Using external RAM with stm32f10xxg

[leventeyigel52]

Posted on February 14, 2013 at 13:28

I would like you use an external SRAM (is62wv2568bll) employing FMSC module in STM32F103xG. In example projects referred in AN2784 entitled ''Using the high-density STM32F10xxx FSMC peripheral to drive external memories'', there are some write/read examples. However, this examples aims to write/read blocks of data to/from external memory. What I want to do is to use this external memory like the internal RAM of the MCU. When I define a variable, this variable should be located to approriate place if the internal memory of the MCU is full. I think I need to configure both FSMC and IDE (IAR). Any help/suggestion is greatly appreciated.  

[Tesla DeLorean]

Posted on February 14, 2013 at 14:35

Normally you'd describe your memory map in a scatter file, or linker script like the .ICF files in IAR

The external memory is significantly slower, so you want to use it for less critical structures and variables.

You should be able to define a section/segment describing the external memory, and then associate data/code with being placed in that area.

[leventeyigel52]

Posted on February 14, 2013 at 16:20

Thanks for your quick reply clive. I understood that i can define external sram in icf file like below am i right?

define symbol _ICFEDIT_region_ROM_start_ = 0x08000000 ;

define symbol _ICFEDIT_region_ROM_end_ = 0x0807FFFF;

define symbol _ICFEDIT_region_RAM_start_ = 0x20000000;

define symbol _ICFEDIT_region_RAM_end_ = 0x20018000;

define symbol _ICFEDIT_region_RAM2_start_ = 0x60000000;

define symbol _ICFEDIT_region_RAM2_end_ = 0x63FFFFFF;

Can i use external ram without initialize FSMC? İf i can not how can i define variables at the beginning?