設(shè)計師面對復(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。事實上，企業(yè)如德克薩斯儀器（TI）和飛思卡爾提供單片機和嵌入式微處理器與一個共享的遺產(chǎn)有針對性。不過，這兩個部分之間的差異很大，從公司的芯片設(shè)計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)計團隊在考慮設(shè)備選擇之前，必須仔細考慮其應(yīng)用，以便在選擇MCU或微處理器路徑時做出正確的選擇。

　　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。在兩個陣營中都有兼容的或重疊的指令集，MCU時鐘頻率已經(jīng)升級到接近微處理器端部的一個點。

　　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.