I have a Garmin Edge 520, and has a map called gmapbmap.img. Time ago I replaced this file (which Garmin provided) with a .img file I generated with QLandkarte GT, based on several .img tiles based on OpenStreetMap data. I gave that file the same name (gmapbmap.img) so that it was visible on my Edge 520 unit.Ok most likely your unit will only allow files with the names gmapsupp or gmapprom at any one time
I have also a file called gmapbmap.sum (that I didn't touch), plus another pair of files (gmaptz.img and gmaptz.sum) that I believe have to do with time zones but don't know their real function, and I didn't touch either.
I've tried JaVaWa Device Manager, and I see my unit and my two maps there:If you use Basecamp i suggest downloading this program for your operating system.
JaVaWa GPS-tools | JaVaWa Device Manager
Hook up your unit and close basecamp and run the program, it will scan your device and display your map files, ensure your maps have a basecamp image enabled next to them, close the program and start basecamp, your new map will now be displayed in basecamp.
As you see there is a lock meaning read-only and I can't change the visibility property or anything. Is there anything I can do?
I've also tried and copied the gmapbmap.img file in a USB thumb drive, inside a Garmin folder (as explained in this post). JaVaWa Device Manager sees that drive as a Garmin device and shows my map, and there I can set the property "Visible in BC" to "yes". However, although BaseCamp sees the USB drive as a Garmin device, I can't find that map anywhere in BaseCamp.
I use BaseCamp 4.7.0 for macOS.