多核微控制器提供新的嵌入式期權

　　嵌入式系統設計者面臨著不斷增長的性能需求和更快的市場需求。嵌入式處理器需要執行擴展的任務集，通常是實時的。同時，應用要求高吞吐量和節能，加上外形小、成本低。多核微控制器單元（MCU）提供了一個可行的新的解決方案，利用模塊化設計，以經濟的價格提供多種性能的提高。

　　幾十年來，隨著集成電路晶體管數量的增加，芯片性能保持同步。越來越先進的架構，包括緩存和流水線技術，使芯片設計者能夠利用不斷增長的硅密度來不斷提高處理速度。那不再是事實了。芯片設計者已經用盡了替代體系結構的可能性。生產力的跳躍已經從穆爾定律的速度下降到不到一半。提高生產率的唯一方法是通過使用多個CPU來提高模塊化率。這導致了多核微控制器的發展。

　　Hardware： homogeneous versus heterogeneous

　　We define a multicore MCU as a microprocessor featuring two or more CPUs that coherently share a common memory. In the multicore architecture， each processor features its own instruction stream acting on its own data stream （MIMD）。

　　Multicore MCUs can be classed as homogeneous or heterogeneous. As the name suggests， homogeneous modules feature two identical CPUs that can run operations in parallel or redundantly. Designed for safety applications， the Hercules line fromTexas Instruments boasts dual ARM Cortex-R4F CPUs running in lockstep. They perform the same operation， then compare the results each clock cycle， effectively establishing a “safe island” that provides designers with a reliable foundation to implement more sophisticated operations in medical， industrial， and automotive applications. To remove potential common failure modes， the design team oriented the chipset 90° to one another and introduced a delay in the timing of the processors. The chip can operate at up to 200 MHz and sports 32 Mbytes of flash memory.