Hi John
> Is there a simple guide that illustrates why this is so? I'd be interested to know why R/W variables shouldn't be put in ITCM or why code shouldn't be put in DTCM.
The best performance is achieved by placing the instruction in ITCM and the data in DTCM.
Cortex-M7 is equipped with a superscalar. Because of this, Cortex-M7 partially processes instructions simultaneously. Therefore, ITCM and DTCM have different I / F bit widths and numbers.
The connection between ITCM, DTCM and CPU (TCU) is as follows:(The access bit width of ITCM is 64 bit * 1, and the access bit width of DTCM is 32 bit * 2.)
If you want to know more info, Please confirm "Arm Cortex-M7 Processor Technical Reference Manual 5.8. TCM interfaces.(http://infocenter.arm.com/help/index.jsp?lang=en)
RM describes that
The Prefetch Unit (PFU) can fetch instructions from any of the TCM interfaces. The Load Store Unit (LSU) and the AHBS interface can each read and write data using any of the TCM interfaces. Best performance is achieved if code is placed in ITCM and data in DTCM. However, there is no functional restriction in which TCM, code and data is placed.
Best Regards,
T.Kashiwagi
Hi John
> Is there a simple guide that illustrates why this is so? I'd be interested to know why R/W variables shouldn't be put in ITCM or why code shouldn't be put in DTCM.
The best performance is achieved by placing the instruction in ITCM and the data in DTCM.
Cortex-M7 is equipped with a superscalar. Because of this, Cortex-M7 partially processes instructions simultaneously. Therefore, ITCM and DTCM have different I / F bit widths and numbers.
The connection between ITCM, DTCM and CPU (TCU) is as follows:(The access bit width of ITCM is 64 bit * 1, and the access bit width of DTCM is 32 bit * 2.)
If you want to know more info, Please confirm "Arm Cortex-M7 Processor Technical Reference Manual 5.8. TCM interfaces.(http://infocenter.arm.com/help/index.jsp?lang=en)
RM describes that
The Prefetch Unit (PFU) can fetch instructions from any of the TCM interfaces. The Load Store Unit (LSU) and the AHBS interface can each read and write data using any of the TCM interfaces. Best performance is achieved if code is placed in ITCM and data in DTCM. However, there is no functional restriction in which TCM, code and data is placed.
Best Regards,
T.Kashiwagi
