件编程：

linux系统调用、c库

linux系统调用：

intcreat（constchar*filename，mode_tmode）

常见创建模式：

可执行->1

可写->2

可读->4

File_creat.c

Intcreat（constchar*pathname,intflags,mode_tmode）

Mode指定文件权限

File_open.c

Intopen（constchar*pathname,intflags,mode_tmode）

例如fd=open（argv[1],O_CREAT|O_RDWR,0755）

注意o_creat：

表示该文件不存在，系统会自动创建

库函数创建，文件参数由第三个参数决定；第三个参数可以没有

B区分二进制、文本文件

File_read.c

Intread（intfd,constvoid*buf,size_tlength）

File_write.c

Intwrite（intfd,constvoid*buf,size_tlength）

File_lseek.c

Intlseek（intfd,offset_toffset,intwhence）

将文件读写指针相对whence移动offset个字节

Whence可以用：

SEEK_SET（相对文件开头）、SEEK_CUR

Lseek计算文件长度：

lseek（fd,0,SEEK_END）

文件属性判断：

Access：

intaccess（comsthar*pathname,intmode）

//mode是要判断的访问权限（R_OK/W_OK/X_OK/F_OK（文件存在）），测试成功函数返回0，否则返回-1.

（英文版）

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