基于XIP FLASH的嵌入式软件设计与应用

Design and application of embedded software based on XIP FLASH

传统NOR FLASH并行地址和数据总线的引脚过多,使电路设计的复杂性增大,同时也会增加电路板布线空间。为了解决这一弊端,部分微控制器支持SPI eXecute in Place(XIP)接口,SPI NOR-FLASH应运而生。基于此,文中提出一种嵌入式软件设计方案。该方案充分发挥XIP FLASH片上执行代码的关键属性,利用GNU编译器的工作原理,通过链接器的链接脚本将嵌入式软件程序存储在XIP FLASH中,运行时代码段和只读数据段存放在XIP FLASH中,只需将数据段及操作XIP FLASH的关键代码搬运至RAM中运行。此外,对嵌入式软件的执行流程进行设计与说明。所提方案简单、易操作,已在单相和三相表载波通信单元、Ⅰ型采集器通信单元、Ⅱ型采集器、集中器载波通信单元得到充分验证,可广泛应用于用电信息采集系统、输配电系统的本地通信等领域。

The parallel address and data bus of the traditional NOR FLASH have too many pins,which increases the complexity of circuit design and also increases the wiring space of circuit board. To solve this problem,some microcontrollers can support SPI eXecute in Place(XIP) interface,SPI NOR-FLASH is born at the right moment. On this basis,a design scheme of embedded software is proposed. In this scheme,the key attributes of the code executed on the XIP FLASH chip is fully utilized. By means of the working principle of the GNU compiler,the embedded software program is stored in XIP FLASH by means of the link script of the linker,and the code segment and read-only data segment are stored in XIP FLASH for execution in the runtime. Only the data segment and the key code to operate XIP FLASH need to be moved to RAM for operation. The execution process of the embedded software is designed and explained. The proposed scheme is simple and easy to operate,and has been fully verified in single-phase and three-phase meter carrier communication unit,type Ⅰ collector communication unit,type Ⅱ collector and concentrator carrier communication unit,which prove that it can be widely used in power utilization information acquisition system,local communication of power transmission and distribution system and other fields.