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Garmin Foretrex 201 GPS


Garmin Foretrex 201 The name field must be composed of max 6 characters, choosen among uppercase letters, digits, space, plus, minus, or underscore. That is the name must match the following regular expression: [ 0-9A-Z_+-]{1,6}

The sym field describe the symbol displayed by the GPS for the waypoint. It must be one of the following string:

Flag, Residence, Car, Campground, Waypoint, Hunting Area, Geocache, Geocache Found, Boat Ramp, Fishing Area, Marina, Shipwreck, Swimming Area, Skiing Area, Trail Head, Skull and Crossbones, Medical Facility, Telephone, Restroom, Information, Park, Scenic Area, Picnic Area, Gas Station, Restaurant, Lodging, Bank, Golf Course, Building, Airport, Parachute Area.

Saving a track

Beware of the save track function of the GPS, which recompute the track to save space, but loosing some points.

Real example: we have captured three track segments; the GPS now contains three distinct tracks: ACTIVE LOG, ACTIVE LOG #2 and ACTIVE LOG #3, each containing a single track segment. Saving in a new track, all the segments are collapsed in single track segment contained in a single new track, saved with the given name. The number of points passed from (273 + 161 + 740) = 1174 to a total of 401 points, loosing in fact several details. Timestamp of track points are preserved, but the breaks between original track segments are lost; in place of the break, now you can just notice two points separed by a longer time interval.

Track resolution

Changing from MEDIUM to HIGH resolution on sampling tracks, it seems that only a 4% more points are saved: this is a sample riding the same route forward and backward:

km 5.84 5.83
time 8:00 7:47
km/h 43.80 44.94
Points 99 103

Serial Cable

Garmin GPS unit Pin Name Garmin GPS unit Pin Number Direction PC Pin Number PC Pin Name

Here it is the contacts pinout on the back of the ForeTrex:

Acquisto accessori

Connettore eTrex

Garmin eTrex pinout

1 Power (+)
2 Rx data
3 Tx data
4 GND (-)

Connector for Garmin eTrex

Upload OpenStreetMap route to the Garmin

There is a fantastic service offered by just choose a starting and an ending point on the map, add waypoints if required, select pedestrian or car routing. Then download the GPX track that you can upload to the Garmin Foretrex.

I used a serial-to-USB adapter, with gpsbabel on GNU/Linux, this is the command line:

gpsbabel -t -i gpx -f Track_cerchiaia-pacini.gpx -o garmin -F /dev/ttyUSB0

Be sure you put the GPS in Garmin mode: SetupSet interfaceI/O Format Garmin.

Upload Google Maps route to the Garmin

Add the following code as a link into your FireFox bookmarks (call it GMapToGPX).


A copy of the JavaScript code is here: gmaptogpx.js.

Open Google Maps and obtain driving directions.

Click on the bookmark.

It will appear a window. If you want all the points, get the data as a trak. Copy and paste in a document.

You need to split in files of max 500 trackpoints each, because saved tracks have that limit on the Gramin.

doc/appunti/hardware/garmin_foretrex_201.txt · Last modified: 2018/04/28 12:15 by niccolo