Adaptive Real-Time Memory Accelerator 即 自适应实时存储器加速器 ，主要功能是弥补高速cpu与相对低速flash指令读取之间的矛盾。当指令flash读取速度足够快，cpu就可以相应提速。目前stm32F42x系列，mcu主频提高到了190mhz。

    摘录stm官方文档：

3.2 Adaptive real-time memory accelerator (ART Accelerator)

The ART Accelerator is a memory accelerator which is optimized for STM32 industry-standard ARM  Cortex-M4 with FPU processors. It balances the inherent performance 

advantage of the ARM Cortex-M4 with FPU over Flash memory technologies, which 

normally requires the processor to wait for the Flash memory at higher frequencies.

To release the processor full 225 DMIPS performance at this frequency, the accelerator 

implements an instruction prefetch queue and branch cache, which increases program 

execution speed from the 128-bit Flash memory. Based on CoreMark benchmark, the 

performance achieved thanks to the ART Accelerator is equivalent to 0 wait state program 

execution from Flash memory at a CPU frequency up to 180 MHz.


    注意：1，cpu执行速度高于flash指令读取速度时，cpu会自动加入空转等待指令读取。

          2，cpu执行DMA时，也因该具有侦测地址数据总线的能力，当总线忙时，cpu等待总线空闲。此时，还有解决思路，即使用总线矩阵，多套总线访问内存。