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Linker file STM32F429

Question asked by vugs.michel on May 21, 2014
Latest reply on May 21, 2014 by vugs.michel

We have made a custom board which uses a STM32F429II. On that board we also have a SDRAM memory chip of 512Kbit that is connected to the STM32 with the FMC peripheral.

We confirmed that the memory chip is working correctly as we can write and read to the chip using functions like:

uint32_t SDRAM_Read32b(uint32_t adr)
  uint32_t ret_wert=0;

  ret_wert = *(__IO uint32_t*)(SDRAM_START_ADR + adr);


Which uses pointers to point to the SDRAM adress. 

In previous projects with stm32 wich used SRAM we could create a variable with a certain attribute:

__attribute__((section(".sram_data"))) char buffer[10000];

and then use this variable as if it is normal RAM memory.

This requires to change the linker script which the compiler uses. But when we do the same with the new STM32F429 chip the data is not stored at all.

We are also not sure how to correctly adapt the linker script. Is there someone who also used this for embedded SDRAM or who can give us a correct example of a linker script adapted for external RAM?