設計師面對復雜的選擇為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，你會發現具有微架構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。嵌入式設計團隊在考慮設備選擇之前，必須仔細考慮其應用，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，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.