設(shè)計(jì)師面對(duì)復(fù)雜的選擇為MCUs和微處理器之間的界限模糊

　　看看微控制器（MCU）的高端部分，你會(huì)發(fā)現(xiàn)具有微架構(gòu)和指令集特性的集成電路類似于微處理器中的芯片。事實(shí)上，企業(yè)如德克薩斯儀器（TI）和飛思卡爾提供單片機(jī)和嵌入式微處理器與一個(gè)共享的遺產(chǎn)有針對(duì)性。不過(guò)，這兩個(gè)部分之間的差異很大，從公司的芯片設(shè)計(jì)和制造策略到集成的功能集以及硬件中根深蒂固的軟件支持。嵌入式設(shè)計(jì)團(tuán)隊(duì)在考慮設(shè)備選擇之前，必須仔細(xì)考慮其應(yīng)用，以便在選擇MCU或微處理器路徑時(shí)做出正確的選擇。

　　從高層次上看微控制器和微處理器技術(shù)，它們似乎相互交叉。在兩個(gè)陣營(yíng)中都有兼容的或重疊的指令集，MCU時(shí)鐘頻率已經(jīng)升級(jí)到接近微處理器端部的一個(gè)點(diǎn)。

　　Scalable families

　　Let us consider some examples of what appears to be a smooth progression of compatible processor technology moving up an MCU product line and into the microprocessor area. Freescale offers the Kinetis MCU family based on the ARM Cortex-M4 core， including products such as the K10， K20， K30， K40， and K60 MCUs. On the microprocessor side， Freescale offers the i.MX microprocessor family. The i.MX1/2， i.MXL， and i.MXS families are based on an ARM9 core. The i.MX3x family is based on an ARM11 core， and the i.MX5x family is based on an ARM Cortex-A8 core.

　　Clearly there are differences in the CPU cores used across the Freescale ARM-based portfolio. We will discuss architectural differences in cores throughout the article， but in a simplified comparison， they all support the same basic instruction set. The Cortex-M4 core is optimized for low power and a smaller die size. The ARM9， ARM11， and ARM Cortex-A8 progression basically represents a scaling of performance capabilities. We could make largely the same type of comparison with Freescale‘s PowerPC-based portfolio including the MPC6x and MPC7xmicroprocessor families and the PowerPC MCU family.