A brief explanation of using external RAM in STM32 MDK-EEWORLD

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Introduction:

Development Board Shenzhou King STM32F207 Development Board

Problem Description:

When using emwin, due to the large number of variables occupied, the embarrassing situation of insufficient internal RAM of STM32F207 appeared. The development board comes with 4M external SRAM. Therefore, considering the balance between speed and storage, the internal RAM of the chip is used as the stack area, and the external RAM is used to store other variables.

Modifications:

The startup file is startup_stm32f2xx.s file

1. Add the flag: DATA_IN_ExtSRAM EQU 1; mainly to facilitate the control of switching between internal and external RAM

2. Modify the stack area: IF DATA_IN_ExtSRAM == 1

__initial_sp EQU 0x20000000 + Stack_Size

ELSE

__initial_sp

ENDIF

3. Initialize external RAM before entering the main function

There are two ways to initialize

The first one: initialize in SystemInit

The SystemInit function is located in the system_stm32f2xx.c file

Define macro variable DATA_IN_ExtSRAM

In this way, the function SystemInit_ExtMemCtl will be called when the system is initialized

Modify the SystemInit_ExtMemCtl function content to initialize FSMC RAM

The second

Call the RAM initialization function before calling the main function in startup_stm32f2xx.s to complete the RAM initialization

IMPORT __main

IMPORT SystemInit

IMPORT SRAM_Init

LDR R0, =SystemInit

BLX R0

LDR R0, =SRAM_Init

BLX R0

LDR R0, =__main

ENDP

Of course, the most painful way is to initialize the external RAM in startup_stm32f2xx.s, but it needs to be modified into assembly language

Finally, modify the MDK configuration and check the external RAM in option->target

A brief explanation of using external RAM in STM32 MDK - Hanjiang Duchui - Hanjiang Duchui

Then you can try to define a large array.

Keywords：STM32 MDK Reference address：A brief explanation of using external RAM in STM32 MDK

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