stm32 外部SRAM的初始化及使用

初始化和使用都比较简单

void FSMC_SRAM_Init(void)
{
  FSMC_NORSRAMInitTypeDef  FSMC_NORSRAMInitStructure;
  FSMC_NORSRAMTimingInitTypeDef  p;
  GPIO_InitTypeDef GPIO_InitStructure;
    
  RCC_AHBPeriphClockCmd(RCC_AHBPeriph_FSMC, ENABLE);
    
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOD | RCC_APB2Periph_GPIOG | RCC_APB2Periph_GPIOE |
                         RCC_APB2Periph_GPIOF, ENABLE);
  
/*-- GPIO Configuration ------------------------------------------------------*/
  /* SRAM Data lines configuration */
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1 | GPIO_Pin_8 | GPIO_Pin_9 |
                                GPIO_Pin_10 | GPIO_Pin_14 | GPIO_Pin_15;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_Init(GPIOD, &GPIO_InitStructure); 
  
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7 | GPIO_Pin_8 | GPIO_Pin_9 | GPIO_Pin_10 |
                                GPIO_Pin_11 | GPIO_Pin_12 | GPIO_Pin_13 | GPIO_Pin_14 | 
                                GPIO_Pin_15;
  GPIO_Init(GPIOE, &GPIO_InitStructure);
  
  /* SRAM Address lines configuration */
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1 | GPIO_Pin_2 | GPIO_Pin_3 | 
                                GPIO_Pin_4 | GPIO_Pin_5 | GPIO_Pin_12 | GPIO_Pin_13 | 
                                GPIO_Pin_14 | GPIO_Pin_15;
  GPIO_Init(GPIOF, &GPIO_InitStructure);
  
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1 | GPIO_Pin_2 | GPIO_Pin_3 | 
                                GPIO_Pin_4 | GPIO_Pin_5;                               
  GPIO_Init(GPIOG, &GPIO_InitStructure);
  
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11 | GPIO_Pin_12 | GPIO_Pin_13; 
  GPIO_Init(GPIOD, &GPIO_InitStructure);
   
  /* NOE and NWE configuration */  
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4 |GPIO_Pin_5;
  GPIO_Init(GPIOD, &GPIO_InitStructure);
  
  /* NE3 configuration */
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10; 
  GPIO_Init(GPIOG, &GPIO_InitStructure);
  
  /* NBL0, NBL1 configuration */
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1; 
  GPIO_Init(GPIOE, &GPIO_InitStructure);
  
/*
 * PG9 接到了 NORFLASH 的 CE 端，为了不让 NORFLASH的信号 影响到 SRAM
 * 这里先让 CE = 1 ,即 PG9 = 1 ,不然 SRAM 会测试不成功.
 * 或者在硬件设计时，NORFLASH 的 CE 管脚 上拉下.
 */
  //GPIO_InitTypeDef GPIO_InitStructure; 
  //GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
  //GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
  //GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  //GPIO_Init(GPIOG, &GPIO_InitStructure);
  //GPIO_SetBits(GPIOG,GPIO_Pin_9);
  //片选已上拉

/*-- FSMC Configuration ------------------------------------------------------*/
  #if 1
  p.FSMC_AddressSetupTime = 0;
  p.FSMC_AddressHoldTime = 0;
  p.FSMC_DataSetupTime = 2; 
  p.FSMC_BusTurnAroundDuration = 0;
  p.FSMC_CLKDivision = 0; 
  p.FSMC_DataLatency = 0;
  #elif 0
  p.FSMC_AddressSetupTime = 15;
  p.FSMC_AddressHoldTime = 15;
  p.FSMC_DataSetupTime = 15; 
  p.FSMC_BusTurnAroundDuration = 15;
  p.FSMC_CLKDivision = 8; 
  p.FSMC_DataLatency = 15;
  #endif
  p.FSMC_AccessMode = FSMC_AccessMode_A;

  FSMC_NORSRAMInitStructure.FSMC_Bank = FSMC_Bank1_NORSRAM3;
  FSMC_NORSRAMInitStructure.FSMC_DataAddressMux = FSMC_DataAddressMux_Disable;
  FSMC_NORSRAMInitStructure.FSMC_MemoryType = FSMC_MemoryType_SRAM;
  FSMC_NORSRAMInitStructure.FSMC_MemoryDataWidth = FSMC_MemoryDataWidth_16b;
  FSMC_NORSRAMInitStructure.FSMC_BurstAccessMode = FSMC_BurstAccessMode_Disable;
  FSMC_NORSRAMInitStructure.FSMC_WaitSignalPolarity = FSMC_WaitSignalPolarity_Low;
  FSMC_NORSRAMInitStructure.FSMC_WrapMode = FSMC_WrapMode_Disable;
  FSMC_NORSRAMInitStructure.FSMC_WaitSignalActive = FSMC_WaitSignalActive_BeforeWaitState;
  FSMC_NORSRAMInitStructure.FSMC_WriteOperation = FSMC_WriteOperation_Enable;
  FSMC_NORSRAMInitStructure.FSMC_WaitSignal = FSMC_WaitSignal_Disable;
  FSMC_NORSRAMInitStructure.FSMC_ExtendedMode = FSMC_ExtendedMode_Disable;
  FSMC_NORSRAMInitStructure.FSMC_WriteBurst = FSMC_WriteBurst_Disable;
  FSMC_NORSRAMInitStructure.FSMC_ReadWriteTimingStruct = &p;
  FSMC_NORSRAMInitStructure.FSMC_WriteTimingStruct = &p;

  FSMC_NORSRAMInit(&FSMC_NORSRAMInitStructure); 

  /* Enable FSMC Bank1_SRAM Bank */
  FSMC_NORSRAMCmd(FSMC_Bank1_NORSRAM3, ENABLE);  
}

使用就用绝对定位

__attribute__((at(addr)))

比如：

unsigned char buffer[10000]  __attribute__((at(0x6800000)))，即把数据buffer的地址定位到0x6800000