WebSerialGPS

This is an offline web application using the WebSerial API for reading all of the GPS data from a GT-U7 NEO-6M GPS over Serial (USB). Although, in theory, this should work for any USB Serial GPS that uses NMEA GPGGA messages, but its usbVendorId will need to be added in serial.js. Selecting the device opens the serial port, then the data is read asyncronously. Pieces of the NMEA message are concatenated until a full sentence is captured. The data is then fed into its respective class from nmea.js where the sentence is parsed into useable and readable formats for display or other use.

How to Run

Connect the GPS via USB to your computer, then open the index.html file in a browser that supports the WebSerial API. NOTE, only Chromium based browsers support WebSerial at the time of writing this, so using Google Chrome, or some other modern Chromium browser is recommended. I have personally validated that this works in Chrome and Edge on Windows 11 and Ubuntu.
Once the page is open simply click Select Device, do that, and then click run.

NMEA GPS Serial Format Basics

Basic Standards:

• Messages start with '$' and end with '<CR><LF>'
• The first 2 chars after '$' is the talker
• The three chars after the talker is the type
• The information between the type and the '*' is the data
• The data is comma delimited
• The number after the '*' is the checksum for message validation
• The maximum message length is 82 characters

$GPGGA Message Example:

$GPGGA,075909.00,6451.53390,N,14749.78748,W,1,04,8.23,149.4,M,5.8,M,,*75
 
$GPGGA,         -- 00 - Message Type: GPGGA
075909.00,      -- 01 - Timestamp
6451.53390,     -- 02 - Latitude            -- 64  degrees, 51.53390 minutes
N,              -- 03 - Latitude Direction
14749.78748,    -- 04 - Longitude           -- 147 degrees, 49.78748 minutes
W,              -- 05 - Longitude Directions
1,              -- 06 - Fix Quality (0 is invalid, 1 is GPS, 2 is DGPS)
04,             -- 07 - Satellite Count
8.23,           -- 08 - Horizontal Dilution of Precision
149.4,          -- 09 - Altitude
M,              -- 10 - Altitude unit: meters
5.8,            -- 11 - Height of geoid above WGS84 ellipsoid
M,              -- 12 - Geoid height unit: meters
...,            -- 13 - Time since last DGPS update (can leave blank)
...             -- 14 - DGPS reference station id   (can leave blank)
*75             -- 14 - Checksum (same array position as last piece.)

Screenshot

Further Resources

• In-Depth NMEA GPS Sentence Information
• NMEA GPS Wikipedia
• Google's WebSerial API Docs
• Mozilla's WebSerial API Docs
• The GPS I Use