#include <Adafruit_GNSS.h>

Inheritance diagram for Adafruit_GNSS:

Public Member Functions
	Adafruit_GNSS (volatile char firstBuffer=NULL, volatile char secondBuffer=NULL, size_t capacity=0)
	Create a GNSS receiver using the shared bounded NMEA framer. More...

gnss_position_t	lastPosition () const
	Decode the latest complete line into an independent position result. More...

Public Member Functions inherited from Adafruit_NMEA
	Adafruit_NMEA (volatile char firstBuffer, volatile char secondBuffer, size_t capacity)
	Create a receiver using two caller-owned buffers. More...

	Adafruit_NMEA (const Adafruit_NMEA &other)=delete
	Copying is disabled to prevent sharing writable receive buffers. More...

Adafruit_NMEA &	operator= (const Adafruit_NMEA &other)=delete
	Assignment is disabled to prevent sharing writable receive buffers. More...

void	reset ()
	Discard partial and completed lines and clear all timestamps. More...

nmea_frame_status_t	feed (uint8_t byte, uint32_t receivedAtMs)
	Feed one byte into this receiver's bounded sentence buffer. More...

nmea_span_t	lastText () const
	Get the latest complete raw line without validating it again. More...

nmea_sentence_t	lastSentence () const
	Get views of the latest complete line, including invalid raw text. More...

uint32_t	sentenceStartedAt () const
	Get the start-marker timestamp of the latest complete line. More...

uint32_t	sentenceReceivedAt () const
	Get the LF timestamp of the latest complete line. More...

Static Public Member Functions
static gnss_coordinate_t	parseCoordinate (nmea_span_t coordinate, nmea_span_t hemisphere)
	Decode a latitude or longitude field and its hemisphere. More...

static size_t	formatCoordinate (char *output, size_t capacity, const gnss_coordinate_t &coordinate)
	Format exact coordinate components as signed decimal degrees. More...

static gnss_position_t	parsePosition (nmea_span_t type, nmea_span_t fields)
	Decode a GGA, RMC, or GLL position without retaining receiver state. More...

static gnss_position_t	parsePosition (const nmea_sentence_t &sentence)
	Route a validated standard NMEA sentence to the position decoder. More...

static gnss_time_t	parseTime (nmea_span_t field)
	Decode a complete UTC hhmmss[.fraction] field. More...

static gnss_date_t	parseDate (nmea_span_t field)
	Decode a complete ddmmyy date field. More...

static gnss_validation_t	validateNavigation (nmea_span_t type, nmea_span_t fields)
	Validate standard fields before updating navigation data. More...

Static Public Member Functions inherited from Adafruit_NMEA
static nmea_sentence_t	validate (const char *data, size_t length)
	Validate a complete, length-bounded NMEA sentence without copying it. More...

static nmea_span_t	nextField (nmea_span_t &remaining)
	Return the next field and advance a bounded field cursor. More...

static nmea_decimal_t	parseDecimal (nmea_span_t field)
	Convert a complete field to an exact signed decimal value. More...

static nmea_number_status_t	validateDecimal (nmea_span_t field, bool allowNegative=true)
	Check an exact decimal without constructing its numeric value. More...

static size_t	buildCommand (char output, size_t capacity, const char body, size_t bodyLength)
	Build a checksummed command in caller-provided storage. More...

Detailed Description

Standard GNSS receiver and decoding shared by receiver implementations. Inherits bounded framing with caller-owned buffers and per-instance times. Position decoding is stateless: no fix is cached or merged across lines. Static decoding does not require receive storage. No heap or transport I/O.

Constructor & Destructor Documentation

◆ Adafruit_GNSS()

Adafruit_GNSS::Adafruit_GNSS	(	volatile char *	firstBuffer = `NULL`,
		volatile char *	secondBuffer = `NULL`,
		size_t	capacity = `0`
	)

Create a GNSS receiver using the shared bounded NMEA framer.

Parameters

firstBuffer	First caller-owned writable receive buffer.
secondBuffer	Second buffer, disjoint from the first.
capacity	Bytes per buffer, including NUL space.

Storage must outlive the receiver. The default or invalid storage disables feed() as described by Adafruit_NMEA; static decoding remains available. Supply incoming bytes and their timestamps with the inherited feed(). No position cache, transport, command handling, or allocation is added.

Member Function Documentation

◆ lastPosition()

gnss_position_t Adafruit_GNSS::lastPosition ( ) const

Decode the latest complete line into an independent position result.

Returns: Exact GGA/RMC/GLL measurements, or validation diagnostics.

Call after feed() reports a complete line, and synchronize with feed() if using interrupts. Each call validates and decodes the current line; it does not consume it. Before a line or after reset(), the result is INVALID_FRAME. Invalid completed lines replace earlier positions; proprietary replies and other sentences return UNSUPPORTED and remain accessible via lastSentence(). Partial/overflowing input preserves the previous complete line, just as the framer does. Use sentenceStartedAt() and sentenceReceivedAt() for this line. Returned values own their data and survive later input or reset().

◆ parseCoordinate()

gnss_coordinate_t Adafruit_GNSS::parseCoordinate	(	nmea_span_t	coordinate,
		nmea_span_t	hemisphere
	)

static

Decode a latitude or longitude field and its hemisphere.

Parameters

coordinate	DDMM[.fraction] latitude or DDDMM[.fraction] longitude.
hemisphere	Exactly one N/S for latitude or E/W for longitude.

Returns: Validated components and signed decimal degrees times 10000000.

Missing spans take precedence over empty spans, then malformed syntax, then range errors. Signs, spaces, exponents, and a bare decimal point are invalid. Minutes must be below 60; latitude is limited to 90 degrees and longitude to 180, with zero minutes at either boundary. Fractional minutes retain the first nine digits, padded with zeros; further digits are validated and truncated. degreesE7 is exact at its stated resolution, without rounding or intermediate floating-point arithmetic.

◆ formatCoordinate()

size_t Adafruit_GNSS::formatCoordinate	(	char *	output,
		size_t	capacity,
		const gnss_coordinate_t &	coordinate
	)

static

Format exact coordinate components as signed decimal degrees.

Parameters

output	Writable text buffer; must not overlap coordinate.
capacity	Buffer size including the NUL terminator. Use GNSS_COORDINATE_TEXT_SIZE to fit every valid coordinate.
coordinate	Validated components from parseCoordinate().

Returns: Characters written, excluding NUL, or zero for invalid components or insufficient storage. On failure output[0] is cleared when possible; no other output bytes are changed.

Writes exactly 11 fractional degree digits, truncated toward zero. This distinguishes every retained fractional-minute increment and introduces less than 0.00000000001 degree of formatting error (about 1.2 micrometers of latitude). Southern/western zero retains its minus sign. The components, not the lower-resolution degreesE7 member, supply the result.

Integer long division uses at most 32-bit arithmetic, with no heap or floating-point conversion. AVR output retains the same precision as other targets, regardless of NMEA_FLOAT_T or the platform's double size.

◆ parsePosition() [1/2]

gnss_position_t Adafruit_GNSS::parsePosition	(	nmea_span_t	type,
		nmea_span_t	fields
	)

static

Decode a GGA, RMC, or GLL position without retaining receiver state.

Parameters

type	Three-character sentence type without its talker prefix.
fields	Borrowed fields after the address comma and before '*'.

Returns: Independent values and validation diagnostics. Invalid or unsupported input returns no partially decoded measurements.

Call after validating the enclosing frame with Adafruit_NMEA::validate(). Input storage must remain readable and unchanged throughout the call. Validate all consumed navigation fields before returning measurements, including fields this result does not expose (such as altitude). Optional tails retain validateNavigation()'s existing behavior.

Populated coordinates retain all nine fractional-minute digits and can be passed directly to formatCoordinate(). Empty fields have EMPTY status; fields absent from this sentence type have MISSING status. The fix boolean is meaningful only with VALID fixStatus and does not imply populated coordinates. GGA quality is independent of RMC/GLL fix validity.

Time/date and exact position components belong only to this sentence. No timestamps, previous-fix merging, allocation, or floating-point conversion occur here. GSA and other sentence types are UNSUPPORTED by this decoder.

◆ parsePosition() [2/2]

gnss_position_t Adafruit_GNSS::parsePosition ( const nmea_sentence_t & sentence )

static

Route a validated standard NMEA sentence to the position decoder.

Parameters

sentence Unmodified view returned by validate() or lastSentence().

Returns: Independent values; INVALID_FRAME for non-VALID input, UNSUPPORTED for a valid frame outside the supported standard position sentences.

Keep the borrowed storage readable and unchanged throughout the call. Trust the supplied frame status; use validate() first for arbitrary text. A standard position address has two uppercase talker letters followed by GGA, RMC, or GLL. Any such talker is accepted except the proprietary 'P' prefix. Encapsulated '!' messages and proprietary addresses are not routed. No receiver-specific address whitelist or command handling is imposed on the underlying framer. Invalid/unsupported input returns no measurements.

◆ parseTime()

gnss_time_t Adafruit_GNSS::parseTime ( nmea_span_t field )

static

Decode a complete UTC hhmmss[.fraction] field.

Parameters

field Borrowed time field, with no terminator required.

Returns: Status and validated components, zeroed on failure.

Exactly six whole digits are required. A decimal point requires at least one fractional digit; all digits are checked, with the first three retained as milliseconds. Seconds may be 60 to represent a leap second. This checks field ranges, not whether a leap second occurred on a particular date.

◆ parseDate()

gnss_date_t Adafruit_GNSS::parseDate ( nmea_span_t field )

static

Decode a complete ddmmyy date field.

Parameters

field Borrowed six-digit date, with no terminator required.

Returns: Status and validated components, zeroed on failure.

Validates month lengths and February 29 using year modulo four. The NMEA field has no century; year 00 is treated as a leap year, as in 2000. Applications requiring a full year must resolve the century separately.

◆ validateNavigation()

gnss_validation_t Adafruit_GNSS::validateNavigation	(	nmea_span_t	type,
		nmea_span_t	fields
	)

static

Validate standard fields before updating navigation data.

Parameters

type	Three-character sentence type, without its talker prefix.
fields	Fields after the address comma and before the checksum.

Returns: Status and the first invalid or missing one-based field position.

Call after validating the enclosing NMEA frame. Checks the fields consumed by the existing GPS decoders: GGA through geoid separation, RMC through date, GLL through status, and GSA fix type and dilution values. Optional tails and the satellite IDs skipped by the GPS parser are left to their decoders. Empty fields are permitted, but a coordinate and its hemisphere must either both be empty or both be valid for the appropriate axis. Numeric fields must be complete representable decimals; speed, course, and dilution values cannot be negative. Fix quality and satellite count must fit uint8_t. Valid does not imply a position fix or populated fields. No receiver state changes, field arrays, or heap allocation are involved.

The documentation for this class was generated from the following files:

src/Adafruit_GNSS.h
src/Adafruit_GNSS.cpp

Public Member Functions

Static Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ Adafruit_GNSS()

Member Function Documentation

◆ lastPosition()

◆ parseCoordinate()

◆ formatCoordinate()

◆ parsePosition() [1/2]

◆ parsePosition() [2/2]

◆ parseTime()

◆ parseDate()

◆ validateNavigation()