Peter Drescher

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7 years, 5 months ago.

External SRAM

Is mbed using the external SRAM for the stack ? I have ported the ebi test program from the CMSIS code and get some side effects. The ebi bank 0 seems to be initialized by the mbed code. The test is working, but some function calls to printf are scrambled.

Question relating to:

Last updated: 28 Jun 2021
The NuMaker Platform is an Internet of Things (IoT) application focused platform specially developed by Nuvoton. It supports ARM mbed OS 5.0 as well as Arduino interface, and is ideal …

2 Answers

cc li
7 years, 5 months ago.

Hi, NuMaker-PFM-NUC472 is equipped with 1MB external SRAM (0x60000000-0x600FFFFF). On mbed, it has arranged for some global/static variables/buffers and heap, and cannot be directly used for test program. The correct use of it is through heap allocation/deallocation (malloc/free in C and new/delete in C++) calls.

Accepted Answer
Sam Grove
7 years, 5 months ago.

Looks like the external SRAM is for the heap and internal SRAM for stack and other data but there are a few object files that place data on the external SRAM too

https://github.com/ARMmbed/mbed-os/blob/master/targets/TARGET_NUVOTON/TARGET_NUC472/device/TOOLCHAIN_ARM_STD/NUC472.sct#L13

Yes, besides for heap, the external SRAM is also used for some global variables/buffers. It is because 64KB internal SRAM is insufficient for e.g. network application.

posted by cc li 21 Nov 2016