#眉標=GPS開發範例
#副標=定位系統運作原理與開發實作
#大標=自製GPS衛星定位系統
#作者=文／陳秀玲



==<box>===========
程式1
Dim objGGA As GGA  '宣告GGA類型的物件變數
Dim objVTG As VTG  '宣告VTG類型的物件變數
Dim objGSV As GSV   '宣告GSV類型的物件變數

Private Sub Form_Load()
MSComm1.CommPort = 1   '設定連接埠為COM1
MSComm1.Settings = "4800,n,8,1"    
'4800速率、無同位檢查、8資料位元、停止位元1
MSComm1.PortOpen = True '開啟連接埠COM1
MSComm1.RThreshold = 128
End Sub

Private Sub Form_Unload(Cancel As Integer)
 MSComm1.PortOpen = False '關閉連接埠COM1
End Sub

'時間事件程序，每半秒鐘執行一次
Private Sub Timer1_Timer()
Dim strBuffer As String

If MSComm1.InBufferCount >= 1 Then 
 'RS-232的輸入暫存區資料>1，則執行下一段
strBuffer = MSComm1.Input 
'strBuffer等於輸入的資料
Call ParseSentence(strBuffer, objGGA, objVTG, objGSV)  
'呼叫顯示數據物件的副程式
'將項目文字指定給Text
Text1.Text = (Left(objGGA.時間, 2) + 8) & ":" 
& Mid(objGGA.時間, 3, 2)
Text2.Text = objGGA.使用中的衛星顆數
Text3.Text = Left(objGGA.經度, 2) & ":" 
& Mid(objGGA.經度, 3, 2) & "." 
& Mid(objGGA.經度, 6, 2) & ":" 
& Mid(objGGA.經度, 8, 2) & ":" 
& objGGA.strNSIndicator
Text4.Text = Left(objGGA.緯度, 3) & ":" 
& Mid(objGGA.緯度, 4, 2) & "."
& Mid(objGGA.緯度, 7, 2) & ":" 
& Mid(objGGA.緯度, 9, 2) & ":"
& objGGA.strEWIndicator
Text5.Text = objGGA.高度 & " "
& objGGA.strAltUnits
Text6.Text = objVTG.相對位移速度1 & " " 
& objVTG.strSpeedUnit1
Text7.Text = objVTG.相對位移速度2 & " " 
& objVTG.strSpeedUnit2
If objGSV.StrSeq = "1" Then
Text8.Text = objGSV.衛星仰角
Text9.Text = objGSV.衛星方位角
Text10.Text = objGSV.天空中衛星總數
End If

' 顯示執行畫面的字串=時間
Form1.Caption = "KxLan GPS Module. UTC Time = " 
& (Left(objGGA.時間, 2) + 8) 
& ":" & Mid(objGGA.時間, 3, 2)
        
End If
End Sub
==<end>==============




==<box>===========
程式2
Public Type GGA
時間 As String
經度 As Variant
strNSIndicator As String
緯度 As Variant
strEWIndicator As String
strPositionFix As String
使用中的衛星顆數 As String
strIIDOP As String
高度 As String
strAltUnits As String
strGeoid As String
strSepUnits As String
strDgpsAge As String
strDgpsid As String
strchecksum As String
strTerminator As String
End Type

Public Type VTG
strCourse1 As String
strReference1 As String
strCourse2 As String
strReference2 As String
相對位移速度1 As String
相對位移速度2 As String
strSpeedUnit1 As String
strSpeedUnit2 As String
End Type

Public Type GSV
StrNoMessages As String
StrSeq As String
StrSatsinview As String
天空中衛星總數 As String
衛星仰角 As String
衛星方位角 As String
StrSNR1 As String
StrSatId2 As String
StrElevation2 As String
StrAzimuth2 As String
StrSNR2 As String
StrSatId3 As String
StrElevation3 As String
StrAzimuth3 As String
StrSNR3 As String
StrSatId4 As String
StrElevation4 As String
StrAzimuth4 As String
StrSNR4 As String
End Type

Public Sub ParseSentence(InBuff As String, 
MyGGA As GGA, Myvtg As VTG, MyGSV As GSV)
    Dim aryData(25)
    Dim x, z, st, fn, intst As Integer
    Dim strSentence, strTemp, strDummy As String
    
    '抓訊號的開頭 ”$”
    For x = 1 To Len(InBuff)
        If Mid(InBuff, x, 1) = "$" Then
            st = x
            Exit For
        End If
    Next
    
    '抓訊號的結尾(vbcr換格字元).
    For x = st To Len(InBuff)
        If Mid(InBuff, x, 1) = vbCr Then
            fn = x
            Exit For
        End If
    Next
    
    ' Use st and fn to slice the string to a sentence.
     strSentence = Mid(InBuff, st, fn - st)
    
    ' 算訊號裡有幾個逗號，存到intComm
    For x = 1 To Len(strSentence)
        If Mid(strSentence, x, 1) = "," Then
            intComma = intComma + 1
        End If
    Next
' 把每個逗號之間的資料存到所對應的矩陣，
如$GPGGA第一筆資料所對應的矩陣為aryData(1)，
然後把矩陣資料存到strUttcTime字串.
   z = 8
   For x = 1 To intComma
   Do While Mid(strSentence, z, 1) <> "," 
   And Mid(strSentence, z, 1) <> "*"
   aryData(x) = aryData(x) & Mid(strSentence, z, 1)
            z = z + 1
        Loop
        z = z + 1
    Next
    Select Case Left(strSentence, 6)
    Case "$GPGGA"
    MyGGA.時間 = aryData(1)
    MyGGA.經度 = aryData(2)
    MyGGA.strNSIndicator = aryData(3)
    MyGGA.緯度 = aryData(4)
    MyGGA.strEWIndicator = aryData(5)
    MyGGA.strPositionFix = aryData(6)
    MyGGA.使用中的衛星顆數 = aryData(7)
    MyGGA.strIIDOP = aryData(8)
    MyGGA.高度 = aryData(9)
    MyGGA.strAltUnits = aryData(10)
    MyGGA.strGeoid = aryData(11)
    MyGGA.strSepUnits = aryData(12)
    MyGGA.strDgpsAge = aryData(13)
    MyGGA.strDgpsid = aryData(14)
    Case "$GPVTG"
    Myvtg.strCourse1 = aryData(1)
    Myvtg.strReference1 = aryData(2)
    Myvtg.strCourse2 = aryData(3)
    Myvtg.strReference2 = aryData(4)
    Myvtg.相對位移速度1 = aryData(5)
    Myvtg.strSpeedUnit1 = aryData(6)
    Myvtg.相對位移速度2 = aryData(7)
    Myvtg.strSpeedUnit2 = aryData(8)
    Case "$GPGSV"
    MyGSV.StrNoMessages = aryData(1)
    MyGSV.StrSeq = aryData(2)
    MyGSV.StrSatsinview = aryData(3)
    MyGSV.天空中衛星總數 = aryData(4)
    MyGSV.衛星仰角 = aryData(5)
    MyGSV.衛星方位角 = aryData(6)
    MyGSV.StrSNR1 = aryData(7)
    MyGSV.StrSatId2 = aryData(8)
    MyGSV.StrElevation2 = aryData(9)
    MyGSV.StrAzimuth2 = aryData(10)
    MyGSV.StrSNR2 = aryData(11)
    MyGSV.StrSatId3 = aryData(12)
    MyGSV.StrElevation3 = aryData(13)
    MyGSV.StrAzimuth3 = aryData(14)
    MyGSV.StrSNR3 = aryData(15)
    MyGSV.StrSatId4 = aryData(16)
    MyGSV.StrElevation4 = aryData(17)
    MyGSV.StrAzimuth4 = aryData(18)
    MyGSV.StrSNR4 = aryData(19)
 End Select
 End Sub
==<end>==============