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Relationship between ICache and ART of STM32F7

Question asked by koumoto.yasuhiko on Oct 7, 2015
Latest reply on Oct 10, 2015 by koumoto.yasuhiko
Hello experts,
I am working with STM32F7 Discovery board and STM32CubeF7.
I made a small benchmark test and had found a stange phenomenon.
It is about the relationship between ICache and ART Accelerator.
Regarding instruction fetch form the flash, there are tow paths.
One is the path which Flash-ART-ITCM-CPU.
Another is the path which Flash-AXIM-CPU.
When accessing ITCM area (i.e. address is 0x002xxxxx), I tried the following three options.
1) ICache is enable and ITCM is enable.
2) ICache is enable and ITCM is disable.
3) ICache is disable and ITCM is disable.
The results were,
1) and 2) are almost the same execution time but 3) is twice later than 1) and 2).
The execution time of 3) is almost the same as the case of fetching from AXIM area (i.e. address is 0x080xxxxx) on conditon ICache is disable.
The results seems that ART Accelerator was not working.
I guess ART would not work when ICache was disable.
Is it true?
Can anyone explain the reason?
Thank you in advance and best regards,
Yasuhiko Koumoto.