OpenStreetMap is a global wiki map (think "Wikipedia for maps"). The wiki nerds have produced Garmin-compatible extracts that are available for free. Here's how to enjoy fresh free wiki maps on your GPS.
You will need:
- An expandable Garmin GPS (one with 'x' in its name or a fancy-pants new model like the ForeRunners or Colorado).
- A micro-SD memory card.
- Either a USB connector and Garmin driver software, or a card reader.
Step 1: Get Maps!
Map company Cloudmade do the whole world. Go to http://downloads.cloudmade.com/ and browse for the region you're interested in. Let's say we're flying to Barbados on holiday: http://downloads.cloudmade.com/north_america/barbados - download the IMG file and unzip it.
The OpenStreetMap project has their own download page here: http://wiki.openstreetmap.org/wiki/OSM_Map_On_Garmin. There are lots to choose from including different regions, levels of detail, and styling. Fill your boots, it's all free.
My own Garmin map, which is a routable UK & Eire with extra contour lines (thanks NASA!) updated weekly, is here: http://ravenfamily.org/andyg/maps.
When you've downloaded your map, you should have one file with a .IMG extension.
Step 2: Using an SD Card
Step 3: Connecting via USB
Ready? Right. Go to the menu screen, choose Setup, then choose Interface. Click the big "USB Mass Storage" button and your GPS is now a USB drive on your computer. Nifty, huh?
Step 4: Copy the map to the GPS
The map is a file called GMAPSUPP.IMG and it lives in the \Garmin folder. You can ignore any other files that may be present.
So the order of ceremony is something like this:
1: Copy the existing GMAPSUPP, your old map, to your PC so you don't lose it. Stick it in a folder with a sensible name!
2: Delete the GMAPSUPP on the SD card / mounted GPS.
3: Copy your new map IMG up to the card/GPS's \Garmin folder.
4: If it's not called GMAPSUPP.IMG, rename it now.
Finally, restart your GPS and your map will be ready for adventure!