开发板FMC上挂载的是SDRAM，对应 的最主要的初始化函数是
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：
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