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avr cpu 库源代码 对avr单片机编程很有帮助

00130             foundpacket = NMEA_GPGGA;
00131         }
00132         <span class="keywordflow">else</span> <span class="keywordflow">if</span>(!strncmp(NmeaPacket, <span class="stringliteral">"GPVTG"</span>, 5))
00133         {
00134             <span class="comment">// process packet of this type</span>
00135             nmeaProcessGPVTG(NmeaPacket);
00136             <span class="comment">// report packet type</span>
00137             foundpacket = NMEA_GPVTG;
00138         }
00139     }
00140     <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>)
00141     {
00142         <span class="comment">// if we found no packet, and the buffer is full</span>
00143         <span class="comment">// we're logjammed, flush entire buffer</span>
00144         <a class="code" href="group__buffer.html#ga7">bufferFlush</a>(rxBuffer);
00145     }
00146     <span class="keywordflow">return</span> foundpacket;
00147 }
00148 
00149 <span class="keywordtype">void</span> nmeaProcessGPGGA(u08* packet)
00150 {
00151     u08 i;
00152     <span class="keywordtype">char</span>* endptr;
00153     <span class="keywordtype">double</span> degrees, minutesfrac;
00154 
00155 <span class="preprocessor">    #ifdef NMEA_DEBUG_GGA</span>
00156 <span class="preprocessor"></span>    rprintf(<span class="stringliteral">"NMEA: "</span>);
00157     <a class="code" href="group__rprintf.html#ga2">rprintfStr</a>(packet);
00158     <a class="code" href="group__rprintf.html#ga5">rprintfCRLF</a>();
00159 <span class="preprocessor">    #endif</span>
00160 <span class="preprocessor"></span>
00161     <span class="comment">// start parsing just after "GPGGA,"</span>
00162     i = 6;
00163     <span class="comment">// attempt to reject empty packets right away</span>
00164     <span class="keywordflow">if</span>(packet[i]==<span class="charliteral">','</span> &amp;&amp; packet[i+1]==<span class="charliteral">','</span>)
00165         <span class="keywordflow">return</span>;
00166 
00167     <span class="comment">// get UTC time [hhmmss.sss]</span>
00168     GpsInfo.PosLLA.TimeOfFix.f = strtod(&amp;packet[i], &amp;endptr);
00169     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: latitude</span>
00170     
00171     <span class="comment">// get latitude [ddmm.mmmmm]</span>
00172     GpsInfo.PosLLA.lat.f = strtod(&amp;packet[i], &amp;endptr);
00173     <span class="comment">// convert to pure degrees [dd.dddd] format</span>
00174     minutesfrac = modf(GpsInfo.PosLLA.lat.f/100, &amp;degrees);
00175     GpsInfo.PosLLA.lat.f = degrees + (minutesfrac*100)/60;
00176     <span class="comment">// convert to radians</span>
00177     GpsInfo.PosLLA.lat.f *= (M_PI/180);
00178     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: N/S indicator</span>
00179     
00180     <span class="comment">// correct latitute for N/S</span>
00181     <span class="keywordflow">if</span>(packet[i] == <span class="charliteral">'S'</span>) GpsInfo.PosLLA.lat.f = -GpsInfo.PosLLA.lat.f;
00182     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: longitude</span>
00183     
00184     <span class="comment">// get longitude [ddmm.mmmmm]</span>
00185     GpsInfo.PosLLA.lon.f = strtod(&amp;packet[i], &amp;endptr);
00186     <span class="comment">// convert to pure degrees [dd.dddd] format</span>
00187     minutesfrac = modf(GpsInfo.PosLLA.lon.f/100, &amp;degrees);
00188     GpsInfo.PosLLA.lon.f = degrees + (minutesfrac*100)/60;
00189     <span class="comment">// convert to radians</span>
00190     GpsInfo.PosLLA.lon.f *= (M_PI/180);
00191     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: E/W indicator</span>
00192 
00193     <span class="comment">// correct latitute for E/W</span>
00194     <span class="keywordflow">if</span>(packet[i] == <span class="charliteral">'W'</span>) GpsInfo.PosLLA.lon.f = -GpsInfo.PosLLA.lon.f;
00195     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: position fix status</span>
00196 
00197     <span class="comment">// position fix status</span>
00198     <span class="comment">// 0 = Invalid, 1 = Valid SPS, 2 = Valid DGPS, 3 = Valid PPS</span>
00199     <span class="comment">// check for good position fix</span>
00200     <span class="keywordflow">if</span>( (packet[i] != <span class="charliteral">'0'</span>) &amp;&amp; (packet[i] != <span class="charliteral">','</span>) )
00201         GpsInfo.PosLLA.updates++;
00202     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: satellites used</span>
00203     
00204     <span class="comment">// get number of satellites used in GPS solution</span>
00205     GpsInfo.numSVs = atoi(&amp;packet[i]);
00206     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: HDOP (horizontal dilution of precision)</span>
00207     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: altitude</span>
00208     
00209     <span class="comment">// get altitude (in meters)</span>
00210     GpsInfo.PosLLA.alt.f = strtod(&amp;packet[i], &amp;endptr);
00211 
00212     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: altitude units, always 'M'</span>
00213     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: geoid seperation</span>
00214     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: seperation units</span>
00215     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: DGPS age</span>
00216     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: DGPS station ID</span>
00217     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">'*'</span>);              <span class="comment">// next field: checksum</span>
00218 }
00219 
00220 <span class="keywordtype">void</span> nmeaProcessGPVTG(u08* packet)
00221 {
00222     u08 i;
00223     <span class="keywordtype">char</span>* endptr;
00224 
00225 <span class="preprocessor">    #ifdef NMEA_DEBUG_VTG</span>
00226 <span class="preprocessor"></span>    rprintf(<span class="stringliteral">"NMEA: "</span>);
00227     <a class="code" href="group__rprintf.html#ga2">rprintfStr</a>(packet);
00228     <a class="code" href="group__rprintf.html#ga5">rprintfCRLF</a>();
00229 <span class="preprocessor">    #endif</span>
00230 <span class="preprocessor"></span>
00231     <span class="comment">// start parsing just after "GPVTG,"</span>
00232     i = 6;
00233     <span class="comment">// attempt to reject empty packets right away</span>
00234     <span class="keywordflow">if</span>(packet[i]==<span class="charliteral">','</span> &amp;&amp; packet[i+1]==<span class="charliteral">','</span>)
00235         <span class="keywordflow">return</span>;
00236 
00237     <span class="comment">// get course (true north ref) in degrees [ddd.dd]</span>
00238     GpsInfo.VelHS.heading.f = strtod(&amp;packet[i], &amp;endptr);
00239     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: 'T'</span>
00240     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: course (magnetic north)</span>
00241 
00242     <span class="comment">// get course (magnetic north ref) in degrees [ddd.dd]</span>
00243     <span class="comment">//GpsInfo.VelHS.heading.f = strtod(&amp;packet[i], &amp;endptr);</span>
00244     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: 'M'</span>
00245     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: speed (knots)</span>
00246 
00247     <span class="comment">// get speed in knots</span>
00248     <span class="comment">//GpsInfo.VelHS.speed.f = strtod(&amp;packet[i], &amp;endptr);</span>
00249     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: 'N'</span>
00250     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: speed (km/h)</span>
00251 
00252     <span class="comment">// get speed in km/h</span>
00253     GpsInfo.VelHS.speed.f = strtod(&amp;packet[i], &amp;endptr);
00254     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">','</span>);              <span class="comment">// next field: 'K'</span>
00255     <span class="keywordflow">while</span>(packet[i++] != <span class="charliteral">'*'</span>);              <span class="comment">// next field: checksum</span>
00256 
00257     GpsInfo.VelHS.updates++;
00258 }
00259 
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