跨平台更新制作rootfs


在x64( pc /ubuntu 18.10 )跨平台编译arm64 的debian rootfs完整镜像,通常地,更新rootfs都是直接放在目标机上面,制作更新好rootfs后再拷贝回编译机。

对于目标机平台,通常拷贝rootfs需要非运行时环境,所以例如在emmc的rootfs需要通过sd卡系统启动去执行拷贝操作。

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zigbee security


[zigbee Specification Revision 22 1.0]() ->4.2.1.2.1 Security Keys 详细介绍了zigbee 密钥类型,包含用以两个设备应用层(apl)单播的link key和用以所有设备其它层(network、mac)、以及应用层广播的network key。

通常地,network key 通过设备加入网络后密钥传输流程获取,而link key 则通过密钥请求或者出厂预定义安装,类似bdb install code已经实现应用预配置tc link key,oob传输到tc。

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基于zstack 的zigbee3.0 第一个例程


Z-Stack 3.0 Sample Application User's Guide.pdf->1.2 Sample Projects 详细介绍了例程的功能,这里我们选择跑通SampleLight / SampleSwitch 描述的功能,中间可能涉及led和key的驱动移植,同时通过抓包详细了解其网络建立、设备加入网络以及数据交互,至此,对zigbee和z-stack有个感性认识。

Z-Stack 3.0 Sample Application User's Guide.pdf->3 Using the Sample Applications->3.2.1 SampleLight, SampleSwitch 详细介绍了该样例的功能。从描述来看,SampleLight 作为常供电设备扮演协调器角色,同时通过LED1用以指示灯开关,可以通过菜单导航,确认按键本地开关LED1,SampleSwitch因为是电池设备工作在终端设备模式,同时通过液晶的菜单导航能够远程开关 SampleLight的LED1。

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base device behavior


bdb 框图

bdb 是zigbee 应用层上面的纯接口层,提供了设备操作网络相关的交互行为,也就是bdb已经概况总结了可能的人机操作网络的行为(例如,建立网络/加入网络/离开网络),并且规划成接口,方便应用层直接调用,从而进一步规范厂商的应用行为,达到标准化。

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man bash redirection


Before a command is executed, its input and output may be redirected using a special notation interpreted by the shell. Redirection allows commands' file handles to be duplicated, opened, closed, made to refer to different files, and can change the files the command reads from and writes to. Redirection may also be used to modify file handles in the current shell execution environment. The following redirection operators may precede or appear anywhere within a simple command or may follow a command. Redirections are processed in the order they appear, from left to right.

Each redirection that may be preceded by a file descriptor number may instead be preceded by a word of the form{varname} . In this case, for each redirection operator except >&- and <&-, the shell will allocate a file descriptor greater than or equal to 10 and assign it to {varname}. If >&-or<&-is preceded by {varname}, the value of {varname} defines the file descriptor to close.

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