Second half...
// 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 two 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 parsed. 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_PARSE_PROPRIETARY
#ifdef NMEAGPS_PARSE_PROPRIETARY
//#define NMEAGPS_SAVE_MFR_ID
#define NMEAGPS_PARSE_MFR_ID
#endif
//------------------------------------------------------
// Enable/disable tracking the current satellite array and,
// optionally, all the info for each satellite.
//
//#define NMEAGPS_PARSE_SATELLITES
//#define NMEAGPS_PARSE_SATELLITE_INFO
#ifdef NMEAGPS_PARSE_SATELLITES
#define NMEAGPS_MAX_SATELLITES (20)
#ifndef GPS_FIX_SATELLITES
#error GPS_FIX_SATELLITES must be defined in GPSfix.h!
#endif
#endif
#if defined(NMEAGPS_PARSE_SATELLITE_INFO) & \
!defined(NMEAGPS_PARSE_SATELLITES)
#error NMEAGPS_PARSE_SATELLITES must be defined!
#endif
//------------------------------------------------------
// Enable/disable gathering interface statistics:
// CRC errors and number of sentences received
#define NMEAGPS_STATS
//------------------------------------------------------
// Configuration item for allowing derived types of NMEAGPS.
// If you derive classes from NMEAGPS, you *must* define NMEAGPS_DERIVED_TYPES.
// If not defined, virtuals are not used, with a slight size (2 bytes) and
// execution time savings.
//#define NMEAGPS_DERIVED_TYPES
#ifdef NMEAGPS_DERIVED_TYPES
#define NMEAGPS_VIRTUAL virtual
#else
#define NMEAGPS_VIRTUAL
#endif
//-----------------------------------
// See if DERIVED_TYPES is required
#if (defined(NMEAGPS_PARSE_TALKER_ID) | defined(NMEAGPS_PARSE_MFR_ID)) & \
!defined(NMEAGPS_DERIVED_TYPES)
#error You must define NMEAGPS_DERIVED_TYPES in NMEAGPS.h in order to parse Talker and/or Mfr IDs!
#endif
//------------------------------------------------------
// Becase the NMEA checksum is not very good at error detection, you can
// choose to enable additional validity checks. This trades a little more
// code and execution time for more reliability.
//
// Validation at the character level is a syntactic check only. For
// example, integer fields must contain characters in the range 0..9,
// latitude hemisphere letters can be 'N' or 'S'. Characters that are not
// valid for a particular field will cause the entire sentence to be
// rejected as an error, *regardless* of whether the checksum would pass.
#define NMEAGPS_VALIDATE_CHARS false
// Validation at the field level is a semantic check. For
// example, latitude degrees must be in the range -90..+90.
// Values that are not valid for a particular field will cause the
// entire sentence to be rejected as an error, *regardless* of whether the
// checksum would pass.
#define NMEAGPS_VALIDATE_FIELDS false
//------------------------------------------------------
// Some devices may omit trailing commas at the end of some
// sentences. This may prevent the last field from being
// parsed correctly, because the parser for some types keep
// the value in an intermediate state until the complete
// field is received (e.g., parseDDDMM, parseFloat and
// parseZDA).
//
// Enabling this will inject a simulated comma when the end
// of a sentence is received and the last field parser
// indicated that it still needs one.
#define NMEAGPS_COMMA_NEEDED
//------------------------------------------------------
// Some applications may want to recognize a sentence type
// without actually parsing any of the fields. Uncommenting
// this define will allow the nmeaMessage member to be set
// when *any* standard message is seen, even though that
// message is not enabled by a NMEAGPS_PARSE_xxx define above.
// No valid flags will be true for those sentences.
#define NMEAGPS_RECOGNIZE_ALL
//------------------------------------------------------
// Sometimes, a little extra space is needed to parse an intermediate form.
// This config items enables extra space.
//#define NMEAGPS_PARSING_SCRATCHPAD
//------------------------------------------------------
// If you need to know the exact UTC time at *any* time,
// not just after a fix arrives, you must calculate the
// offset between the Arduino micros() clock and the UTC
// time in a received fix. There are two ways to do this:
//
// 1) When the GPS quiet time ends and the new update interval begins.
// The timestamp will be set when the first character (the '
) of
// the new batch of sentences arrives from the GPS device. This is fairly
// accurate, but it will be delayed from the PPS edge by the GPS device's
// fix calculation time (usually ~100us). There is very little variance
// in this calculation time (usually < 30us), so all timestamps are
// delayed by a nearly-constant amount.
//
// NOTE: At update rates higher than 1Hz, the updates may arrive with
// some increasing variance.
//#define NMEAGPS_TIMESTAMP_FROM_INTERVAL
// 2) From the PPS pin of the GPS module. It is up to the application
// developer to decide how to capture that event. For example, you could:
//
// a) simply poll for it in loop and call UTCsecondStart(micros());
// b) use attachInterrupt to call a Pin Change Interrupt ISR to save
// the micros() at the time of the interrupt (see NMEAGPS.h), or
// c) connect the PPS to an Input Capture pin. Set the
// associated TIMER frequency, calculate the elapsed time
// since the PPS edge, and add that to the current micros().
//#define NMEAGPS_TIMESTAMP_FROM_PPS
#if defined( NMEAGPS_TIMESTAMP_FROM_INTERVAL ) &
defined( NMEAGPS_TIMESTAMP_FROM_PPS )
#error You cannot enable both TIMESTAMP_FROM_INTERVAL and PPS in NMEAGPS_cfg.h!
#endif
#endif