Serial port interfacing with GPSes

11th Monday, 2012  |  Life at LAVA  |  no comments

GPSes are becoming commonplace, not just as the standalone devices we have in our cars, but perhaps even more often as a capability built into our smartphones. In the majority of cases, the data that those GPSes generate is used by and stored in the device itself, but occasionally people want to access that data in other ways. A typical instance is when someone wants to download waypoints, routes, or tracks for use in computer-based mapping software or to transfer data to another device. In such cases the appropriate GPS interface sometimes is RS-232 serial. For example, a number of Garmin GPSes have serial output:

eTrex H

Garmin eTrex GPS

Garmin eTrex GPS

eTrex Legend
eTrex Vista
eTrex Venture
eTrex Summit
Geko 301
Geko 201
Garmin GPS 35 TracPak Series (GPS 35 LVC, GPS 35 LVS, GPS 35 HVS, GPS 35 PC)

Additionally, at times a more specialized GPS is being used, and these GPSes often have RS-232 serial as their interfaces. Such GPSes may have greater sensitivity or a higher polling rate than usual. One example listed below is for rocketry, where taking telemetry readings every five seconds does not get the job done. Another, the syncboxRED, uses GPS signals for highly accurate timing.

high sensitivity GPS with RS-232

High sensitivity GPS with RS-232


GPS with RS-232 in rocket nosecone

Hackers have fun with data output from GPSes as well, and some of the links below reference such applications. LAVA PCI serial cards or USB-Serial Links are complementary to many of these GPS applications.

Modify any USB GPS to XDA Serial RS232, afternoon project:

Hacking Garmin etrex GPS: making your own cable to run from the proprietary connector to standard RS-232:

Another DIY cable for Garmin:

Garmin to serial interface

Garmin to serial interface

A connector source for those who want to make their own Garmin compatible cable:

CatTrack™ GPS to RS232 Adapter – Product information

Using the Holux GM-210 GPS for either RS-232 or TTL:

Another integration of the Holux GM-210 GPS:

High sensitivity GPS:

Rocketry application — high sample rate GPS: