STM32F767 QSPI Flash Not Writing First Byte (S25FL256S)

[MADHU2]

Hi everyone,

I'm using an STM32F767 with an S25FL256S NOR flash over QSPI in indirect mode (HAL driver).

I'm trying to write the string "HELLO" at address 0x000000, but after programming and reading, I always get: FF 45 4C 4C 4F → "ELLO".

The first byte is always 0xFF. All other bytes are written and read correctly.

What I’ve already done:

• Verified Flash ID: 01 20 18 (correct)

• Erased the sector before writing

• Using 0x02 Page Program in 1-1-1 mode

• Set SIOOMode = QSPI_SIOO_INST_ONLY_FIRST_CMD

• Set FIFO threshold = 1

• Using indirect mode (HAL_QSPI_Command() + HAL_QSPI_Transmit())

• Test Code:
  char tx[] = "HELLO";
  QSPI_PageProgram(0x000000, (uint8_t*)tx, strlen(tx) + 1);
  QSPI_ReadData(0x000000, rx, strlen(tx) + 1);
  
  Why is the first byte not being written?

[MHoll.2]

Accoding to the S25FL256S Datasheet the 0x13 read command needs a 32 Bit Address, but You are sending only 24 Bit.

/*------------------------------------------------------------
  QSPI_ReadData
  Reads data starting at the given 24-bit address using the Read Data command (0x03).
  Datasheet reference: Section 11.4.1 (Normal Read).
------------------------------------------------------------*/
HAL_StatusTypeDef QSPI_ReadData(uint32_t address, uint8_t *pData, uint32_t Size)
{
    sCommand.Instruction     = CMD_READ_DATA;
    sCommand.InstructionMode = QSPI_INSTRUCTION_1_LINE;
    sCommand.Address         = address;
    sCommand.AddressMode     = QSPI_ADDRESS_1_LINE;
    sCommand.AddressSize     = QSPI_ADDRESS_24_BITS;
    sCommand.DataMode        = QSPI_DATA_1_LINE;
    sCommand.DummyCycles     = 0;  // Normal read does not require dummy cycles
    sCommand.NbData          = Size;

    if(HAL_QSPI_Command(&hqspi, &sCommand, HAL_QSPI_TIMEOUT_DEFAULT_VALUE) != HAL_OK)
        return HAL_ERROR;

    return HAL_QSPI_Receive(&hqspi, pData, HAL_QSPI_TIMEOUT_DEFAULT_VALUE);
}