Diff: main.cpp

Revision:

7:4218bb385ca4

Parent:

6:af25f19eb4e6

Child:

8:b4a6c632c809

--- a/main.cpp	Sat Jul 01 02:02:38 2017 +0000
+++ b/main.cpp	Sat Jul 01 05:23:43 2017 +0000
@@ -26,35 +26,33 @@
 
 void gps_update(void)
 {
-    char nmea_descriptor[5] = {0};
     gps_power(on);
     while (1) {
+        int checksum = 0;
         char nmea_sentence[82] = {0}; //Fill with NULL terminators
-        gps.format(8,Serial::None,1);
-        while (gps.getc()!='$');   //wait for start of sentence
+        //gps.format(8,Serial::None,1);
+        while (gps.getc()!='$');    //wait for start of sentence
         int nmea_index = 0;
-        nmea_sentence[nmea_index] = '$';
-        while (nmea_sentence[nmea_index++] != '\n') {
-            char nmea_char = gps.getc();
-            if ((nmea_sentence[nmea_index-1] == ',')&&(nmea_char == ',')) {
-                nmea_sentence[nmea_index++] = ' ';  //Pad consecutive comma with a space
+        nmea_sentence[nmea_index] = '$';    //Manually insert the '$' because we don't want it included in the checksum loop
+        char nmea_char = gps.getc();             //get sentence first char from GPS
+        while (nmea_char != '*') {
+ //           pc.putc(nmea_char);
+            checksum ^= nmea_char;        //Calc checksum as we read sentence
+            if ((nmea_sentence[nmea_index] == ',')&&(nmea_char == ',')) {
+                nmea_sentence[++nmea_index] = ' ';  //Pad consecutive comma with a space
             }
-            if (nmea_char == '*'){
-                nmea_sentence[nmea_index++] = ',';  //inserting a comma before CS makes handling easier
-            }    
-            nmea_sentence[nmea_index] = nmea_char; //build the sentence
+            nmea_sentence[++nmea_index] = nmea_char; //build the sentence with the next character
             if (nmea_index > 80) {
                 nmea_index=80;          //Don't overflow buffer
             }
+            nmea_char = gps.getc();     //get next char from GPS
         }
-        // Checksum
-        bool checksum_valid = FALSE;
-        int checksum = 0;
-        int i = 1;  //After the '$'
-        while (nmea_sentence[i++] != '*'){
-            checksum ^= nmea_sentence[i];
-        }
-        pc.printf( "Checksum: %i\n\r", checksum );
+        //read two hex digits of CS from gps
+        char msb_gps_checksum = gps.getc();
+        char lsb_gps_checksum = gps.getc();
+
+
+
         //     const char s[2] = ",";
         const char gprmc[7] = "$GPRMC";
         char *token;
@@ -63,8 +61,12 @@
             pc.printf( " %s\n\r", token );
             while (token != NULL) {
                 token = strtok(NULL, ",");
-                pc.printf( " %s\n\r", token );
+       //         pc.printf( " %s\n\r", token );
             }
+     //               pc.printf("GPS CS:");
+        pc.putc(msb_gps_checksum);
+        pc.putc(lsb_gps_checksum);
+        pc.printf("%d \n\r",checksum);
         }
 
         while (gps.readable()) {
@@ -88,15 +90,16 @@
     wait(2);
     while (1) {
         gps_update();
+
+
     }
 }
 
 
-  
-  
-      
-      
+
+
+
 
-      
+
 
-      
\ No newline at end of file
+