STM32F469 with AS4C4M32S SDRAM only able to write first byte.

[AShar.7]

Hi,

I have made a custom board that features a STM32F469NI MCU coupled with AS4C4M32S SDRAM.

Following are the SDRAM timing and register set information:

hsdram1.Instance = FMC_SDRAM_DEVICE;
  /* hsdram1.Init */
  hsdram1.Init.SDBank = FMC_SDRAM_BANK1;
  hsdram1.Init.ColumnBitsNumber = FMC_SDRAM_COLUMN_BITS_NUM_8;
  hsdram1.Init.RowBitsNumber = FMC_SDRAM_ROW_BITS_NUM_12;
  hsdram1.Init.MemoryDataWidth = FMC_SDRAM_MEM_BUS_WIDTH_32;
  hsdram1.Init.InternalBankNumber = FMC_SDRAM_INTERN_BANKS_NUM_4;
  hsdram1.Init.CASLatency = FMC_SDRAM_CAS_LATENCY_3;
  hsdram1.Init.WriteProtection = FMC_SDRAM_WRITE_PROTECTION_DISABLE;
  hsdram1.Init.SDClockPeriod = FMC_SDRAM_CLOCK_PERIOD_2;
  hsdram1.Init.ReadBurst = FMC_SDRAM_RBURST_DISABLE;
  hsdram1.Init.ReadPipeDelay = FMC_SDRAM_RPIPE_DELAY_0;
  /* SdramTiming */
  SdramTiming.LoadToActiveDelay = 2;
  SdramTiming.ExitSelfRefreshDelay = 7;
  SdramTiming.SelfRefreshTime = 4;
  SdramTiming.RowCycleDelay = 6;
  SdramTiming.WriteRecoveryTime = 2;
  SdramTiming.RPDelay = 2;
  SdramTiming.RCDDelay = 2;
 
  if (HAL_SDRAM_Init(&hsdram1, &SdramTiming) != HAL_OK)
  {
    Error_Handler( );
  }
 
  /* USER CODE BEGIN FMC_Init 2 */
 
	FMC_SDRAM_CommandTypeDef cmd = { 0 };
 
	cmd.CommandMode = FMC_SDRAM_CMD_CLK_ENABLE;
	cmd.CommandTarget = FMC_SDRAM_CMD_TARGET_BANK1;
	cmd.AutoRefreshNumber = 1;
	cmd.ModeRegisterDefinition = 0;
	HAL_SDRAM_SendCommand(&hsdram1, &cmd, 0xFFFF);
 
	HAL_Delay(100);
 
	cmd.CommandMode = FMC_SDRAM_CMD_PALL;
	cmd.CommandTarget = FMC_SDRAM_CMD_TARGET_BANK1;
	cmd.AutoRefreshNumber = 1;
	cmd.ModeRegisterDefinition = 0;
	HAL_SDRAM_SendCommand(&hsdram1, &cmd, 0xFFFF);
 
 
	cmd.CommandMode = FMC_SDRAM_CMD_AUTOREFRESH_MODE;
	cmd.CommandTarget = FMC_SDRAM_CMD_TARGET_BANK1;
	cmd.AutoRefreshNumber = 8;
	cmd.ModeRegisterDefinition = 0;
	HAL_SDRAM_SendCommand(&hsdram1, &cmd, 0xFFFF);
 
 
	cmd.CommandMode = FMC_SDRAM_CMD_LOAD_MODE;
	cmd.CommandTarget = FMC_SDRAM_CMD_TARGET_BANK1;
	cmd.AutoRefreshNumber = 1;
	cmd.ModeRegisterDefinition = (uint32_t) 0x230; //also tried 0x231
	HAL_SDRAM_SendCommand(&hsdram1, &cmd, 0xFFFF);
 
 
 
	//Setup SDRAM Refresh Timer Register with the delay between refresh cycles of the SDRAM, this is SDRAM specific.
	HAL_SDRAM_ProgramRefreshRate(&hsdram1, 1404); //Tried 1386

This same code works when running on a STM32F469-I DISCOVERY Board but fails when It is run on my custom carrier board.

On my board, whenever I write to any SDRAM address, only the first byte is READ/WRITTEN to, for example when I write 0x00 to address 0xC0000000, the data at that address when monitored under debugging contains 0x48129100 i.e first 3 BYTES are random garbage and only the last byte is written correctly(0x00), and suppose If i write 0xAA to the same address the data there when monitored contains the value 0x481291AA.

This is true to every address that I read/write to/from the external SDRAM.

Only the last byte is written/read.

The custom board schematic and PCB layout is identical to the STM32F469-I DISCO board.

Only difference is the RAM chip which instead of being MICRON one is Alliance Memory's AS4C4M32S .

What can be the issue of such a problem?