STM32F469I---入门FMC的使用

2021-10-14 11:08

【STM32F469I试用】入门（六）：FMC的使用【转】

开发板FMC上挂载的是SDRAM，对应的最主要的初始化函数是
BSP_SDRAM_Init();

与其他外设的初始化一样，初始化过程也是在对结构体sdramHandle的赋值。
这个结构体的类型是SDRAM_HandleTypeDef
这是一个比较简单的结构体
typedef struct
{
  FMC_SDRAM_TypeDef          *Instance;  /*!< Register base address                */

  FMC_SDRAM_InitTypeDef       Init;    /*!< SDRAM device configuration parameters */

  __IO HAL_SDRAM_StateTypeDef State;    /*!< SDRAM access state                   */

  HAL_LockTypeDef             Lock;    /*!< SDRAM locking object                */

  DMA_HandleTypeDef          *hdma;    /*!< Pointer DMA handler                */

}SDRAM_HandleTypeDef;

对FMC初始化的硬件相关的函数是HAL_SDRAM_Init(&sdramHandle, &Timing)
而其中再主要的是函数HAL_StatusTypeDef FMC_SDRAM_Init(FMC_SDRAM_TypeDef *Device, FMC_SDRAM_InitTypeDef *Init)；
  if (Init->SDBank != FMC_SDRAM_BANK2)
  {
tmpr1 = Device->SDCR[FMC_SDRAM_BANK1];

/* Clear NC, NR, MWID, NB, CAS, WP, SDCLK, RBURST, and RPIPE bits */
tmpr1 &= ((uint32_t)~(FMC_SDCR1_NC  | FMC_SDCR1_NR | FMC_SDCR1_MWID | \
                     FMC_SDCR1_NB  | FMC_SDCR1_CAS | FMC_SDCR1_WP | \
                     FMC_SDCR1_SDCLK | FMC_SDCR1_RBURST | FMC_SDCR1_RPIPE));

tmpr1 |= (uint32_t)(Init->ColumnBitsNumber |\
                                             Init->RowBitsNumber    |\
                                             Init->MemoryDataWidth |\
                                             Init->InternalBankNumber |\
                                             Init->CASLatency       |\
                                             Init->WriteProtection |\
                                             Init->SDClockPeriod    |\
                                             Init->ReadBurst       |\
                                             Init->ReadPipeDelay
                                             );
Device->SDCR[FMC_SDRAM_BANK1] = tmpr1;
  }
  else /* FMC_Bank2_SDRAM */
  {
tmpr1 = Device->SDCR[FMC_SDRAM_BANK1];

/* Clear NC, NR, MWID, NB, CAS, WP, SDCLK, RBURST, and RPIPE bits */
tmpr1 &= ((uint32_t)~(FMC_SDCR1_NC  | FMC_SDCR1_NR | FMC_SDCR1_MWID | \
                        FMC_SDCR1_NB  | FMC_SDCR1_CAS | FMC_SDCR1_WP | \
                        FMC_SDCR1_SDCLK | FMC_SDCR1_RBURST | FMC_SDCR1_RPIPE));

tmpr1 |= (uint32_t)(Init->SDClockPeriod    |\
                     Init->ReadBurst       |\
                     Init->ReadPipeDelay);

tmpr2 = Device->SDCR[FMC_SDRAM_BANK2];

/* Clear NC, NR, MWID, NB, CAS, WP, SDCLK, RBURST, and RPIPE bits */
tmpr2 &= ((uint32_t)~(FMC_SDCR1_NC  | FMC_SDCR1_NR | FMC_SDCR1_MWID | \
                        FMC_SDCR1_NB  | FMC_SDCR1_CAS | FMC_SDCR1_WP | \
                        FMC_SDCR1_SDCLK | FMC_SDCR1_RBURST | FMC_SDCR1_RPIPE));

tmpr2 |= (uint32_t)(Init->ColumnBitsNumber |\
                     Init->RowBitsNumber    |\
                     Init->MemoryDataWidth |\
                     Init->InternalBankNumber |\
                     Init->CASLatency       |\
                     Init->WriteProtection);

Device->SDCR[FMC_SDRAM_BANK1] = tmpr1;
Device->SDCR[FMC_SDRAM_BANK2] = tmpr2;
  }

要注意。BANK1对应 BANK0，BANK2对应 BANK1
#define FMC_SDRAM_BANK1                      ((uint32_t)0x00000000)
#define FMC_SDRAM_BANK2                      ((uint32_t)0x00000001)

其本质，不过是对寄存器SDCR的配置。

还有一个寄存器STDR。它的配置在函数FMC_SDRAM_Timing_Init(hsdram->Instance, Timing, hsdram->Init.SDBank);中。
这两个函数完成了对SRAM的基本配置。

最后对SRAM进行读写结果：