move other parsing functions in NMEA_parse.cpp
fix parseTime to be insensitive to number of decimal places and return bool.
add isEmpty() checks where needed.
reorder some declarations.
Not sure whether to make it float or double by default
/*************************************************************************
doubles and floats are identical on AVR processors like the UNO where space
is tight. doubles avoid the roundoff errors that led to the fixed point mods
in https://github.com/adafruit/Adafruit-GPS-Library/pull/13, provided the
processor supports actual doubles like the SAMD series with more storage. The
total penalty for going all double is under a few hundred bytes / instance or
0 bytes / instance on an UNO. This typedef allows a switch to lower precision
to save some storage if needed. A float carries 23 bits of fractional
resolution, giving a resolution of at least 9 significant digits, thus 6
significant digits in the decimal place of an angular value like latitude, and
thus a resolution on earth of at least 110 mm. That's closer than GPS will
hit, and closer than needed for navigation, so floats can be used to save a
little storage.
**************************************************************************/
typedef double
nmea_float_t; ///< the type of variables to use for floating point
Add check(), addChecksum(), tokenOnList(), and supporting variables. Modify parse() to use check() and test only on sentence name, e.g. GGA rather than $GPGGA. Uses strcmp() to eliminate the custom strStartsWith().
Detect time first character of NMEA sentence received and treat that as corresponding to GPS timestamp in the sentence. Still some latency, but less than using the end of the receipt.
Improve the time information by tracking from when a sentence is received, rather than when it is parsed. Track last valid Date, Time, and Fix separately.
Split out separate functions to parse fragments of sentences for time, lat, lon, fix. No functional changes. Reduces repetition and makes parsing process more readable. Will make adding new sentences less cumbersome. The difference tracking gets a little wonky stretching across function boundaries.
Added timeSinceFix() to return seconds since a valid fix was received. Modified $GPGGA parsing to also set fix = true/false based on quality.
Added more output sentences to Adafruit_GPS.h to facilittate testing with different sentences.
parse() Improves slightly on https://github.com/adafruit/Adafruit_GPS/pull/86 by indexing on the position of the $ and the * in the string instead of the beginning and the end of the string. Does not require sentence string have a particular termination, e.g. CRLF.
Parse start of checksum as character after first $.
Don't include '\n' or '\r' in GPS lines read. Previous code was putting '\r' at the end of each line and '\n' at the start before the $, thus having to start the checksum calculation at the third character. This may break the spacing on some code that prints out the NMEA lines.
Rick Sellens