Diff: main.cpp

Revision:

8:b4a6c632c809

Parent:

7:4218bb385ca4

Child:

9:b8a60ade343e

--- a/main.cpp	Sat Jul 01 05:23:43 2017 +0000
+++ b/main.cpp	Sat Jul 01 06:33:58 2017 +0000
@@ -27,19 +27,18 @@
 void gps_update(void)
 {
     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()!='$');    //wait for start of sentence
+        char nmea_sentence[82] = {0};   //Fill with NULL terminators to save doing it later
+        while (gps.getc()!='$');        //wait for start of sentence
         int nmea_index = 0;
         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
+        char nmea_char = gps.getc();        //get sentence first char from GPS
+        while (nmea_char != '*') {          //Loop building sentence and calc'ing CS until *
+             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
+                nmea_sentence[++nmea_index] = ' ';  //Pad consecutive comma with a space to make it possible to use strtok with empty values
             }
             nmea_sentence[++nmea_index] = nmea_char; //build the sentence with the next character
             if (nmea_index > 80) {
@@ -47,11 +46,13 @@
             }
             nmea_char = gps.getc();     //get next char from GPS
         }
-        //read two hex digits of CS from gps
-        char msb_gps_checksum = gps.getc();
-        char lsb_gps_checksum = gps.getc();
-
-
+        //Last character was the '*' so read the two hex digits of CS from gps
+        char hex_checksum[3] = {0};
+        hex_checksum[0] = gps.getc();
+        hex_checksum[1] = gps.getc();
+        if (checksum == (int)strtol(hex_checksum, NULL, 16) ){
+            pc.printf("Match\n\r");
+        }
 
         //     const char s[2] = ",";
         const char gprmc[7] = "$GPRMC";
@@ -64,8 +65,7 @@
        //         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);
         }