diff --git a/.gitmodules b/.gitmodules
index 40fab32..c61bf68 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +1,6 @@
 [submodule "components/u8g2"]
 	path = components/u8g2
 	url = git@github.com:liebman/u8g2
+[submodule "components/minmea/minmea"]
+	path = components/minmea/minmea
+	url = https://github.com/kosma/minmea.git
diff --git a/components/minmea/component.mk b/components/minmea/component.mk
new file mode 100644
index 0000000..5698cf7
--- /dev/null
+++ b/components/minmea/component.mk
@@ -0,0 +1,4 @@
+COMPONENT_OBJS := minmea/minmea.o
+COMPONENT_SRCDIRS := minmea
+COMPONENT_ADD_INCLUDEDIRS := minmea
+CPPFLAGS += -Dtimegm=mktime
diff --git a/components/minmea/minmea b/components/minmea/minmea
new file mode 160000
index 0000000..cd27e72
--- /dev/null
+++ b/components/minmea/minmea
@@ -0,0 +1 @@
+Subproject commit cd27e72970cd50b46e9c95c1c0076a49c1ceaf33
diff --git a/components/u8g2 b/components/u8g2
index 6bcf57f..ea7dbc4 160000
--- a/components/u8g2
+++ b/components/u8g2
@@ -1 +1 @@
-Subproject commit 6bcf57f2ae2d604e4954ea776d1eef1c0f3aed5e
+Subproject commit ea7dbc407cd68419322da57cdbdfc00521c86458
diff --git a/main/minmea/COPYING b/main/minmea/COPYING
deleted file mode 100644
index c6c7def..0000000
--- a/main/minmea/COPYING
+++ /dev/null
@@ -1,13 +0,0 @@
-        DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
-                    Version 2, December 2004
-
- Copyright (C) 2004 Sam Hocevar <sam@hocevar.net>
-
- Everyone is permitted to copy and distribute verbatim or modified
- copies of this license document, and changing it is allowed as long
- as the name is changed.
-
-            DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
-   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
-
-  0. You just DO WHAT THE FUCK YOU WANT TO.
diff --git a/main/minmea/minmea.c b/main/minmea/minmea.c
deleted file mode 100644
index e45b019..0000000
--- a/main/minmea/minmea.c
+++ /dev/null
@@ -1,645 +0,0 @@
-/*
- * Copyright © 2014 Kosma Moczek <kosma@cloudyourcar.com>
- * This program is free software. It comes without any warranty, to the extent
- * permitted by applicable law. You can redistribute it and/or modify it under
- * the terms of the Do What The Fuck You Want To Public License, Version 2, as
- * published by Sam Hocevar. See the COPYING file for more details.
- */
-
-#include "minmea.h"
-
-#include <stdlib.h>
-#include <string.h>
-#include <ctype.h>
-#include <stdarg.h>
-#include <time.h>
-
-#define boolstr(s) ((s) ? "true" : "false")
-
-static int hex2int(char c)
-{
-    if (c >= '0' && c <= '9')
-        return c - '0';
-    if (c >= 'A' && c <= 'F')
-        return c - 'A' + 10;
-    if (c >= 'a' && c <= 'f')
-        return c - 'a' + 10;
-    return -1;
-}
-
-uint8_t minmea_checksum(const char *sentence)
-{
-    // Support senteces with or without the starting dollar sign.
-    if (*sentence == '$')
-        sentence++;
-
-    uint8_t checksum = 0x00;
-
-    // The optional checksum is an XOR of all bytes between "$" and "*".
-    while (*sentence && *sentence != '*')
-        checksum ^= *sentence++;
-
-    return checksum;
-}
-
-bool minmea_check(const char *sentence, bool strict)
-{
-    uint8_t checksum = 0x00;
-
-    // Sequence length is limited.
-    if (strlen(sentence) > MINMEA_MAX_LENGTH + 3)
-        return false;
-
-    // A valid sentence starts with "$".
-    if (*sentence++ != '$')
-        return false;
-
-    // The optional checksum is an XOR of all bytes between "$" and "*".
-    while (*sentence && *sentence != '*' && isprint((unsigned char) *sentence))
-        checksum ^= *sentence++;
-
-    // If checksum is present...
-    if (*sentence == '*') {
-        // Extract checksum.
-        sentence++;
-        int upper = hex2int(*sentence++);
-        if (upper == -1)
-            return false;
-        int lower = hex2int(*sentence++);
-        if (lower == -1)
-            return false;
-        int expected = upper << 4 | lower;
-
-        // Check for checksum mismatch.
-        if (checksum != expected)
-            return false;
-    } else if (strict) {
-        // Discard non-checksummed frames in strict mode.
-        return false;
-    }
-
-    // The only stuff allowed at this point is a newline.
-    if (*sentence && strcmp(sentence, "\n") && strcmp(sentence, "\r\n"))
-        return false;
-
-    return true;
-}
-
-static inline bool minmea_isfield(char c) {
-    return isprint((unsigned char) c) && c != ',' && c != '*';
-}
-
-bool minmea_scan(const char *sentence, const char *format, ...)
-{
-    bool result = false;
-    bool optional = false;
-    va_list ap;
-    va_start(ap, format);
-
-    const char *field = sentence;
-#define next_field() \
-    do { \
-        /* Progress to the next field. */ \
-        while (minmea_isfield(*sentence)) \
-            sentence++; \
-        /* Make sure there is a field there. */ \
-        if (*sentence == ',') { \
-            sentence++; \
-            field = sentence; \
-        } else { \
-            field = NULL; \
-        } \
-    } while (0)
-
-    while (*format) {
-        char type = *format++;
-
-        if (type == ';') {
-            // All further fields are optional.
-            optional = true;
-            continue;
-        }
-
-        if (!field && !optional) {
-            // Field requested but we ran out if input. Bail out.
-            goto parse_error;
-        }
-
-        switch (type) {
-            case 'c': { // Single character field (char).
-                char value = '\0';
-
-                if (field && minmea_isfield(*field))
-                    value = *field;
-
-                *va_arg(ap, char *) = value;
-            } break;
-
-            case 'd': { // Single character direction field (int).
-                int value = 0;
-
-                if (field && minmea_isfield(*field)) {
-                    switch (*field) {
-                        case 'N':
-                        case 'E':
-                            value = 1;
-                            break;
-                        case 'S':
-                        case 'W':
-                            value = -1;
-                            break;
-                        default:
-                            goto parse_error;
-                    }
-                }
-
-                *va_arg(ap, int *) = value;
-            } break;
-
-            case 'f': { // Fractional value with scale (struct minmea_float).
-                int sign = 0;
-                int_least32_t value = -1;
-                int_least32_t scale = 0;
-
-                if (field) {
-                    while (minmea_isfield(*field)) {
-                        if (*field == '+' && !sign && value == -1) {
-                            sign = 1;
-                        } else if (*field == '-' && !sign && value == -1) {
-                            sign = -1;
-                        } else if (isdigit((unsigned char) *field)) {
-                            int digit = *field - '0';
-                            if (value == -1)
-                                value = 0;
-                            if (value > (INT_LEAST32_MAX-digit) / 10) {
-                                /* we ran out of bits, what do we do? */
-                                if (scale) {
-                                    /* truncate extra precision */
-                                    break;
-                                } else {
-                                    /* integer overflow. bail out. */
-                                    goto parse_error;
-                                }
-                            }
-                            value = (10 * value) + digit;
-                            if (scale)
-                                scale *= 10;
-                        } else if (*field == '.' && scale == 0) {
-                            scale = 1;
-                        } else if (*field == ' ') {
-                            /* Allow spaces at the start of the field. Not NMEA
-                             * conformant, but some modules do this. */
-                            if (sign != 0 || value != -1 || scale != 0)
-                                goto parse_error;
-                        } else {
-                            goto parse_error;
-                        }
-                        field++;
-                    }
-                }
-
-                if ((sign || scale) && value == -1)
-                    goto parse_error;
-
-                if (value == -1) {
-                    /* No digits were scanned. */
-                    value = 0;
-                    scale = 0;
-                } else if (scale == 0) {
-                    /* No decimal point. */
-                    scale = 1;
-                }
-                if (sign)
-                    value *= sign;
-
-                *va_arg(ap, struct minmea_float *) = (struct minmea_float) {value, scale};
-            } break;
-
-            case 'i': { // Integer value, default 0 (int).
-                int value = 0;
-
-                if (field) {
-                    char *endptr;
-                    value = strtol(field, &endptr, 10);
-                    if (minmea_isfield(*endptr))
-                        goto parse_error;
-                }
-
-                *va_arg(ap, int *) = value;
-            } break;
-
-            case 's': { // String value (char *).
-                char *buf = va_arg(ap, char *);
-
-                if (field) {
-                    while (minmea_isfield(*field))
-                        *buf++ = *field++;
-                }
-
-                *buf = '\0';
-            } break;
-
-            case 't': { // NMEA talker+sentence identifier (char *).
-                // This field is always mandatory.
-                if (!field)
-                    goto parse_error;
-
-                if (field[0] != '$')
-                    goto parse_error;
-                for (int f=0; f<5; f++)
-                    if (!minmea_isfield(field[1+f]))
-                        goto parse_error;
-
-                char *buf = va_arg(ap, char *);
-                memcpy(buf, field+1, 5);
-                buf[5] = '\0';
-            } break;
-
-            case 'D': { // Date (int, int, int), -1 if empty.
-                struct minmea_date *date = va_arg(ap, struct minmea_date *);
-
-                int d = -1, m = -1, y = -1;
-
-                if (field && minmea_isfield(*field)) {
-                    // Always six digits.
-                    for (int f=0; f<6; f++)
-                        if (!isdigit((unsigned char) field[f]))
-                            goto parse_error;
-
-                    char dArr[] = {field[0], field[1], '\0'};
-                    char mArr[] = {field[2], field[3], '\0'};
-                    char yArr[] = {field[4], field[5], '\0'};
-                    d = strtol(dArr, NULL, 10);
-                    m = strtol(mArr, NULL, 10);
-                    y = strtol(yArr, NULL, 10);
-                }
-
-                date->day = d;
-                date->month = m;
-                date->year = y;
-            } break;
-
-            case 'T': { // Time (int, int, int, int), -1 if empty.
-                struct minmea_time *time_ = va_arg(ap, struct minmea_time *);
-
-                int h = -1, i = -1, s = -1, u = -1;
-
-                if (field && minmea_isfield(*field)) {
-                    // Minimum required: integer time.
-                    for (int f=0; f<6; f++)
-                        if (!isdigit((unsigned char) field[f]))
-                            goto parse_error;
-
-                    char hArr[] = {field[0], field[1], '\0'};
-                    char iArr[] = {field[2], field[3], '\0'};
-                    char sArr[] = {field[4], field[5], '\0'};
-                    h = strtol(hArr, NULL, 10);
-                    i = strtol(iArr, NULL, 10);
-                    s = strtol(sArr, NULL, 10);
-                    field += 6;
-
-                    // Extra: fractional time. Saved as microseconds.
-                    if (*field++ == '.') {
-                        uint32_t value = 0;
-                        uint32_t scale = 1000000LU;
-                        while (isdigit((unsigned char) *field) && scale > 1) {
-                            value = (value * 10) + (*field++ - '0');
-                            scale /= 10;
-                        }
-                        u = value * scale;
-                    } else {
-                        u = 0;
-                    }
-                }
-
-                time_->hours = h;
-                time_->minutes = i;
-                time_->seconds = s;
-                time_->microseconds = u;
-            } break;
-
-            case '_': { // Ignore the field.
-            } break;
-
-            default: { // Unknown.
-                goto parse_error;
-            } break;
-        }
-
-        next_field();
-    }
-
-    result = true;
-
-parse_error:
-    va_end(ap);
-    return result;
-}
-
-bool minmea_talker_id(char talker[3], const char *sentence)
-{
-    char type[6];
-    if (!minmea_scan(sentence, "t", type))
-        return false;
-
-    talker[0] = type[0];
-    talker[1] = type[1];
-    talker[2] = '\0';
-
-    return true;
-}
-
-enum minmea_sentence_id minmea_sentence_id(const char *sentence, bool strict)
-{
-    if (!minmea_check(sentence, strict))
-        return MINMEA_INVALID;
-
-    char type[6];
-    if (!minmea_scan(sentence, "t", type))
-        return MINMEA_INVALID;
-
-    if (!strcmp(type+2, "RMC"))
-        return MINMEA_SENTENCE_RMC;
-    if (!strcmp(type+2, "GGA"))
-        return MINMEA_SENTENCE_GGA;
-    if (!strcmp(type+2, "GSA"))
-        return MINMEA_SENTENCE_GSA;
-    if (!strcmp(type+2, "GLL"))
-        return MINMEA_SENTENCE_GLL;
-    if (!strcmp(type+2, "GST"))
-        return MINMEA_SENTENCE_GST;
-    if (!strcmp(type+2, "GSV"))
-        return MINMEA_SENTENCE_GSV;
-    if (!strcmp(type+2, "VTG"))
-        return MINMEA_SENTENCE_VTG;
-    if (!strcmp(type+2, "ZDA"))
-        return MINMEA_SENTENCE_ZDA;
-
-    return MINMEA_UNKNOWN;
-}
-
-bool minmea_parse_rmc(struct minmea_sentence_rmc *frame, const char *sentence)
-{
-    // $GPRMC,081836,A,3751.65,S,14507.36,E,000.0,360.0,130998,011.3,E*62
-    char type[6];
-    char validity;
-    int latitude_direction;
-    int longitude_direction;
-    int variation_direction;
-    if (!minmea_scan(sentence, "tTcfdfdffDfd",
-            type,
-            &frame->time,
-            &validity,
-            &frame->latitude, &latitude_direction,
-            &frame->longitude, &longitude_direction,
-            &frame->speed,
-            &frame->course,
-            &frame->date,
-            &frame->variation, &variation_direction))
-        return false;
-    if (strcmp(type+2, "RMC"))
-        return false;
-
-    frame->valid = (validity == 'A');
-    frame->latitude.value *= latitude_direction;
-    frame->longitude.value *= longitude_direction;
-    frame->variation.value *= variation_direction;
-
-    return true;
-}
-
-bool minmea_parse_gga(struct minmea_sentence_gga *frame, const char *sentence)
-{
-    // $GPGGA,123519,4807.038,N,01131.000,E,1,08,0.9,545.4,M,46.9,M,,*47
-    char type[6];
-    int latitude_direction;
-    int longitude_direction;
-
-    if (!minmea_scan(sentence, "tTfdfdiiffcfci_",
-            type,
-            &frame->time,
-            &frame->latitude, &latitude_direction,
-            &frame->longitude, &longitude_direction,
-            &frame->fix_quality,
-            &frame->satellites_tracked,
-            &frame->hdop,
-            &frame->altitude, &frame->altitude_units,
-            &frame->height, &frame->height_units,
-            &frame->dgps_age))
-        return false;
-    if (strcmp(type+2, "GGA"))
-        return false;
-
-    frame->latitude.value *= latitude_direction;
-    frame->longitude.value *= longitude_direction;
-
-    return true;
-}
-
-bool minmea_parse_gsa(struct minmea_sentence_gsa *frame, const char *sentence)
-{
-    // $GPGSA,A,3,04,05,,09,12,,,24,,,,,2.5,1.3,2.1*39
-    char type[6];
-
-    if (!minmea_scan(sentence, "tciiiiiiiiiiiiifff",
-            type,
-            &frame->mode,
-            &frame->fix_type,
-            &frame->sats[0],
-            &frame->sats[1],
-            &frame->sats[2],
-            &frame->sats[3],
-            &frame->sats[4],
-            &frame->sats[5],
-            &frame->sats[6],
-            &frame->sats[7],
-            &frame->sats[8],
-            &frame->sats[9],
-            &frame->sats[10],
-            &frame->sats[11],
-            &frame->pdop,
-            &frame->hdop,
-            &frame->vdop))
-        return false;
-    if (strcmp(type+2, "GSA"))
-        return false;
-
-    return true;
-}
-
-bool minmea_parse_gll(struct minmea_sentence_gll *frame, const char *sentence)
-{
-    // $GPGLL,3723.2475,N,12158.3416,W,161229.487,A,A*41$;
-    char type[6];
-    int latitude_direction;
-    int longitude_direction;
-
-    if (!minmea_scan(sentence, "tfdfdTc;c",
-            type,
-            &frame->latitude, &latitude_direction,
-            &frame->longitude, &longitude_direction,
-            &frame->time,
-            &frame->status,
-            &frame->mode))
-        return false;
-    if (strcmp(type+2, "GLL"))
-        return false;
-
-    frame->latitude.value *= latitude_direction;
-    frame->longitude.value *= longitude_direction;
-
-    return true;
-}
-
-bool minmea_parse_gst(struct minmea_sentence_gst *frame, const char *sentence)
-{
-    // $GPGST,024603.00,3.2,6.6,4.7,47.3,5.8,5.6,22.0*58
-    char type[6];
-
-    if (!minmea_scan(sentence, "tTfffffff",
-            type,
-            &frame->time,
-            &frame->rms_deviation,
-            &frame->semi_major_deviation,
-            &frame->semi_minor_deviation,
-            &frame->semi_major_orientation,
-            &frame->latitude_error_deviation,
-            &frame->longitude_error_deviation,
-            &frame->altitude_error_deviation))
-        return false;
-    if (strcmp(type+2, "GST"))
-        return false;
-
-    return true;
-}
-
-bool minmea_parse_gsv(struct minmea_sentence_gsv *frame, const char *sentence)
-{
-    // $GPGSV,3,1,11,03,03,111,00,04,15,270,00,06,01,010,00,13,06,292,00*74
-    // $GPGSV,3,3,11,22,42,067,42,24,14,311,43,27,05,244,00,,,,*4D
-    // $GPGSV,4,2,11,08,51,203,30,09,45,215,28*75
-    // $GPGSV,4,4,13,39,31,170,27*40
-    // $GPGSV,4,4,13*7B
-    char type[6];
-
-    if (!minmea_scan(sentence, "tiii;iiiiiiiiiiiiiiii",
-            type,
-            &frame->total_msgs,
-            &frame->msg_nr,
-            &frame->total_sats,
-            &frame->sats[0].nr,
-            &frame->sats[0].elevation,
-            &frame->sats[0].azimuth,
-            &frame->sats[0].snr,
-            &frame->sats[1].nr,
-            &frame->sats[1].elevation,
-            &frame->sats[1].azimuth,
-            &frame->sats[1].snr,
-            &frame->sats[2].nr,
-            &frame->sats[2].elevation,
-            &frame->sats[2].azimuth,
-            &frame->sats[2].snr,
-            &frame->sats[3].nr,
-            &frame->sats[3].elevation,
-            &frame->sats[3].azimuth,
-            &frame->sats[3].snr
-            )) {
-        return false;
-    }
-    if (strcmp(type+2, "GSV"))
-        return false;
-
-    return true;
-}
-
-bool minmea_parse_vtg(struct minmea_sentence_vtg *frame, const char *sentence)
-{
-    // $GPVTG,054.7,T,034.4,M,005.5,N,010.2,K*48
-    // $GPVTG,156.1,T,140.9,M,0.0,N,0.0,K*41
-    // $GPVTG,096.5,T,083.5,M,0.0,N,0.0,K,D*22
-    // $GPVTG,188.36,T,,M,0.820,N,1.519,K,A*3F
-    char type[6];
-    char c_true, c_magnetic, c_knots, c_kph, c_faa_mode;
-
-    if (!minmea_scan(sentence, "tfcfcfcfc;c",
-            type,
-            &frame->true_track_degrees,
-            &c_true,
-            &frame->magnetic_track_degrees,
-            &c_magnetic,
-            &frame->speed_knots,
-            &c_knots,
-            &frame->speed_kph,
-            &c_kph,
-            &c_faa_mode))
-        return false;
-    if (strcmp(type+2, "VTG"))
-        return false;
-    // check chars
-    if (c_true != 'T' ||
-        c_magnetic != 'M' ||
-        c_knots != 'N' ||
-        c_kph != 'K')
-        return false;
-    frame->faa_mode = c_faa_mode;
-
-    return true;
-}
-
-bool minmea_parse_zda(struct minmea_sentence_zda *frame, const char *sentence)
-{
-  // $GPZDA,201530.00,04,07,2002,00,00*60
-  char type[6];
-
-  if(!minmea_scan(sentence, "tTiiiii",
-          type,
-          &frame->time,
-          &frame->date.day,
-          &frame->date.month,
-          &frame->date.year,
-          &frame->hour_offset,
-          &frame->minute_offset))
-      return false;
-  if (strcmp(type+2, "ZDA"))
-      return false;
-
-  // check offsets
-  if (abs(frame->hour_offset) > 13 ||
-      frame->minute_offset > 59 ||
-      frame->minute_offset < 0)
-      return false;
-
-  return true;
-}
-
-int minmea_gettime(struct timespec *ts, const struct minmea_date *date, const struct minmea_time *time_)
-{
-    if (date->year == -1 || time_->hours == -1)
-        return -1;
-
-    struct tm tm;
-    memset(&tm, 0, sizeof(tm));
-    if (date->year < 80) {
-        tm.tm_year = 2000 + date->year - 1900;  // 2000-2079
-    } else if (date->year >= 1900) {
-        tm.tm_year = date->year - 1900; // 4 digit year, use directly
-    } else {
-        tm.tm_year = date->year;    // 1980-1999
-    }
-    tm.tm_mon = date->month - 1;
-    tm.tm_mday = date->day;
-    tm.tm_hour = time_->hours;
-    tm.tm_min = time_->minutes;
-    tm.tm_sec = time_->seconds;
-
-    time_t timestamp = mktime(&tm);
-    if (timestamp != -1) {
-        ts->tv_sec = timestamp;
-        ts->tv_nsec = time_->microseconds * 1000;
-        return 0;
-    } else {
-        return -1;
-    }
-}
-
-/* vim: set ts=4 sw=4 et: */
diff --git a/main/minmea/minmea.h b/main/minmea/minmea.h
deleted file mode 100644
index b80124c..0000000
--- a/main/minmea/minmea.h
+++ /dev/null
@@ -1,261 +0,0 @@
-/*
- * Copyright © 2014 Kosma Moczek <kosma@cloudyourcar.com>
- * This program is free software. It comes without any warranty, to the extent
- * permitted by applicable law. You can redistribute it and/or modify it under
- * the terms of the Do What The Fuck You Want To Public License, Version 2, as
- * published by Sam Hocevar. See the COPYING file for more details.
- */
-
-#ifndef MINMEA_H
-#define MINMEA_H
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-#include <stdio.h>
-#include <stdint.h>
-#include <stdbool.h>
-#include <errno.h>
-#include <time.h>
-#include <math.h>
-#ifdef MINMEA_INCLUDE_COMPAT
-#include <minmea_compat.h>
-#endif
-
-#define MINMEA_MAX_LENGTH 80
-
-enum minmea_sentence_id {
-    MINMEA_INVALID = -1,
-    MINMEA_UNKNOWN = 0,
-    MINMEA_SENTENCE_RMC,
-    MINMEA_SENTENCE_GGA,
-    MINMEA_SENTENCE_GSA,
-    MINMEA_SENTENCE_GLL,
-    MINMEA_SENTENCE_GST,
-    MINMEA_SENTENCE_GSV,
-    MINMEA_SENTENCE_VTG,
-    MINMEA_SENTENCE_ZDA,
-};
-
-struct minmea_float {
-    int_least32_t value;
-    int_least32_t scale;
-};
-
-struct minmea_date {
-    int day;
-    int month;
-    int year;
-};
-
-struct minmea_time {
-    int hours;
-    int minutes;
-    int seconds;
-    int microseconds;
-};
-
-struct minmea_sentence_rmc {
-    struct minmea_time time;
-    bool valid;
-    struct minmea_float latitude;
-    struct minmea_float longitude;
-    struct minmea_float speed;
-    struct minmea_float course;
-    struct minmea_date date;
-    struct minmea_float variation;
-};
-
-struct minmea_sentence_gga {
-    struct minmea_time time;
-    struct minmea_float latitude;
-    struct minmea_float longitude;
-    int fix_quality;
-    int satellites_tracked;
-    struct minmea_float hdop;
-    struct minmea_float altitude; char altitude_units;
-    struct minmea_float height; char height_units;
-    int dgps_age;
-};
-
-enum minmea_gll_status {
-    MINMEA_GLL_STATUS_DATA_VALID = 'A',
-    MINMEA_GLL_STATUS_DATA_NOT_VALID = 'V',
-};
-
-// FAA mode added to some fields in NMEA 2.3.
-enum minmea_faa_mode {
-    MINMEA_FAA_MODE_AUTONOMOUS = 'A',
-    MINMEA_FAA_MODE_DIFFERENTIAL = 'D',
-    MINMEA_FAA_MODE_ESTIMATED = 'E',
-    MINMEA_FAA_MODE_MANUAL = 'M',
-    MINMEA_FAA_MODE_SIMULATED = 'S',
-    MINMEA_FAA_MODE_NOT_VALID = 'N',
-    MINMEA_FAA_MODE_PRECISE = 'P',
-};
-
-struct minmea_sentence_gll {
-    struct minmea_float latitude;
-    struct minmea_float longitude;
-    struct minmea_time time;
-    char status;
-    char mode;
-};
-
-struct minmea_sentence_gst {
-    struct minmea_time time;
-    struct minmea_float rms_deviation;
-    struct minmea_float semi_major_deviation;
-    struct minmea_float semi_minor_deviation;
-    struct minmea_float semi_major_orientation;
-    struct minmea_float latitude_error_deviation;
-    struct minmea_float longitude_error_deviation;
-    struct minmea_float altitude_error_deviation;
-};
-
-enum minmea_gsa_mode {
-    MINMEA_GPGSA_MODE_AUTO = 'A',
-    MINMEA_GPGSA_MODE_FORCED = 'M',
-};
-
-enum minmea_gsa_fix_type {
-    MINMEA_GPGSA_FIX_NONE = 1,
-    MINMEA_GPGSA_FIX_2D = 2,
-    MINMEA_GPGSA_FIX_3D = 3,
-};
-
-struct minmea_sentence_gsa {
-    char mode;
-    int fix_type;
-    int sats[12];
-    struct minmea_float pdop;
-    struct minmea_float hdop;
-    struct minmea_float vdop;
-};
-
-struct minmea_sat_info {
-    int nr;
-    int elevation;
-    int azimuth;
-    int snr;
-};
-
-struct minmea_sentence_gsv {
-    int total_msgs;
-    int msg_nr;
-    int total_sats;
-    struct minmea_sat_info sats[4];
-};
-
-struct minmea_sentence_vtg {
-    struct minmea_float true_track_degrees;
-    struct minmea_float magnetic_track_degrees;
-    struct minmea_float speed_knots;
-    struct minmea_float speed_kph;
-    enum minmea_faa_mode faa_mode;
-};
-
-struct minmea_sentence_zda {
-    struct minmea_time time;
-    struct minmea_date date;
-    int hour_offset;
-    int minute_offset;
-};
-
-/**
- * Calculate raw sentence checksum. Does not check sentence integrity.
- */
-uint8_t minmea_checksum(const char *sentence);
-
-/**
- * Check sentence validity and checksum. Returns true for valid sentences.
- */
-bool minmea_check(const char *sentence, bool strict);
-
-/**
- * Determine talker identifier.
- */
-bool minmea_talker_id(char talker[3], const char *sentence);
-
-/**
- * Determine sentence identifier.
- */
-enum minmea_sentence_id minmea_sentence_id(const char *sentence, bool strict);
-
-/**
- * Scanf-like processor for NMEA sentences. Supports the following formats:
- * c - single character (char *)
- * d - direction, returned as 1/-1, default 0 (int *)
- * f - fractional, returned as value + scale (int *, int *)
- * i - decimal, default zero (int *)
- * s - string (char *)
- * t - talker identifier and type (char *)
- * T - date/time stamp (int *, int *, int *)
- * Returns true on success. See library source code for details.
- */
-bool minmea_scan(const char *sentence, const char *format, ...);
-
-/*
- * Parse a specific type of sentence. Return true on success.
- */
-bool minmea_parse_rmc(struct minmea_sentence_rmc *frame, const char *sentence);
-bool minmea_parse_gga(struct minmea_sentence_gga *frame, const char *sentence);
-bool minmea_parse_gsa(struct minmea_sentence_gsa *frame, const char *sentence);
-bool minmea_parse_gll(struct minmea_sentence_gll *frame, const char *sentence);
-bool minmea_parse_gst(struct minmea_sentence_gst *frame, const char *sentence);
-bool minmea_parse_gsv(struct minmea_sentence_gsv *frame, const char *sentence);
-bool minmea_parse_vtg(struct minmea_sentence_vtg *frame, const char *sentence);
-bool minmea_parse_zda(struct minmea_sentence_zda *frame, const char *sentence);
-
-/**
- * Convert GPS UTC date/time representation to a UNIX timestamp.
- */
-int minmea_gettime(struct timespec *ts, const struct minmea_date *date, const struct minmea_time *time_);
-
-/**
- * Rescale a fixed-point value to a different scale. Rounds towards zero.
- */
-static inline int_least32_t minmea_rescale(struct minmea_float *f, int_least32_t new_scale)
-{
-    if (f->scale == 0)
-        return 0;
-    if (f->scale == new_scale)
-        return f->value;
-    if (f->scale > new_scale)
-        return (f->value + ((f->value > 0) - (f->value < 0)) * f->scale/new_scale/2) / (f->scale/new_scale);
-    else
-        return f->value * (new_scale/f->scale);
-}
-
-/**
- * Convert a fixed-point value to a floating-point value.
- * Returns NaN for "unknown" values.
- */
-static inline float minmea_tofloat(struct minmea_float *f)
-{
-    if (f->scale == 0)
-        return NAN;
-    return (float) f->value / (float) f->scale;
-}
-
-/**
- * Convert a raw coordinate to a floating point DD.DDD... value.
- * Returns NaN for "unknown" values.
- */
-static inline float minmea_tocoord(struct minmea_float *f)
-{
-    if (f->scale == 0)
-        return NAN;
-    int_least32_t degrees = f->value / (f->scale * 100);
-    int_least32_t minutes = f->value % (f->scale * 100);
-    return (float) degrees + (float) minutes / (60 * f->scale);
-}
-
-#ifdef __cplusplus
-}
-#endif
-
-#endif /* MINMEA_H */
-
-/* vim: set ts=4 sw=4 et: */