sdram read/write issue with stm32h7 microcontroller

Question

I am using stm32h743ii microcontroller and interfaced with a external sdram of 512mb ( micron - MT48LC64M8A2P) .

I have created the initial code using cubemx and performing basic read write test code by taking a reference of example code provided with stm32h7 firmware. Initialization code :

   void MX_FMC_Init(void)
{
  FMC_SDRAM_TimingTypeDef SdramTiming;

  /** Perform the SDRAM1 memory initialization sequence
  */
  hsdram1.Instance = FMC_SDRAM_DEVICE;
  /* hsdram1.Init */
  hsdram1.Init.SDBank = FMC_SDRAM_BANK1;
  hsdram1.Init.ColumnBitsNumber = FMC_SDRAM_COLUMN_BITS_NUM_11;
  hsdram1.Init.RowBitsNumber = FMC_SDRAM_ROW_BITS_NUM_13;
  hsdram1.Init.MemoryDataWidth = FMC_SDRAM_MEM_BUS_WIDTH_8;
  hsdram1.Init.InternalBankNumber = FMC_SDRAM_INTERN_BANKS_NUM_4;
  hsdram1.Init.CASLatency = FMC_SDRAM_CAS_LATENCY_1;
  hsdram1.Init.WriteProtection = FMC_SDRAM_WRITE_PROTECTION_DISABLE;
  hsdram1.Init.SDClockPeriod = FMC_SDRAM_CLOCK_PERIOD_2;
  hsdram1.Init.ReadBurst = FMC_SDRAM_RBURST_ENABLE;
  hsdram1.Init.ReadPipeDelay = FMC_SDRAM_RPIPE_DELAY_0;
  /* SdramTiming */
  SdramTiming.LoadToActiveDelay = 2;
  SdramTiming.ExitSelfRefreshDelay =8;
  SdramTiming.SelfRefreshTime = 5;
  SdramTiming.RowCycleDelay = 7;
  SdramTiming.WriteRecoveryTime =3;
  SdramTiming.RPDelay = 2;
  SdramTiming.RCDDelay = 2;

  if (HAL_SDRAM_Init(&hsdram1, &SdramTiming) != HAL_OK)
  {
    _Error_Handler(__FILE__, __LINE__);
  }

}

All the timing parameters is configured by taking reference from the datasheet.

Issue : I am testing the read write by writing 1 to 4096 index to bank 1 and then read back from the same memory. When I test this I am getting the written data is multiplied with a factor of 256. Eg, If I write 1 to any memory address then I read back it as 256.

davidra7 davidra7 · Accepted Answer · 2020-05-18T07:49:22

You need to initialize SDRAM. Try using next code ( you might need to change refresh count and change to CAS latency to 3 )

void MX_SDRAM_InitEx(void)
{
    FMC_SDRAM_CommandTypeDef Command;
  __IO uint32_t tmpmrd = 0;

  /* Step 1: Configure a clock configuration enable command */
  Command.CommandMode            = FMC_SDRAM_CMD_CLK_ENABLE;
  Command.CommandTarget          =  FMC_SDRAM_CMD_TARGET_BANK1;
  Command.AutoRefreshNumber      = 1;
  Command.ModeRegisterDefinition = 0;

  /* Send the command */
  HAL_SDRAM_SendCommand(&hsdram1, &Command, SDRAM_TIMEOUT);

  /* Step 2: Insert 100 us minimum delay */
  /* Inserted delay is equal to 1 ms due to systick time base unit (ms) */
  HAL_Delay(1);

  /* Step 3: Configure a PALL (precharge all) command */
  Command.CommandMode            = FMC_SDRAM_CMD_PALL;
  Command.CommandTarget          = FMC_SDRAM_CMD_TARGET_BANK1;
  Command.AutoRefreshNumber      = 1;
  Command.ModeRegisterDefinition = 0;

  /* Send the command */
  HAL_SDRAM_SendCommand(&hsdram1, &Command, SDRAM_TIMEOUT);

  /* Step 4: Configure an Auto Refresh command */
  Command.CommandMode            = FMC_SDRAM_CMD_AUTOREFRESH_MODE;
  Command.CommandTarget          = FMC_SDRAM_CMD_TARGET_BANK1;
  Command.AutoRefreshNumber      = 8;
  Command.ModeRegisterDefinition = 0;

  /* Send the command */
  HAL_SDRAM_SendCommand(&hsdram1, &Command, SDRAM_TIMEOUT);

  /* Step 5: Program the external memory mode register */
  tmpmrd = (uint32_t)SDRAM_MODEREG_BURST_LENGTH_1          |\
                     SDRAM_MODEREG_BURST_TYPE_SEQUENTIAL   |\
                     SDRAM_MODEREG_CAS_LATENCY_3           |\
                     SDRAM_MODEREG_OPERATING_MODE_STANDARD |\
                     SDRAM_MODEREG_WRITEBURST_MODE_SINGLE;

  Command.CommandMode            = FMC_SDRAM_CMD_LOAD_MODE;
  Command.CommandTarget          = FMC_SDRAM_CMD_TARGET_BANK1;
  Command.AutoRefreshNumber      = 1;
  Command.ModeRegisterDefinition = tmpmrd;

  /* Send the command */
  HAL_SDRAM_SendCommand(&hsdram1, &Command, SDRAM_TIMEOUT);

  /* Step 6: Set the refresh rate counter */
  /* Set the device refresh rate */
  HAL_SDRAM_ProgramRefreshRate(&hsdram1, REFRESH_COUNT);
}


#define REFRESH_COUNT                           1386 // 1845

#define SDRAM_TIMEOUT                            ((uint32_t)0xFFFF)
#define SDRAM_MODEREG_BURST_LENGTH_1             ((uint16_t)0x0000)
#define SDRAM_MODEREG_BURST_LENGTH_2             ((uint16_t)0x0001)
#define SDRAM_MODEREG_BURST_LENGTH_4             ((uint16_t)0x0002)
#define SDRAM_MODEREG_BURST_LENGTH_8             ((uint16_t)0x0004)
#define SDRAM_MODEREG_BURST_TYPE_SEQUENTIAL      ((uint16_t)0x0000)
#define SDRAM_MODEREG_BURST_TYPE_INTERLEAVED     ((uint16_t)0x0008)
#define SDRAM_MODEREG_CAS_LATENCY_2              ((uint16_t)0x0020)
#define SDRAM_MODEREG_CAS_LATENCY_3              ((uint16_t)0x0030)
#define SDRAM_MODEREG_OPERATING_MODE_STANDARD    ((uint16_t)0x0000)
#define SDRAM_MODEREG_WRITEBURST_MODE_PROGRAMMED ((uint16_t)0x0000)
#define SDRAM_MODEREG_WRITEBURST_MODE_SINGLE     ((uint16_t)0x0200)

sdram read/write issue with stm32h7 microcontroller

1 Answers