Unformatierte SD-Card lesen

  • Allgemein

Es gibt 6 Antworten in diesem Thema. Der letzte Beitrag () ist von UlliS.

    Unformatierte SD-Card lesen

    Hallo zusammen,

    ich möchte gerne den Inhalt einer SD-Card Byte für Byte oder Sektor für Sektor einlesen (RAW daten).
    Wieso ich das muss: Ich schreibe mit einen Mikrocontroller RAW Daten auf die SD-Card (Direktes schreiben) ohne das ich diese zuvor mit einen FAT-System formatiere.
    Ich kann die Daten über den Mikrocontroller wieder auslesen, da ich hier vollen Zugriff auf die Karte habe. Leider habe ich keine Ahnung wie ich das in VB6 oder VB.NET realisieren soll.

    Hat von Euch jemand Erfahrung oder so etwas schon mal gemacht?

    Ich hoffe ich habe die Frage einigermaßen verständlich gestellt.


    Grüße Ulli

    Ich habs jetzt mal in VB6 versucht, aber so ganz will das noch nicht :(
    Hier mal der Code vieleicht hast du einen Tipp was ich falsch mache, "J:" ist meine SD Karte.


    VB.NET-Quellcode

    1. Option Explicit
    3. Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (Destination As Any, Source As Any, ByVal Length As Long)
    4. Private Declare Function SetFilePointer Lib "kernel32" (ByVal hFile As Long, ByVal lDistanceToMove As Long, lpDistanceToMoveHigh As Long, ByVal dwMoveMethod As Long) As Long
    5. Private Declare Function ReadFile Lib "kernel32" (ByVal hFile As Long, lpBuffer As Any, ByVal nNumberOfBytesToRead As Long, lpNumberOfBytesRead As Long, ByVal lpOverlapped As Long) As Long
    6. Private Declare Function WriteFile Lib "kernel32" (ByVal hFile As Long, lpBuffer As Any, ByVal nNumberOfBytesToWrite As Long, lpNumberOfBytesWritten As Long, ByVal lpOverlapped As Long) As Long
    7. Private Declare Function CreateFile Lib "kernel32" Alias "CreateFileA" (ByVal lpFileName As String, ByVal dwDesiredAccess As Long, ByVal dwShareMode As Long, ByVal lpSecurityAttributes As Long, ByVal dwCreationDisposition As Long, ByVal dwFlagsAndAttributes As Long, ByVal hTemplateFile As Long) As Long
    8. Private Declare Function FlushFileBuffers Lib "kernel32" (ByVal hFile As Long) As Long
    9. Private Declare Function LockFile Lib "kernel32" (ByVal hFile As Long, ByVal dwFileOffsetLow As Long, ByVal dwFileOffsetHigh As Long, ByVal nNumberOfBytesToLockLow As Long, ByVal nNumberOfBytesToLockHigh As Long) As Long
    10. Private Declare Function UnlockFile Lib "kernel32" (ByVal hFile As Long, ByVal dwFileOffsetLow As Long, ByVal dwFileOffsetHigh As Long, ByVal nNumberOfBytesToUnlockLow As Long, ByVal nNumberOfBytesToUnlockHigh As Long) As Long
    11. Private Declare Function CloseHandle Lib "kernel32" (ByVal hObject As Long) As Long
    13. Private Const GENERIC_READ = &H80000000
    14. Private Const GENERIC_WRITE = &H40000000
    15. Private Const FILE_SHARE_READ = &H1
    16. Private Const FILE_SHARE_WRITE = &H2
    17. Private Const OPEN_EXISTING = 3
    18. Private Const INVALID_HANDLE_VALUE = -1&
    19. Private Const BytesPerSector = 512
    20. Private Const FILE_BEGIN = 0
    23. Private Function DirectWriteDriveNT(ByVal sDrive As String, ByVal iStartSec As Long, ByVal iOffset As Long, ByVal sWrite As String) As Boolean
    24. Dim hDevice As Long
    25. Dim abBuff() As Byte
    26. Dim nSectors As Long
    27. Dim nRead As Long
    28. Dim ab() As Byte
    29. nSectors = Int((iOffset + Len(sWrite) - 1) / BytesPerSector) + 1
    30. hDevice = CreateFile(sDrive, GENERIC_READ Or GENERIC_WRITE, FILE_SHARE_READ Or FILE_SHARE_WRITE, 0&, OPEN_EXISTING, 0&, 0&)
    31. If hDevice = INVALID_HANDLE_VALUE Then Exit Function
    32. abBuff = DirectReadDriveNT(sDrive, iStartSec, 0, nSectors * BytesPerSector)
    33. ab = StrConv(sWrite, vbFromUnicode)
    34. CopyMemory abBuff(iOffset), ab(0), Len(sWrite)
    35. Call SetFilePointer(hDevice, iStartSec * BytesPerSector, 0, FILE_BEGIN)
    36. Call LockFile(hDevice, LoWord(iStartSec * BytesPerSector), HiWord(iStartSec * BytesPerSector), LoWord(nSectors * BytesPerSector), HiWord(nSectors * BytesPerSector))
    37. DirectWriteDriveNT = WriteFile(hDevice, abBuff(0), UBound(abBuff) + 1, nRead, 0&)
    38. Call FlushFileBuffers(hDevice)
    39. Call UnlockFile(hDevice, LoWord(iStartSec * BytesPerSector), HiWord(iStartSec * BytesPerSector), LoWord(nSectors * BytesPerSector), HiWord(nSectors * BytesPerSector))
    40. CloseHandle hDevice
    41. End Function
    44. Private Function DirectReadDriveNT(ByVal sDrive As String, ByVal iStartSec As Long, ByVal iOffset As Long, ByVal cBytes As Long) As Variant
    45. Dim hDevice As Long
    46. Dim nSectors As Long
    47. Dim nRead As Long
    48. Dim abResult() As Byte
    49. nSectors = Int((iOffset + cBytes - 1) / BytesPerSector) + 1
    50. hDevice = CreateFile(sDrive, GENERIC_READ Or GENERIC_WRITE, FILE_SHARE_READ Or FILE_SHARE_WRITE, 0&, OPEN_EXISTING, 0&, 0&)
    51. If hDevice = INVALID_HANDLE_VALUE Then Exit Function
    52. Call SetFilePointer(hDevice, iStartSec * BytesPerSector, 0, FILE_BEGIN)
    53. ReDim abResult(cBytes - 1)
    54. ReDim abBuff(nSectors * BytesPerSector - 1)
    55. Call ReadFile(hDevice, abBuff(0), UBound(abBuff) + 1, nRead, 0&)
    56. CloseHandle hDevice
    57. CopyMemory abResult(0), abBuff(iOffset), cBytes
    58. DirectReadDriveNT = abResult '(0)
    59. End Function
    62. Private Function LoWord(ByVal dw As Long) As Integer
    63. If dw And &H8000& Then
    64. LoWord = dw Or &HFFFF0000
    65. Else
    66. LoWord = dw And &HFFFF&
    67. End If
    68. End Function
    71. Private Function HiWord(ByVal dw As Long) As Integer
    72. HiWord = (dw And &HFFFF0000) \ 65536
    73. End Function
    76. Private Function hex2ascii(ByVal hextext As String) As String
    77. Dim y As Integer
    78. Dim num
    79. Dim Value
    80. For y = 1 To Len(hextext)
    81. num = Mid(hextext, y, 2)
    82. Value = Value & Chr(Val("&h" & num))
    83. y = y + 1
    84. Next y
    85. hex2ascii = Value
    86. End Function
    89. Private Sub Command1_Click()
    91. 'DirectReadDriveNT(ByVal sDrive As String, ByVal iStartSec As Long, ByVal iOffset As Long, ByVal cBytes As Long) As Variant
    92. Text1.Text = DirectReadDriveNT("\\?\J:", 0, 0, 1)
    94. End Sub
    96. Private Sub Command2_Click()
    98. ' Write hex "EB" to the first byte of the partition boot sector of volume H:
    99. DirectWriteDriveNT "\\?\J:", 0, 0, hex2ascii("eb")
    102. End Sub



    Oh das wusste ich gar nicht das bei den Longs ein Unterschied besteht, wo liegt der genau?

    Danke nochmals für die Hilfe!


    Grüße Ulli

    Hi
    Longs sind in VB6 Int32 (also Ganzzahlen, die aus 32 Bits bestehen). Diese haben den Maximalwert 2^31 - 1 und den Minimalwert - 2^31 (Somit also 2^32 verschiedene Werte). In VB.Net ist ein Long ein Int64 und somit eine Ganzzahl, die aus 64 Bits besteht. Somit sind halt dann die Werte -2^63 bis 2^63 -1 möglich.

    Gruß
    ~blaze~

Facebook
Telefonspende