IAP（In Application Programming）即在应用编程，IAP是用户自己的程序在运行过程中对User Flash的部分区域进行烧写，目的是为了在产品发布后可以方便地通过预留的通信口对产品中的固件程序进行更新升级。 通常实现IAP功能时，即用户程序运行中作自身的更新操作，需要在设计固件程序时编写两个项目代码，第一个项目程序不执行正常的功能操作，而只是通过某种通信方式(如USB、USART)接收程序或数据，执行对第二部分代码的更新；第二个项目代码才是真正的功能代码。(IAP (In Application Programming) is used in programming, IAP is the user's own program is part of the User Flash in the operation process of writing, the purpose is to after the release can be conveniently through the reserved communication port in the product firmware update. Usually the realization of IAP function, namely the user program running in the update operation, the need to write two project code in the design of firmware program, the first program does not perform the normal operation of the function, but only through some kind of communication (such as USB, USART) receiving programs or data on the implementation of the second part of the code update second; project code is the function of the real code.)