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Performance of Running Code in External RAM

xinghua
Associate
Posted on August 04, 2009 at 10:15

Performance of Running Code in External RAM

2 REPLIES 2
xinghua
Associate
Posted on May 17, 2011 at 12:54

We are using High Density Series STM32 chip. The embedded SRAM is up to 64KB. We try running code from external SRAM, and it seems extremely ''slow''.

I am wondering how the performance will be like if running linux, considering normally linux kernel is large (over several hundred KBytes) and copied from a stroage device(flash) to RAM, and then wholly running in RAM.

ivanov-i
Associate II
Posted on May 17, 2011 at 12:54

The external memory is not a good place for running a code for STM32. As AN2784 states the minimum access latency for the external memory is 3 cycles for half a word even if you put no delays in the configuration register (Figure 6).

In addition, the external memory is connected to D-bus, which means that there will be more delays waiting for data transfers over the same bus.