Revision 0:9c001c4e7bf4, committed 2014-02-16

Comitter:

stearnsc

Date:

Sun Feb 16 21:26:54 2014 +0000

Child:

1:aef1562834b4

Child:

2:f480097b329d

Commit message:

cs: First pass of gps parsing

Changed in this revision

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Sun Feb 16 21:26:54 2014 +0000
@@ -0,0 +1,160 @@
+#include "mbed.h"
+#include <string>
+#include <sstream>
+
+Serial pc(USBTX,USBRX);
+Serial xbee(p9,p10);//tx, rx
+Serial gps(p28,p27);
+
+typedef struct {
+    int latitude;  //in .0001 minutes
+    int longitude; //in .0001 minutes
+    int altitude;  //in decimeters
+    int time;      //in milliseconds
+} GpsData;
+
+GpsData gpsData;
+GpsData otherGps;
+
+void readSerial(Serial &s, char str[], int size){
+    for (int i = 0; i < size; i++){
+        str[i] = s.getc();   
+    }
+}
+
+//sends: "$<command>*<checksum>\r\l"
+void sendGpsCommand(string command){
+    uint8_t checksum = 0;
+    pc.printf("Sending command to gps: ");
+    gps.putc('$');
+    pc.putc('$');
+    char c;
+    for (int i = 0; i < command.length(); i++){
+        c = command[i];
+        checksum ^= c;
+        gps.putc(c);
+        pc.putc(c);
+    }
+    gps.putc('*');
+    pc.putc('*');
+    string checkSumString;
+    while (checksum > 0){
+        uint8_t checksumChar = checksum & 0x0F;
+        if (checksumChar >= 10){
+            checksumChar -= 10;
+            checksumChar += 'A'; 
+        } else {
+            checksumChar += '0';   
+        }
+        checkSumString.push_back((char) checksumChar);
+        checksum = checksum >> 4;    
+    }
+
+    for (int i = checkSumString.length() - 1; i >= 0; i--){
+        gps.putc(checkSumString[i]);
+        pc.putc(checkSumString[i]);   
+    } 
+    gps.putc('\r');
+    pc.putc('\r');
+    gps.putc('\n');
+    pc.putc('\n');
+}
+
+long parseDec(string s){
+    int mult = 1;
+    int result = 0;
+    for (int i = s.length() - 1; i >=0; i--){
+        if (s[i] != '.'){
+            result += (s[i] - '0') * mult;
+            mult *= 10;
+        }
+    }
+    return result;
+}
+
+//cs: little endian parsing
+int nextInt(char *data, int i){
+   i |= data[i];
+   i |= (data[i + 1] << 8);
+   i |= (data[i + 2] << 16);
+   i |= (data[i + 3] << 24);
+   return i;
+}
+
+void handleXbeeGps(){
+    static bool reading = false;
+    static char packet[16];
+    static int i = 0;
+    
+    char c = xbee.getc();
+    if (reading){
+        packet[i] = c;
+        i++;
+        if (i == 16){
+            i = 0;
+            otherGps.latitude = nextInt(packet, 0);
+            otherGps.longitude = nextInt(packet, 4);
+            otherGps.altitude = nextInt(packet, 8);
+            otherGps.time = nextInt(packet, 12);
+            
+            pc.printf("His GPS data: Lat: %d, Lon: %d, Alt: %d, Time:%d\r\n",
+                otherGps.latitude, otherGps.longitude, otherGps.altitude, otherGps.time
+            );
+            reading = false;
+        }
+    } else if (c == 'X'){
+        reading = true;    
+    }
+}
+
+void handleGpsData(){
+     static bool reading = false;
+     static stringstream line;
+     
+     char c = gps.getc();
+     
+     if (reading){
+        if (c == '*'){ //sentence buffer complete; we're ignoring the checksum
+            string field;
+            std::getline(line, field, ','); //GPGGA
+            std::getline(line, field, ','); //time
+            gpsData.time = parseDec(field);
+            std::getline(line, field, ','); //latitude
+            gpsData.latitude = parseDec(field);
+            std::getline(line, field, ','); //N or S
+            std::getline(line, field, ','); //longitude
+            gpsData.longitude = parseDec(field);
+            std::getline(line, field, ','); //E or W
+            std::getline(line, field, ','); //skip  
+            std::getline(line, field, ','); //skip
+            std::getline(line, field, ','); //skip
+            std::getline(line, field, ','); //altitude
+            gpsData.altitude = parseDec(field);
+            
+            //update whatever needs updating when gps updates
+            pc.printf("My GPS data: Lat: %d, Lon: %d, Alt: %d, Time:%d\r\n",
+                gpsData.latitude, gpsData.longitude, gpsData.altitude, gpsData.time
+            );
+            
+            line.str(string(""));
+            reading = false;
+            
+        } else {
+            line.put(c);    
+        }
+        
+     } else if (c == '$') {
+        reading = true;
+     }
+}
+
+int main(){
+    gps.baud(57600);
+    xbee.baud(9600);
+    pc.baud(57600);
+    
+//    sendGpsCommand("PMTK301,1");
+//    while(true){pc.putc(gps.getc());}
+    gps.attach(&handleGpsData, Serial::RxIrq);
+//    xbee.attach(&handleXbeeGps, Serial::RxIrq);
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.bld	Sun Feb 16 21:26:54 2014 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/mbed_official/code/mbed/builds/a9913a65894f
\ No newline at end of file