My Garmin eTrex Vista Cx GPS has an expandable microSD memory card slot that can be used for storing maps. I have Garmin’s Topo maps as well as their City Navigator maps. The Topo maps are great to have when out exploring the backcountry, since they have topographical lines and various natural features that can make navigating the backcountry easier. Meanwhile, the City Navigator maps can be used to turn my little GPS into a fairly capable unit that can route me throughout the streets of the U.S. just like its big brother automobile units do. However, all of the expandability and flexibility comes at a cost- you have to know how to load maps onto the GPS!
For the most part, loading maps onto my Vista Cx is a pretty simple process based in Garmin’s MapSource program, but there are a few tricks and choices that I made for the process to suit my taste. I am going to describe those specifics here.
There is no limit that I know of to the maximum size of microSD card that the Garmin units can use, however, there is a limit of 2025 map segments that they can access. This is a seldom documented feature, but here is a reference that can fill you in some more. There are a total of 111 City Navigator map segments with a size of 1.5GB, but there are over 6600 Topo maps with a size of 1.8GB! I had considered buying a 4GB card to stash all my maps on once and for all until I learned of the 2025 map segment constraint. It’s a real bummer, but rather than mope over it, I decided to just make do with what I have and write down exactly how I’m using my 2GB card.
I decided to add all of the City Navigator maps and I chose a subset of the Western states Topos that got me up to 1897.6 MB with 1372 Maps. I suppose that if I come across a cheap 4GB card, I could add the rest of the western mountain states plus another few states of my choice before reaching the 2025 map limit. I have saved the map selection of these to Maps2GB.gdb, so I could always inspect exactly which regions I have loaded in the future.
If I decide to travel to a new location that I don’t already have maps for, I will load them to my older 512MB card and just swap the cards before/after the trip. That way, I won’t have to go through the hassle of completely reloading all the maps on the 2GB card.
Since I also use the microSD card to store recorded GPX tracks, I verified that the remaining space on the 2GB card would be sufficient. It turns out that 2 years of recorded tracks amounted to a whopping 5.5MB and there was over 34MB free on the 2GB card, so I don’t foresee any problems with running out of room to record GPX tracks!
Finally, it’s worth noting that to ensure the GPX tracks are actually recorded to the microSD card, you need to select the Track Menu, then Setup, then Data Card Setup, and finally make sure the checkbox is selected next to Log Track To Data Card.