287 lines
7.6 KiB
C
287 lines
7.6 KiB
C
#include "GPS.h"
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Serial *serial;
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bool gps_installed = false;
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bool gps_power = true;
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uint8_t nmea_read_length = 0;
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char nmea_input_buf[NMEA_MAX_LENGTH];
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char nmea_parse_buf[NMEA_MAX_LENGTH];
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bool gps_detect(void) {
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GPS_DDR &= ~_BV(GPS_EN_PIN);
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return (GPS_INPUT & _BV(GPS_EN_PIN));
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}
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void gps_powerup(void) {
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GPS_PORT |= _BV(GPS_EN_PIN);
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}
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void gps_powerdown(void) {
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GPS_PORT &= ~_BV(GPS_EN_PIN);
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}
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bool gps_enabled(void) {
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return gps_power;
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}
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void gps_init(Serial *ser) {
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serial = ser;
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memset(nmea_input_buf, 0, sizeof(nmea_input_buf));
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memset(nmea_parse_buf, 0, sizeof(nmea_parse_buf));
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gps_speed_knots = 0;
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gps_speed_kmh = 0;
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gps_bearing = 0;
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if (gps_detect()) {
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gps_installed = true;
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serial_setbaudrate_9600(1);
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gps_send_command(PMTK_SET_BAUD_57600);
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serial_setbaudrate_57600(1);
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gps_send_command(PMTK_API_SET_FIX_CTL_1HZ);
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gps_send_command(PMTK_SET_NMEA_OUTPUT_RMCGGA);
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GPS_DDR |= _BV(GPS_EN_PIN);
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if (gps_enabled()) { gps_powerup(); } else { gps_powerdown(); }
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} else {
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gps_installed = false;
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gps_power = false;
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}
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}
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void gps_update_rtc(void) {
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// TODO: implement this
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}
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void gps_jobs(void) {
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if (gps_enabled()) { gps_powerup(); } else { gps_powerdown(); }
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}
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void gps_send_command(const char *cmd) {
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fprintf_P(&serial->uart1, cmd);
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}
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void gps_nmea_parse(uint8_t sentence_length) {
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if (sentence_length > 4) {
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if (nmea_parse_buf[sentence_length-4] == '*') {
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uint16_t checksum = gps_nmea_parse_hex(nmea_parse_buf[sentence_length-3]);
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checksum *= 16;
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checksum += gps_nmea_parse_hex(nmea_parse_buf[sentence_length-2]);
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for (uint8_t i=1; i < sentence_length-4; i++) {
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checksum ^= nmea_parse_buf[i];
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}
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if (checksum != 0) {
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return;
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} else {
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// Parse GGA sentence
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if (strstr(nmea_parse_buf, "$GPGGA")) {
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char *pointer = nmea_parse_buf;
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// Parse UTC time
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pointer = strchr(pointer, ',')+1;
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uint32_t nmea_time = (float)atof(pointer);
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// Parse latitude
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pointer = strchr(pointer, ',')+1;
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char nmea_lat_deg_str[3];
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nmea_lat_deg_str[0] = pointer[0];
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nmea_lat_deg_str[1] = pointer[1];
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nmea_lat_deg_str[2] = '\0';
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char nmea_lat_min_str[3];
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nmea_lat_min_str[0] = pointer[2];
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nmea_lat_min_str[1] = pointer[3];
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nmea_lat_min_str[2] = '\0';
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char nmea_lat_dec_str[5];
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nmea_lat_dec_str[0] = pointer[5];
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nmea_lat_dec_str[1] = pointer[6];
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nmea_lat_dec_str[2] = pointer[7];
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nmea_lat_dec_str[3] = pointer[8];
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nmea_lat_dec_str[4] = '\0';
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// Parse latitude sign
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pointer = strchr(pointer, ',')+1;
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char nmea_lat_sign = pointer[0];
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// Parse longtitude
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pointer = strchr(pointer, ',')+1;
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char nmea_lon_deg_str[4];
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nmea_lon_deg_str[0] = pointer[0];
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nmea_lon_deg_str[1] = pointer[1];
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nmea_lon_deg_str[2] = pointer[2];
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nmea_lon_deg_str[3] = '\0';
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char nmea_lon_min_str[3];
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nmea_lon_min_str[0] = pointer[3];
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nmea_lon_min_str[1] = pointer[4];
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nmea_lon_min_str[2] = '\0';
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char nmea_lon_dec_str[5];
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nmea_lon_dec_str[0] = pointer[6];
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nmea_lon_dec_str[1] = pointer[7];
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nmea_lon_dec_str[2] = pointer[8];
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nmea_lon_dec_str[3] = pointer[9];
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nmea_lon_dec_str[4] = '\0';
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// Parse longtitude sign
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pointer = strchr(pointer, ',')+1;
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char nmea_lon_sign = pointer[0];
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// Get fix quality
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pointer = strchr(pointer, ',')+1;
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uint8_t nmea_fix = atoi(pointer);
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if (nmea_fix == 1) {
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gps_fix = true;
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} else {
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gps_fix = false;
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}
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if (gps_fix) {
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// Set times
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gps_t_hour = nmea_time / 10000;
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gps_t_minute = (nmea_time % 10000) / 100;
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gps_t_second = (nmea_time % 100);
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gps_update_rtc();
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// Set latitude and longtitude
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gps_lat_degrees = atoi(nmea_lat_deg_str);
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gps_lat_minutes = atoi(nmea_lat_min_str);
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gps_lat_seconds = (atoi(nmea_lat_dec_str)/10000.0)*60.0;
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gps_lon_degrees = atoi(nmea_lon_deg_str);
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gps_lon_minutes = atoi(nmea_lon_min_str);
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gps_lon_seconds = (atoi(nmea_lon_dec_str)/10000.0)*60.0;
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gps_lat = gps_lat_degrees + (gps_lat_minutes/60.0) + (gps_lat_seconds/3600.0);
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gps_lon = gps_lon_degrees + (gps_lon_minutes/60.0) + (gps_lon_seconds/3600.0);
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// Get satellites
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pointer = strchr(pointer, ',')+1;
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gps_sats = atoi(pointer);
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// Get horizontal dilution of position
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pointer = strchr(pointer, ',')+1;
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gps_hdop = atof(pointer);
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// Get altitude
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pointer = strchr(pointer, ',')+1;
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gps_altitude = atof(pointer);
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// Ignore altitude unit reference
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pointer = strchr(pointer, ',')+1;
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// Get geoid height
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pointer = strchr(pointer, ',')+1;
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gps_geoid_height = atof(pointer);
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// TODO: Check this calculation
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gps_height_above_msl = gps_geoid_height + gps_altitude;
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// Ignore geoid height unit reference
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pointer = strchr(pointer, ',')+1;
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gps_lat_sign = nmea_lat_sign;
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gps_lon_sign = nmea_lon_sign;
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gps_lat *= (gps_lat_sign == 'N' ? 1 : -1);
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gps_lon *= (gps_lon_sign == 'E' ? 1 : -1);
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// TODO: Remove this
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// printf("GPS fix: %d\r\n", nmea_fix);
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// printf("GPS satellites: %d\r\n", gps_sats);
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// printf("GPS latitude: %d\" %d' %.2fs %c\r\n", gps_lat_degrees, gps_lat_minutes, gps_lat_seconds, gps_lat_sign);
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// printf("GPS longtitude: %d\" %d' %.2fs %c\r\n", gps_lon_degrees, gps_lon_minutes, gps_lon_seconds, gps_lon_sign);
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// printf("GPS coords: %.6f,%.6f\r\n", gps_lat, gps_lon);
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// printf("GPS speed %.2f Km/h\r\n", gps_speed_kmh);
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// printf("GPS speed %.2f knots\r\n", gps_speed_knots);
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// printf("GPS bearing %.2f\r\n", gps_bearing);
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// printf("GPS height above MSL: %.2f\r\n", gps_height_above_msl);
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// printf("GPS altitude: %.2f\r\n", gps_altitude);
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// printf("GPS geoid height: %.2f\r\n", gps_geoid_height);
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// printf("GPS HDOP: %.2f\r\n", gps_hdop);
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// printf("GPS time %d:%d:%d UTC\r\n", gps_t_hour, gps_t_minute, gps_t_second);
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}
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}
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// Parse RMC sentence
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if (strstr(nmea_parse_buf, "$GPRMC")) {
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if (gps_fix) {
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char *pointer = nmea_parse_buf;
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// Ignore UTC time
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pointer = strchr(pointer, ',')+1;
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// Ignore navigation receiver warning
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pointer = strchr(pointer, ',')+1;
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// Ignore latitude
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pointer = strchr(pointer, ',')+1;
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// Ignore latitude sign
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pointer = strchr(pointer, ',')+1;
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// Ignore longtitude
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pointer = strchr(pointer, ',')+1;
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// Ignore longtitude sign
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pointer = strchr(pointer, ',')+1;
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// Get ground speed
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pointer = strchr(pointer, ',')+1;
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gps_speed_knots = atof(pointer);
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gps_speed_kmh = gps_speed_knots * 1.852;
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// Get bearing
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pointer = strchr(pointer, ',')+1;
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gps_bearing = atof(pointer);
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} else {
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gps_speed_knots = 0;
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gps_speed_kmh = 0;
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}
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}
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}
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}
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}
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}
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void gps_serial_callback(char byte) {
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if (byte == '\n') {
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for (uint8_t i = 0; i < NMEA_MAX_LENGTH; i++)
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nmea_parse_buf[i] = nmea_input_buf[i];
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memset(nmea_input_buf, 0, sizeof(nmea_input_buf));
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gps_nmea_parse(nmea_read_length);
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nmea_read_length = 0;
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} else {
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if (nmea_read_length < NMEA_MAX_LENGTH) {
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nmea_input_buf[nmea_read_length++] = byte;
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}
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}
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}
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void gps_poll(void) {
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while (!fifo_isempty_locked(&uart1FIFO)) {
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char sbyte = fifo_pop_locked(&uart1FIFO);
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gps_serial_callback(sbyte);
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}
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}
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uint8_t gps_nmea_parse_hex(char c) {
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if (c < '0')
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return 0;
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if (c <= '9')
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return c - '0';
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if (c < 'A')
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return 0;
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if (c <= 'F')
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return (c - 'A')+10;
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return 0;
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}
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