nmea_8c-source.html

国外牛人公开的ＡＶＲ代码

00131             foundpacket = NMEA_GPGGA;
00132         }
00133         <span class="keywordflow">else</span> <span class="keywordflow">if</span>(!strncmp(NmeaPacket, <span class="stringliteral">"GPVTG"</span>, 5))
00134         {
00135             <span class="comment">// process packet of this type</span>
00136             nmeaProcessGPVTG(NmeaPacket);
00137             <span class="comment">// report packet type</span>
00138             foundpacket = NMEA_GPVTG;
00139         }
00140     }
00141     <span class="keywordflow">else</span> <span class="keywordflow">if</span>(rxBuffer-&gt;<a class="code" href="structstruct__cBuffer.html#o2">datalength</a> &gt;= rxBuffer-&gt;<a class="code" href="structstruct__cBuffer.html#o1">size</a>)
00142     {
00143         <span class="comment">// if we found no packet, and the buffer is full</span>
00144         <span class="comment">// we're logjammed, flush entire buffer</span>
00145         <a class="code" href="group__buffer.html#ga7">bufferFlush</a>(rxBuffer);
00146     }
00147     <span class="keywordflow">return</span> foundpacket;
00148 }
00149 
00150 <span class="keywordtype">void</span> nmeaProcessGPGGA(u08* packet)
00151 {
00152     u08 i;
00153     <span class="keywordtype">char</span>* endptr;
00154     <span class="keywordtype">double</span> degrees, minutesfrac;
00155 
00156 <span class="preprocessor">    #ifdef NMEA_DEBUG_GGA</span>
00157 <span class="preprocessor"></span>    rprintf(<span class="stringliteral">"NMEA: "</span>);
00158     <a class="code" href="group__rprintf.html#ga2">rprintfStr</a>(packet);
00159     <a class="code" href="group__rprintf.html#ga5">rprintfCRLF</a>();
00160 <span class="preprocessor">    #endif</span>
00161 <span class="preprocessor"></span>
00162     <span class="comment">// start parsing just after "GPGGA,"</span>
00163     i = 6;
00164     <span class="comment">// attempt to reject empty packets right away</span>
00165     <span class="keywordflow">if</span>(packet[i]==<span class="charliteral">','</span> &amp;&amp; packet[i+1]==<span class="charliteral">','</span>)
00166         <span class="keywordflow">return</span>;
00167 
00168     <span class="comment">// get UTC time [hhmmss.sss]</span>
00169     GpsInfo.PosLLA.TimeOfFix.f = strtod(&amp;packet[i], &amp;endptr);
00170     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: latitude</span>
00171     
00172     <span class="comment">// get latitude [ddmm.mmmmm]</span>
00173     GpsInfo.PosLLA.lat.f = strtod(&amp;packet[i], &amp;endptr);
00174     <span class="comment">// convert to pure degrees [dd.dddd] format</span>
00175     minutesfrac = modf(GpsInfo.PosLLA.lat.f/100, &amp;degrees);
00176     GpsInfo.PosLLA.lat.f = degrees + (minutesfrac*100)/60;
00177     <span class="comment">// convert to radians</span>
00178     GpsInfo.PosLLA.lat.f *= (M_PI/180);
00179     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: N/S indicator</span>
00180     
00181     <span class="comment">// correct latitute for N/S</span>
00182     <span class="keywordflow">if</span>(packet[i] == <span class="charliteral">'S'</span>) GpsInfo.PosLLA.lat.f = -GpsInfo.PosLLA.lat.f;
00183     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: longitude</span>
00184     
00185     <span class="comment">// get longitude [ddmm.mmmmm]</span>
00186     GpsInfo.PosLLA.lon.f = strtod(&amp;packet[i], &amp;endptr);
00187     <span class="comment">// convert to pure degrees [dd.dddd] format</span>
00188     minutesfrac = modf(GpsInfo.PosLLA.lon.f/100, &amp;degrees);
00189     GpsInfo.PosLLA.lon.f = degrees + (minutesfrac*100)/60;
00190     <span class="comment">// convert to radians</span>
00191     GpsInfo.PosLLA.lon.f *= (M_PI/180);
00192     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: E/W indicator</span>
00193 
00194     <span class="comment">// correct latitute for E/W</span>
00195     <span class="keywordflow">if</span>(packet[i] == <span class="charliteral">'W'</span>) GpsInfo.PosLLA.lon.f = -GpsInfo.PosLLA.lon.f;
00196     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: position fix status</span>
00197 
00198     <span class="comment">// position fix status</span>
00199     <span class="comment">// 0 = Invalid, 1 = Valid SPS, 2 = Valid DGPS, 3 = Valid PPS</span>
00200     <span class="comment">// check for good position fix</span>
00201     <span class="keywordflow">if</span>( (packet[i] != <span class="charliteral">'0'</span>) &amp;&amp; (packet[i] != <span class="charliteral">','</span>) )
00202         GpsInfo.PosLLA.updates++;
00203     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: satellites used</span>
00204     
00205     <span class="comment">// get number of satellites used in GPS solution</span>
00206     GpsInfo.numSVs = atoi(&amp;packet[i]);
00207     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: HDOP (horizontal dilution of precision)</span>
00208     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: altitude</span>
00209     
00210     <span class="comment">// get altitude (in meters)</span>
00211     GpsInfo.PosLLA.alt.f = strtod(&amp;packet[i], &amp;endptr);
00212 
00213     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: altitude units, always 'M'</span>
00214     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: geoid seperation</span>
00215     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: seperation units</span>
00216     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: DGPS age</span>
00217     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: DGPS station ID</span>
00218     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">'*'</span>);              <span class="comment">// next field: checksum</span>
00219 }
00220 
00221 <span class="keywordtype">void</span> nmeaProcessGPVTG(u08* packet)
00222 {
00223     u08 i;
00224     <span class="keywordtype">char</span>* endptr;
00225 
00226 <span class="preprocessor">    #ifdef NMEA_DEBUG_VTG</span>
00227 <span class="preprocessor"></span>    rprintf(<span class="stringliteral">"NMEA: "</span>);
00228     <a class="code" href="group__rprintf.html#ga2">rprintfStr</a>(packet);
00229     <a class="code" href="group__rprintf.html#ga5">rprintfCRLF</a>();
00230 <span class="preprocessor">    #endif</span>
00231 <span class="preprocessor"></span>
00232     <span class="comment">// start parsing just after "GPVTG,"</span>
00233     i = 6;
00234     <span class="comment">// attempt to reject empty packets right away</span>
00235     <span class="keywordflow">if</span>(packet[i]==<span class="charliteral">','</span> &amp;&amp; packet[i+1]==<span class="charliteral">','</span>)
00236         <span class="keywordflow">return</span>;
00237 
00238     <span class="comment">// get course (true north ref) in degrees [ddd.dd]</span>
00239     GpsInfo.VelHS.heading.f = strtod(&amp;packet[i], &amp;endptr);
00240     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: 'T'</span>
00241     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: course (magnetic north)</span>
00242 
00243     <span class="comment">// get course (magnetic north ref) in degrees [ddd.dd]</span>
00244     <span class="comment">//GpsInfo.VelHS.heading.f = strtod(&amp;packet[i], &amp;endptr);</span>
00245     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: 'M'</span>
00246     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: speed (knots)</span>
00247 
00248     <span class="comment">// get speed in knots</span>
00249     <span class="comment">//GpsInfo.VelHS.speed.f = strtod(&amp;packet[i], &amp;endptr);</span>
00250     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: 'N'</span>
00251     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: speed (km/h)</span>
00252 
00253     <span class="comment">// get speed in km/h</span>
00254     GpsInfo.VelHS.speed.f = strtod(&amp;packet[i], &amp;endptr);
00255     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: 'K'</span>
00256     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">'*'</span>);              <span class="comment">// next field: checksum</span>
00257 
00258     GpsInfo.VelHS.updates++;
00259 }
00260 
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