I am using SDRAM for global data placement in my program. It is necessary to use SDRAM for my application. I have implemented powermode switch driver based on the SDK example, and all works well. The SDRAM is initialized through default dcd.c by defining "XIP_BOOT_HEADER_DCD_ENABLE" and "SKIP_SYSCLK_INIT" in the preprocessor. Similarly, SDRAM works well on its own.
When entering low power mode, the code hardfaults with an instruction bus error. I understand that this is because in low power mode the system PLL, which the SDRAM uses as it's clock source, is disabled. I am wondering if there is a way to switch the SDRAM clock source to the external oscillator so it can remain active in low power mode. Reading through other forum posts, it sounds like it is a very bad idea to mess with the SEMC clock source.
So I'm wondering what the best way to handle this is. I must use the SDRAM, since we are using files that take up too much memory to be placed in the on-chip RAM, but I'm not sure how to ensure SDRAM stays active during low power mode without modifying its clock.
I read about enabling self-refresh mode for the SDRAM before entering low power mode, and I tried to implement this in my project, but I don't think that the SDRAM is accessible in low power modes with this method, it just ensures that the data within the SDRAM isn't lost. So I don't think that this can be a solution.
What would be the best way to use SDRAM in low power mode and with the power mode switch driver?
