GPS: using fixed-point 32-bit value for latitude and longitude

openrtx/include/core/gps.h

@@ -48,8 +48,8 @@ typedef struct
     uint8_t    satellites_in_view;   // Satellites in view
     gpssat_t   satellites[12];       // Details about satellites in view
     uint32_t   active_sats;          // Bitmap representing which sats are part of the fix
-    float      latitude;             // Latitude coordinates
-    float      longitude;            // Longitude coordinates
+    int32_t    latitude;             // Latitude coordinates
+    int32_t    longitude;            // Longitude coordinates
     float      altitude;             // Antenna altitude above mean sea level (geoid) in m
     float      speed;                // Ground speed in km/h
     float      tmg_mag;              // Course over ground, degrees, magnetic

openrtx/src/core/gps.c

@@ -90,8 +90,8 @@ void gps_task()
             struct minmea_sentence_rmc frame;
             if (minmea_parse_rmc(&frame, sentence))
             {
-                gps_data.latitude = minmea_tocoord(&frame.latitude);
-                gps_data.longitude = minmea_tocoord(&frame.longitude);
+                gps_data.latitude = minmea_tofixedpoint(&frame.latitude);
+                gps_data.longitude = minmea_tofixedpoint(&frame.longitude);
                 gps_data.timestamp.hour = frame.time.hours;
                 gps_data.timestamp.minute = frame.time.minutes;
                 gps_data.timestamp.second = frame.time.seconds;

openrtx/src/core/voicePromptUtils.c

@@ -30,6 +30,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <utils.h>
+#include <inttypes.h>
 #include <ui/ui_default.h>
 #include <beeps.h>
 #include "interfaces/cps_io.h"
@@ -689,20 +690,26 @@ void vp_announceGPSInfo(vpGPSInfoFlags_t gpsInfoFlags)
 
     if ((gpsInfoFlags & vpGPSLatitude) != 0)
     {
-        // lat/long
-        sniprintf(buffer, 16, "%8.6f", state.gps_data.latitude);
+        // Convert from signed longitude, to unsigned + direction
+        int32_t latitude        = abs(state.gps_data.latitude);
+        uint8_t latitude_int    = latitude / 1000000;
+        int32_t latitude_dec    = latitude % 1000000;
+        voicePrompt_t direction = (state.gps_data.latitude < 0) ? PROMPT_SOUTH : PROMPT_NORTH;
+        sniprintf(buffer, 16, "%d.%06"PRId32, latitude_int, latitude_dec);
         stripTrailingZeroes(buffer);
         vp_queuePrompt(PROMPT_LATITUDE);
         vp_queueString(buffer, vpAnnounceCommonSymbols);
-        vp_queuePrompt(PROMPT_NORTH);
+        vp_queuePrompt(direction);
     }
 
     if ((gpsInfoFlags & vpGPSLongitude) != 0)
     {
-        float longitude         = state.gps_data.longitude;
-        voicePrompt_t direction = (longitude < 0) ? PROMPT_WEST : PROMPT_EAST;
-        longitude               = (longitude < 0) ? -longitude : longitude;
-        sniprintf(buffer, 16, "%8.6f", longitude);
+        // Convert from signed longitude, to unsigned + direction
+        int32_t longitude       = abs(state.gps_data.longitude);
+        uint8_t longitude_int   = longitude / 1000000;
+        int32_t longitude_dec   = longitude % 1000000;
+        voicePrompt_t direction = (state.gps_data.longitude < 0) ? PROMPT_WEST : PROMPT_EAST;
+        sniprintf(buffer, 16, "%d.%06"PRId32, longitude_int, longitude_dec);
         stripTrailingZeroes(buffer);
 
         vp_queuePrompt(PROMPT_LONGITUDE);

openrtx/src/ui/default/ui_menu.c

@@ -682,20 +682,30 @@ void _ui_drawMenuGPS()
         }
         gfx_print(layout.line1_pos, layout.top_font, TEXT_ALIGN_LEFT,
                   color_white, fix_buf);
+
+        // Convert from signed longitude, to unsigned + direction
+        int32_t latitude     = abs(last_state.gps_data.latitude);
+        uint8_t latitude_int = latitude / 1000000;
+        int32_t latitude_dec = latitude % 1000000;
+        char *direction_lat  = (last_state.gps_data.latitude < 0) ? "S     " : "N     ";
+
         gfx_print(layout.line1_pos, layout.top_font, TEXT_ALIGN_CENTER,
-                  color_white, "N     ");
+                  color_white, direction_lat);
         gfx_print(layout.line1_pos, layout.top_font, TEXT_ALIGN_RIGHT,
-                  color_white, "%8.6f", last_state.gps_data.latitude);
+                  color_white, "%d.%.6d", latitude_int, latitude_dec);
         gfx_print(layout.line2_pos, layout.top_font, TEXT_ALIGN_LEFT,
                   color_white, type_buf);
+
         // Convert from signed longitude, to unsigned + direction
-        float longitude = last_state.gps_data.longitude;
-        char *direction = (longitude < 0) ? "W     " : "E     ";
-        longitude = (longitude < 0) ? -longitude : longitude;
+        int32_t longitude     = abs(last_state.gps_data.longitude);
+        uint8_t longitude_int = longitude / 1000000;
+        int32_t longitude_dec = longitude % 1000000;
+        char *direction_lon   = (last_state.gps_data.longitude < 0) ? "W     " : "E     ";
+
         gfx_print(layout.line2_pos, layout.top_font, TEXT_ALIGN_CENTER,
-                  color_white, direction);
+                  color_white, direction_lon);
         gfx_print(layout.line2_pos, layout.top_font, TEXT_ALIGN_RIGHT,
-                  color_white, "%8.6f", longitude);
+                  color_white, "%d.%.6d", longitude_int, longitude_dec);
         gfx_print(layout.bottom_pos, layout.bottom_font, TEXT_ALIGN_CENTER,
                   color_white, "S %4.1fkm/h  A %4.1fm",
                   last_state.gps_data.speed,