private void PublishFix(GPSFix fix, NMEASentenceType fixSource)
{
if (fixSource == fixTriggerSentence)
{
if (haveGGA && haveRMC)
{
// Output a combined fix if the partial fix is valid.
if ((partialFix != null) && (partialFix.UTCFixTime == fix.UTCFixTime) &&
(fixSource != partialFixSentenceType))
{
GPSFix fixRMC = fixSource == NMEASentenceType.RMC ? fix : partialFix;
GPSFix fixGGA = fixSource == NMEASentenceType.GGA ? fix : partialFix;
m_MostRecentGPSFix = fixGGA;
m_MostRecentGPSFix.HeadingRadians = fixRMC.HeadingRadians;
m_MostRecentGPSFix.SpeedEast = fixRMC.SpeedEast;
m_MostRecentGPSFix.SpeedNorth = fixRMC.SpeedNorth;
// Still need to calculate vertical speed. Sigh.
CalculateSpeedAndHeading(m_MostRecentGPSFix, true);
}
partialFix = null;
partialFixSentenceType = NMEASentenceType.Unknown;
}
else if (fixSource == NMEASentenceType.GGA)
{
// Don't have speed information, so calculate it.
m_MostRecentGPSFix = fix;
CalculateSpeedAndHeading(m_MostRecentGPSFix, false);
}
else if (fixSource == NMEASentenceType.RMC)
{
// Publish the fix as is.
m_MostRecentGPSFix = fix;
}
}
else
{
// Save the fix until we hit the trigger sentence.
partialFix = fix;
partialFixSentenceType = fixSource;
}
}
public void Reset()
{
readBuffer = "";
partialFix = null;
partialFixSentenceType = NMEASentenceType.Unknown;
haveGGA = false;
haveRMC = false;
lastGGATimestamp = new DateTime(0);
lastRMCTimestamp = new DateTime(0);
fixTriggerSentence = NMEASentenceType.Unknown;
savedFix = null;
m_MostRecentGPSFix = null;
gsaData = null;
partialSatelliteVehicles = null;
partialSatelliteVehicleIndex = 0;
m_MostRecentSatelliteVehicles = null;
lastGSVMessageNumber = 0;
}
private void PublishFix(GPSFix fix, NMEASentenceType fixSource)
{
if (fixSource == fixTriggerSentence)
{
if (haveGGA && haveRMC)
{
// Output a combined fix if the partial fix is valid.
if ((partialFix != null) && (partialFix.UTCFixTime == fix.UTCFixTime) &&
(fixSource != partialFixSentenceType))
{
GPSFix fixRMC = fixSource == NMEASentenceType.RMC ? fix : partialFix;
GPSFix fixGGA = fixSource == NMEASentenceType.GGA ? fix : partialFix;
m_MostRecentGPSFix = fixGGA;
m_MostRecentGPSFix.HeadingRadians = fixRMC.HeadingRadians;
m_MostRecentGPSFix.SpeedEast = fixRMC.SpeedEast;
m_MostRecentGPSFix.SpeedNorth = fixRMC.SpeedNorth;
// Still need to calculate vertical speed. Sigh.
CalculateSpeedAndHeading(m_MostRecentGPSFix, true);
}
partialFix = null;
partialFixSentenceType = NMEASentenceType.Unknown;
}
else if (fixSource == NMEASentenceType.GGA)
{
// Don't have speed information, so calculate it.
m_MostRecentGPSFix = fix;
CalculateSpeedAndHeading(m_MostRecentGPSFix, false);
}
else if (fixSource == NMEASentenceType.RMC)
{
// Publish the fix as is.
m_MostRecentGPSFix = fix;
}
}
else
{
// Save the fix until we hit the trigger sentence.
partialFix = fix;
partialFixSentenceType = fixSource;
}
}
public void ProcessReceivedData(byte[] rawData)
{
const string hexChars = "0123456789ABCDEF";
// Add the data to the read buffer.
Encoding ascii = Encoding.ASCII;
readBuffer += ascii.GetString(rawData, 0, rawData.Length).ToUpper();
// Process received lines. The last entry in the array (which may be an empty string)
// is always an incomplete line as it wasn't followed by a "\n". Therefore it needs
// to go back into the read buffer.
string[] lines = readBuffer.Split(new char[] {'\n'});
readBuffer = lines[lines.Length - 1];
int i;
for (i = 0; i < lines.Length - 1; i++)
{
// Split the checksum off from the line. If we don't find one, ignore the line.
int hi, lo;
string[] elements = lines[i].Trim().Split(new char[] {'*'});
if ((elements.Length == 2) && elements[0].StartsWith("$") && (elements[1].Length == 2) &&
((hi = hexChars.IndexOf(elements[1][0])) >= 0) &&
((lo = hexChars.IndexOf(elements[1][1])) >= 0))
{
// Verify the checksum.
byte checksum = (byte)(hi << 4 | lo);
byte c = 0;
int j;
for (j = 1; j < elements[0].Length; j++)
c ^= (byte)elements[0][j];
if (c == checksum)
{
// Valid NMEA sentence. Split it into its components and process it after
// removing the leading '$'. There will always be at least one part, even
// if it is empty.
string[] parts = elements[0].Remove(0, 1).Split(new char[] {','});
// Decide whether to use GGA or RMC sentences, or both.
if (fixTriggerSentence == NMEASentenceType.Unknown)
{
if (parts[0] == "GPGGA")
{
haveGGA = true;
if (! haveRMC && (lastGGATimestamp.Ticks != 0))
{
// This is the second GGA fix we have seen without an intervening RMC fix.
// Assume no RMC packets.
fixTriggerSentence = NMEASentenceType.GGA;
}
lastGGATimestamp = ParseNMEATimestamp(parts.Length > 0 ? parts[1] : "");
if (haveRMC)
{
if (lastRMCTimestamp == lastGGATimestamp)
fixTriggerSentence = NMEASentenceType.GGA;
else
fixTriggerSentence = NMEASentenceType.RMC;
}
}
else if (parts[0] == "GPRMC")
{
haveRMC = true;
if (! haveGGA && (lastRMCTimestamp.Ticks != 0))
{
// This is the second RMC fix we have seen without an intervening GGA fix.
// Assume no GGA packets.
fixTriggerSentence = NMEASentenceType.RMC;
}
lastRMCTimestamp = ParseNMEATimestamp(parts.Length > 0 ? parts[1] : "");
if (haveGGA)
{
if (lastGGATimestamp == lastRMCTimestamp)
fixTriggerSentence = NMEASentenceType.RMC;
else
fixTriggerSentence = NMEASentenceType.GGA;
}
}
}
// Process specific sentence types.
switch (parts[0])
{
case "GPGGA":
ProcessGGA(parts);
break;
case "GPGSA":
ProcessGSA(parts);
break;
case "GPGSV":
ProcessGSV(parts);
break;
case "GPRMC":
ProcessRMC(parts);
break;
}
}
}
}
}
public void Reset()
{
readBuffer = "";
partialFix = null;
partialFixSentenceType = NMEASentenceType.Unknown;
haveGGA = false;
haveRMC = false;
lastGGATimestamp = new DateTime(0);
lastRMCTimestamp = new DateTime(0);
fixTriggerSentence = NMEASentenceType.Unknown;
savedFix = null;
m_MostRecentGPSFix = null;
gsaData = null;
partialSatelliteVehicles = null;
partialSatelliteVehicleIndex = 0;
m_MostRecentSatelliteVehicles = null;
lastGSVMessageNumber = 0;
}
public void ProcessReceivedData(byte[] rawData)
{
const string hexChars = "0123456789ABCDEF";
// Add the data to the read buffer.
Encoding ascii = Encoding.ASCII;
readBuffer += ascii.GetString(rawData, 0, rawData.Length).ToUpper();
// Process received lines. The last entry in the array (which may be an empty string)
// is always an incomplete line as it wasn't followed by a "\n". Therefore it needs
// to go back into the read buffer.
string[] lines = readBuffer.Split(new char[] { '\n' });
readBuffer = lines[lines.Length - 1];
int i;
for (i = 0; i < lines.Length - 1; i++)
{
// Split the checksum off from the line. If we don't find one, ignore the line.
int hi, lo;
string[] elements = lines[i].Trim().Split(new char[] { '*' });
if ((elements.Length == 2) && elements[0].StartsWith("$") && (elements[1].Length == 2) &&
((hi = hexChars.IndexOf(elements[1][0])) >= 0) &&
((lo = hexChars.IndexOf(elements[1][1])) >= 0))
{
// Verify the checksum.
byte checksum = (byte)(hi << 4 | lo);
byte c = 0;
int j;
for (j = 1; j < elements[0].Length; j++)
{
c ^= (byte)elements[0][j];
}
if (c == checksum)
{
// Valid NMEA sentence. Split it into its components and process it after
// removing the leading '$'. There will always be at least one part, even
// if it is empty.
string[] parts = elements[0].Remove(0, 1).Split(new char[] { ',' });
// Decide whether to use GGA or RMC sentences, or both.
if (fixTriggerSentence == NMEASentenceType.Unknown)
{
if (parts[0] == "GPGGA")
{
haveGGA = true;
if (!haveRMC && (lastGGATimestamp.Ticks != 0))
{
// This is the second GGA fix we have seen without an intervening RMC fix.
// Assume no RMC packets.
fixTriggerSentence = NMEASentenceType.GGA;
}
lastGGATimestamp = ParseNMEATimestamp(parts.Length > 0 ? parts[1] : "");
if (haveRMC)
{
if (lastRMCTimestamp == lastGGATimestamp)
{
fixTriggerSentence = NMEASentenceType.GGA;
}
else
{
fixTriggerSentence = NMEASentenceType.RMC;
}
}
}
else if (parts[0] == "GPRMC")
{
haveRMC = true;
if (!haveGGA && (lastRMCTimestamp.Ticks != 0))
{
// This is the second RMC fix we have seen without an intervening GGA fix.
// Assume no GGA packets.
fixTriggerSentence = NMEASentenceType.RMC;
}
lastRMCTimestamp = ParseNMEATimestamp(parts.Length > 0 ? parts[1] : "");
if (haveGGA)
{
if (lastGGATimestamp == lastRMCTimestamp)
{
fixTriggerSentence = NMEASentenceType.RMC;
}
else
{
fixTriggerSentence = NMEASentenceType.GGA;
}
}
}
}
// Process specific sentence types.
switch (parts[0])
{
case "GPGGA":
ProcessGGA(parts);
break;
case "GPGSA":
ProcessGSA(parts);
break;
case "GPGSV":
ProcessGSV(parts);
break;
case "GPRMC":
ProcessRMC(parts);
break;
}
}
}
}
}
