B4J Question byte in binary format to number conversion after reading on usb

Sub AStreams_NewData (Buffer() As Byte)
    Log("Received " & Buffer.Length & " bytes")
    For I = 0 to Buffer.Length - 1
        Log(I & Tab & Bit.And(Buffer(I), 0xFF))    'convert signed bytes -128..127 to unsigned 0..255'
    Next
End Sub

]Sub AStreams_NewData (Buffer() As Byte)
    Dim NumBytes As Int = Buffer.Length
    If NumBytes > 12 Then
        NumBytes = 12
    End If
 
    Dim N(NumBytes) As Int
    For I = 0 to NumBytes - 1
        N(I) = Bit.And(Buffer(I), 0xFF)    'convert signed bytes -128..127 to unsigned 0..255'
    Next
 
    Log(N.As(List))    'to display an Array, pretend it's a List
End Sub

Sub AStreams_NewData (Buffer() As Byte)
    Log(Buffer.As(List))    'to display an Array, pretend it's a List
End Sub

Sub PacketOk(Buffer() As Byte) As Boolean
    If Buffer.Length <> 12 Then Return False    'or < 12 ?
    If Buffer(0) <> 0xFA Then Return False    'START byte    '
    If Buffer(11) <> 0xFD Then Return False    'STOP byte
 
    Dim CheckValue As Byte = 0
    For I = 1 to 10    'not including START and STOP bytes
        CheckValue = Bit.XOR(CheckValue, Buffer(I))
    Next
    If CheckValue <> 0 Then Return False
 
    Return True    'if gets to here, must be good
End Sub

Sub Process_Globals
    Private fx As JFX
    Private MainForm As Form
    Private xui As XUI
    Private Button1 As B4XView
    
    Private sp As Serial
    Private astream As AsyncStreams
    Private SerialBuffer As String

    Dim timer1 As Timer
    Dim counter1 As Int = 0
    Dim bytesSec As Int = 0
    
    'Dim SerialBuffer As String ' replaced by B4XBytesBuilder
    
    Dim bBuilder As B4XBytesBuilder
End Sub

Sub AppStart (Form1 As Form, Args() As String)
    MainForm = Form1
    MainForm.RootPane.LoadLayout("Layout1")
    MainForm.Show
    
    timer1.Initialize("timer1", 1000)
    timer1.Enabled = True
    SerialBuffer=""
    
    sp.Initialize("sp")
 
    Log(sp.ListPorts)
 
    'SerialBuffer = ""
    bBuilder.Initialize
    bBuilder.Clear
    'Dim searchFor() As Byte = Array As Byte(0xFA,0xFD)
    'Log("0" & searchFor(0))
    'Log("1" & searchFor(1))
    'Return
    If sp.ListPorts.Size > 0 Then
        sp.Open(sp.ListPorts.Get(0))
        sp.SetParams(9600, 8, 1, 0) ' baud: 9600, 115200, 500000
 
        astream.Initialize(sp.GetInputStream, sp.GetOutputStream, "astream")
    Else
        Log("No serial port found")
    End If
 
End Sub

Sub Button1_Click
    xui.MsgboxAsync("Hello World!", "B4X")
End Sub

Sub timer1_tick
    bytesSec = counter1
    counter1 = 0
    Log("bytes/Sec: " & bytesSec)
End Sub

Sub AStream_NewData (Buffer() As Byte)
    ' Old way to avoid breaking the message (replaced by B4XBytesBuilder):
    
    SerialBuffer =  SerialBuffer & BytesToString(Buffer, 0, Buffer.Length, "UTF8")
    Log("Lung.  Buffer: " & SerialBuffer.Length & CRLF)
    Log("Serial Buffer" & SerialBuffer)
    
    Return
    

End Sub

Sub Process_Globals
    Dim PacketSize As Int = 12
    Dim PacketBuffer As String
  
    Dim StartOfPacketByte As Int = 0xFA
    Dim EndOfPacketByte As Int = 0xFD
End Sub

Sub AStreams_NewData(Buffer() As Byte)
    '''Log("NewData" & TAB & DateTime.Now & TAB & B.As(List))
 
    For Each ChByte As Byte In Buffer    'ChByte is -128..127
        Dim ChInt As Int = Bit.And(ChByte, 0xFF)    'ChInt is 0..255

        PacketBuffer = PacketBuffer & Chr(ChInt)    'add next packet byte
        If PacketBuffer.Length > PacketSize Then    'limit to max packet size
            PacketBuffer = PacketBuffer.SubString(1)
        End If
      
        If ChInt = EndOfPacketByte Then    'if we are at end of packet (note: could be checksum byte)
            If PacketBuffer.Length = PacketSize Then    'and we plausibly have entire packet
                If PacketBuffer.StartsWith(Chr(StartOfPacketByte)) Then    'and the packet starts with correct byte
                    HandlePacket(PacketBuffer)
                    PacketBuffer = ""    'none of the packet just processed, will be used in any subsequent packets
                End If
            End If
        End If
    Next
End Sub

Sub HandlePacket(Packet as String)
    Dim sb As StringBuilder
    sb.Initialize
    For I = 0 To Packet.Length - 1
        If I <> 0 Then sb.Append(" ")
        sb.Append(Asc(Packet.CharAt(I)))
    Next
    Log("HandlePacket" & TAB & sb.ToString)
End Sub