Correct usage of Flash_ReadOnce?

[javiersoriano]

I am following the flash_erase_program_verifiy example with a FRDMK82F board.

I am not sure what I am missing, I suppose I should be able to read back the exact values that have been programmed; i.e. the contents of buffer = {0, 1, 2, 3 ...}

Before the end, I added the following lines to the source file:

    uint32_t readback[BUFFER_LEN]; /* Buffer for program */

    result = FLASH_ReadOnce(&flashDriver, destAdrss, readback, sizeof(buffer));

    if (kStatus_FLASH_Success != result)

    {

        error_trap();

    }

    for (i = 0; i < BUFFER_LEN; i++)

    {

        PRINTF("%d %x %x\r\n", i, buffer[i], readback[i]);

    }

and the output I get is the following:

Flash Example Start

Flash Information:

Total Program Flash Size:      256 KB, Hex: (0x40000)

Program Flash Sector Size:     4 KB, Hex: (0x1000)

There is no D-Flash (FlexNVM) on this Device.

There is no Enhanced EEPROM (EEE) on this Device.

Flash is UNSECURE!

Erase a sector of flash

Successfully Erased Sector 0x3f000 -> 0x40000

Program a buffer to a sector of flash

Successfully Programmed and Verified Location 0x3f000 -> 0x3f010

0 0 ffffffff

1 1 2002ffac

2 2 ffffffff

3 3 2002ff3c

End of Flash Example

If anyone could shed some light on this matter, it would be appreciated.

Original Attachment has been moved to: flash_erase_program_verify.c.zip

[jeremyzhou]

Hi Javier,

I've attached the code of the FLASH_ReadOnce function and you can see the exactly meaning of the kind of parameters, I don't think the usage of your demo is compatible with it.

status_t FLASH_ReadOnce(flash_config_t *config, uint32_t index, uint32_t *dst, uint32_t lengthInBytes)
{
    status_t returnCode;
    if ((config == NULL) || (dst == NULL))
    {
        return kStatus_FLASH_InvalidArgument;
    }
    /* pass paramters to FTFx */
    kFCCOBx[0] = BYTES_JOIN_TO_WORD_1_1_2(FTFx_READ_ONCE, index, 0xFFFFU);
    /* calling flash command sequence function to execute the command */
    returnCode = flash_command_sequence(config);
    if (kStatus_FLASH_Success == returnCode)
    {
        *dst = kFCCOBx[1];
/* Note: Have to seperate the first index from the rest if it equals 0
 *       to avoid a pointless comparison of unsigned int to 0 compiler warning */
#if FLASH_PROGRAM_ONCE_IS_8BYTES_UNIT_SUPPORT
#if FLASH_PROGRAM_ONCE_IS_4BYTES_UNIT_SUPPORT
        if (((index == FLASH_PROGRAM_ONCE_MIN_ID_8BYTES) ||
             /* Range check */
             ((index >= FLASH_PROGRAM_ONCE_MIN_ID_8BYTES + 1) && (index <= FLASH_PROGRAM_ONCE_MAX_ID_8BYTES))) &&
            (lengthInBytes == 8))
#endif /* FLASH_PROGRAM_ONCE_IS_4BYTES_UNIT_SUPPORT */
        {
            *(dst + 1) = kFCCOBx[2];
        }
#endif /* FLASH_PROGRAM_ONCE_IS_8BYTES_UNIT_SUPPORT */
    }
    return returnCode;
}

Have a great day,
Ping

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[javiersoriano]

Hi Ping,

Thanks for the quick answer and then pointers. I went and looked more carefully to the API description.

It states:

     Read Program Once Field through parameters

    This function reads the read once feild with given index and length.

If I understand correctly, it means that I do not read the actual data back, but whatever this field is and means. I suppose this given that there are Flash_Program, Flash_ProgramOnce, and Flash_ReadOnce functions. What I would expect then is a Flash_Read function, but I don't think is there, is it?

Does it mean that I cannot read the flash at all? I'm fairly new to this,  so I may be missing something very obvious.

Thanks in advance.

[jeremyzhou]

Hi Javier,

Thanks for your reply.

In your code, the second parameter is the destAdree instead of the index. I think it's not correct.

For instance, to read the 0x80~0x83, you can use the following code.

  uint32_t readback[4]; /* Buffer for program */
    result = FLASH_ReadOnce(&flashDriver, 0x20, readback, sizeof(readback));
    if (kStatus_FLASH_Success != result)
    {
        error_trap();
    }

Hope it helps.
Have a great day,
Ping

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Note: If this post answers your question, please click the Correct Answer button. Thank you!
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[javiersoriano]

Hi Ping,

Thanks for the pointers. I think I complicated the issue too much. In the end, I solved it by doing a simple memcpy:

    // Read expected signature here.

    PRINTF("DATA_ADDR: %x\r\n", DATA_ADDR);

    uint8_t data[DATA_SIZE];

    memcpy(data, (uint8_t*)DATA_ADDR, DATA_SIZE);

because I was not interested in the Read Once field, but in the data itself.

Thanks again for the help!