Configurations.md

Configuration

All configuration items are conditional compilations: a #define controls an #if/#endif section. Delete or comment out any items to be excluded from your build. Where possible, checks are performed to verify that you have chosen a "valid" configuration: you may see #error messages in the build log. See also Troubleshooting section below.

####gps_fix The following configuration items are near the top of GPSfix_cfg.h:

// Enable/Disable individual parts of a fix, as parsed from fields of a $GPxxx sentence
#define GPS_FIX_DATE
#define GPS_FIX_TIME
#define GPS_FIX_LOCATION
#define GPS_FIX_ALTITUDE
#define GPS_FIX_SPEED
#define GPS_FIX_HEADING
#define GPS_FIX_SATELLITES
#define GPS_FIX_HDOP
#define GPS_FIX_VDOP
#define GPS_FIX_PDOP
#define GPS_FIX_LAT_ERR
#define GPS_FIX_LON_ERR
#define GPS_FIX_ALT_ERR

####NMEAGPS The following configuration items are near the top of NMEAGPS_cfg.h. ####Enable/Disable parsing the fields of a $GPxxx sentence

#define NMEAGPS_PARSE_GGA
#define NMEAGPS_PARSE_GLL
#define NMEAGPS_PARSE_GSA
#define NMEAGPS_PARSE_GSV
#define NMEAGPS_PARSE_GST
#define NMEAGPS_PARSE_RMC
#define NMEAGPS_PARSE_VTG
#define NMEAGPS_PARSE_ZDA

Enable/disable the talker ID and manufacturer ID processing.

There are two kinds of NMEA sentences:

1. Standard NMEA sentences begin with "$ttccc", where "tt" is the talker ID (e.g., GP), and "ccc" is the variable-length sentence type (e.g., RMC).

   For example, "$GPGLL,..." is a GLL sentence (Geographic Lat/Long) transmitted by talker "GP". This is the most common talker ID. Some devices may report "$GNGLL,..." when a mix of GPS and non-GPS satellites have been used to determine the GLL data (e.g., GLONASS+GPS).

2. Proprietary NMEA sentences (i.e., those unique to a particular manufacturer) begin with "$Pmmmccc", where "P" is the NMEA-defined prefix indicator for proprietary messages, "mmm" is the 3-character manufacturer ID, and "ccc" is the variable-length sentence type (it can be empty).

No validation of manufacturer ID and talker ID is performed in this base class. For example, although "GP" is a common talker ID, it is not guaranteed to be transmitted by your particular device, and it IS NOT REQUIRED. If you need validation of these IDs, or you need to use the extra information provided by some devices, you have two independent options:

1. Enable SAVING the ID: When decode returns DECODE_COMPLETED, the talker_id and/or mfr_id members will contain ID bytes. The entire sentence will be parsed, perhaps modifying members of fix. You should enable one or both IDs if you want the information in all sentences and you also want to know the ID bytes. This adds 2 bytes of RAM for the talker ID, and 3 bytes of RAM for the manufacturer ID.

2. Enable PARSING the ID: The virtual parse_talker_id and parse_mfr_id will receive each ID character as it is received. If it is not a valid ID, return false to abort processing the rest of the sentence. No CPU time will be wasted on the invalid sentence, and no fix members will be modified. You should enable this if you want to ignore some IDs. You must override parse_talker_id and/or parse_mfr_id in a derived class.

#define NMEAGPS_SAVE_TALKER_ID
#define NMEAGPS_PARSE_TALKER_ID

#define NMEAGPS_SAVE_MFR_ID
#define NMEAGPS_PARSE_MFR_ID

###Disable derived types Although normally enabled, this can be disabled if you do not derive any classes from NMEAGPS, for slightly smaller/faster code.

#define NMEAGPS_DERIVED_TYPES

The ublox-specific files require this define (see ublox section).

###Enable/disable tracking the current satellite array You can also enable tracking the detailed information for each satellite, and how many satellites you want to track. Although many GPS receivers claim to have 66 channels of tracking, 16 is usually the maximum number of satellites tracked at any one time.

#define NMEAGPS_PARSE_SATELLITES
#define NMEAGPS_PARSE_SATELLITE_INFO
#define NMEAGPS_MAX_SATELLITES (20)

###Enable/disable accumulating fix data across sentences. When enabled, decode will perform implicit merging of fix data as it is parsed from a new sentence. Each field of a new sentence will invalidate, set and then validate the corresponding member of fix(). Any other fix data that was filled by a previous sentence is not invalidated. To enable implicit merging, uncomment this define:

#define NMEAGPS_ACCUMULATE_FIX

Implicit merging can eliminate the need for a second fix (i.e., reduced RAM), but it could prevent coherency. See Data Model - Merging for a discussion of the different types of merging.

####Floating-point output. Streamers.cpp is used by the example programs for printing members of fix(). It is not required for parsing the GPS data stream, and this file may be deleted. It is an example of checking validity flags and formatting the various members of fix() for textual streams (e.g., Serial prints or SD writes).

Streamers.cpp has one configuration item:

#define USE_FLOAT

This is local to this file, and is only used by the example programs. This file is not required unless you need to stream one of these types: bool, char, uint8_t, int16_t, uint16_t, int32_t, uint32_t, F() strings, gps_fix or NMEAGPS.

Most example programs have a choice for displaying fix information once per day. (Untested!)

#define PULSE_PER_DAY

####Typical configurations A few common configurations are defined as follows

Minimal: no fix members, no messages (pulse-per-second only)

DTL: date, time, lat/lon, GPRMC messsage only.

Nominal: date, time, lat/lon, altitude, speed, heading, number of satellites, HDOP, GPRMC and GPGGA messages.

Full: Nominal plus talker ID, VDOP, PDOP, lat/lon/alt errors, satellite array with satellite info, all messages, and parser statistics.

These configurations are available in the configs subdirectory.

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####Configurations of other libraries

TinyGPS uses the Nominal configuration + a second fix.

TinyGPSPlus uses the Nominal configuration + statistics + a second fix + timestamps for each fix member.

Adafruit_GPS uses the Nominal configuration + geoid height and IGNORES CHECKSUM!)