MCU- Program Flash Bottleneck

[dknguyen]

There's something I've been looking at and I'm not quite sure about how it's overcome. I haven't been able to find much either. A lot of the MCU's now seem to run much faster than the program flash. Doesn't that largely make the fact that the processor can run at 100MHz irrelevant? Because from what I can tell these microcontrollers tend not to have a cache or SRAM shadowing or anything like that. THey might have pipelines but that still requires an instruction to be fetched per clock cycle.

Or is there something different now about the program Flash being used on the chip?

 

[Sceadwian]

Just because the processor runs at 100mhz doesn't mean it process 100 million instructions per second. It can take MANY clock cycles for specific instructions to execute well bellow the read rate of the flash memory. Depending on the processor while it may need a 100mhz clock it could only work at 25MIPS well within the range for simple flash memory. If you're using a chip that is that high speed that has to fetch instructions quickly it's simple, the flash is designed to be access that fast. There is no hard limit to flash memory access.