Eggfinder LCD RX logger

[waltr]

Build an Eggfinder LCD RX with GPS plus a couple on Mini TX recently. It worked great to find my rockets in the corn fields.
Wanted to have a GPS 3D track so added an Open Logger.
The Open Logger is a small board with a micro SD card holder (originally from SparkFun but available from many sources). It has a simple Async serial input that writes any data coming in the the SD card.

The Eggfinder LCD board has a 4-pin header with 3.3V, gnd, TDX & RDX. The LCD outputs the remote GPS data in NMEA format at 9600 Baud on the RDX pin. Cris designed this to use a Blue Tooth module to send the GPS data to a moble device for GPS tracking. I don't like bothering with lap tops at the field so simply want to log the data for later evaluation.

First photo show the Open logger mounted inside the LCD RX case with double sided foam tape. The SD card holder is close to the case wall. Next photo shows the slot cut in the case with the edge of the SD card showing. The card is recessed so can not get bumped and released (push to release). I do need a small probe (screw driver) to seat the card and to release it.

Last photo is the connection from logger to LCD board.

When home pull the SD card out and connect to PC. Copy the "LOG0000x.txt" file to PC then rename with a .nmea extension (Windows will give a warning, click ok). Open Google Earth (or your favorite 3D map program) then import the .nmea file. The 3D plot show up.

 

[Worsaer]

The same concept works on the transmitter, with the benefit of not losing data when reception is interrupted. Think of it as an onboard flight recorder.

 

[waltr]

Yes, could also connect Open Logger directly to Mini TX but this take more room in rocket and IF can not find it on first try there is a record of the flight to analyze.
This can be very helpful if it drifts a long way and go behind a hill where reception is lost before landing and can't pick up the 915MHz link again. Have read on this forum of this happening and post analysis of the GPS data got them close enough to find the rocket.

Many ways to do this all with pros and cons.