本帖最后由 yuanmo 于 2016-7-19 09:38 编辑

  上面是官方和我的图纸     没能成功驱动， 不知道是板子布线的问题还是其他。 程序参照是官方的程序， 跑的90M。   怀疑是板子的走线的问题，但是不能驱动， 待会修改频率试试，  以下是配置代码


void SDRAM_Init(void)
{
  FMC_SDRAMInitTypeDef  FMC_SDRAMInitStructure;
  FMC_SDRAMTimingInitTypeDef  FMC_SDRAMTimingInitStructure;

  /* GPIO configuration for FMC SDRAM bank */
  SDRAM_GPIOConfig();

  /* Enable FMC clock */
  RCC_AHB3PeriphClockCmd(RCC_AHB3Periph_FMC, ENABLE);

/* FMC Configuration ---------------------------------------------------------*/
/* FMC SDRAM Bank configuration */   
  /* Timing configuration for 90 Mhz of SD clock frequency (180Mhz/2) */
  /* TMRD: 2 Clock cycles */
  FMC_SDRAMTimingInitStructure.FMC_LoadToActiveDelay    = 2;      
  /* TXSR: min=70ns (7x11.11ns) */
  FMC_SDRAMTimingInitStructure.FMC_ExitSelfRefreshDelay = 7;
  /* TRAS: min=42ns (4x11.11ns) max=120k (ns) */
  FMC_SDRAMTimingInitStructure.FMC_SelfRefreshTime      = 4;
  /* TRC:  min=70 (7x11.11ns) */        
  FMC_SDRAMTimingInitStructure.FMC_RowCycleDelay        = 7;         
  /* TWR:  min=1+ 7ns (1+1x11.11ns) */
  FMC_SDRAMTimingInitStructure.FMC_WriteRecoveryTime    = 2;      
  /* TRP:  20ns => 2x11.11ns */
  FMC_SDRAMTimingInitStructure.FMC_RPDelay              = 2;               
  /* TRCD: 20ns => 2x11.11ns */
  FMC_SDRAMTimingInitStructure.FMC_RCDDelay             = 2;

/* FMC SDRAM control configuration */
  FMC_SDRAMInitStructure.FMC_Bank = FMC_Bank2_SDRAM;
  /* Row addressing: [7:0] */
  FMC_SDRAMInitStructure.FMC_ColumnBitsNumber = FMC_ColumnBits_Number_8b;
  /* Column addressing: [11:0] */
  FMC_SDRAMInitStructure.FMC_RowBitsNumber = FMC_RowBits_Number_12b;
  FMC_SDRAMInitStructure.FMC_SDMemoryDataWidth = SDRAM_MEMORY_WIDTH;
  FMC_SDRAMInitStructure.FMC_InternalBankNumber = FMC_InternalBank_Number_4;
  FMC_SDRAMInitStructure.FMC_CASLatency = SDRAM_CAS_LATENCY;
  FMC_SDRAMInitStructure.FMC_WriteProtection = FMC_Write_Protection_Disable;
  FMC_SDRAMInitStructure.FMC_SDClockPeriod = SDCLOCK_PERIOD;  
  FMC_SDRAMInitStructure.FMC_ReadBurst = SDRAM_READBURST;
  FMC_SDRAMInitStructure.FMC_ReadPipeDelay = FMC_ReadPipe_Delay_1;
  FMC_SDRAMInitStructure.FMC_SDRAMTimingStruct = &FMC_SDRAMTimingInitStructure;

  /* FMC SDRAM bank initialization */
  FMC_SDRAMInit(&FMC_SDRAMInitStructure);

  /* FMC SDRAM device initialization sequence */
  SDRAM_InitSequence();
}


其他程序就不贴了 待会附件，  有个疑问， 若是要降频， 除了要修改 TMRD  还应该要修改哪些参数？