eTrex 20 Adding Maps Question

[+GrnXnham]

Just got the eTrex 20. This is our 1st unit with both internal memory (1.7GB) and the slot for the micro sandisk card.

 

I have installed Garmin's City Navigator micro Sandisk card in the unit. I also installed a few free topo maps from File Depot using my Mac.

 

After doing so, I have a concern:

 

Is it possible to accidentally over-write the City Navigator card when adding additional maps? I noticed that these micro Sandisk cards don't have the locking option like the standard Sandisk cards do, so you can't prevent altering them.

 

When I added 4 geocaches to the unit, I placed three in the internal memory but I accidentally put one of them on the sandisk card. This geocache wasn't recognized by the unit. This tells me that the unit is capable of writing on top of Garmin's Navigator card. So when installing maps, is there a chance that it will wipe out the Navigator maps in order to replace them with any new maps I'm loading or is the unit somehow "smart" and knows to always place additional maps in the internal memory?

 

On my older GPSr units, every time I add maps, everything gets overwritten. I was just concerned that this could happen here and I'd lose City Navigator on the card.

[+dfx]

Is it possible to accidentally over-write the City Navigator card when adding additional maps?

 

Yes! This is because the default file name for new maps is hard coded to "gmapsupp.img" in the Garmin tools (and a lot of pre-made map files also use this name). Subsequently added maps would use the same file name and thus overwrite already installed ones. The solution is simple: Rename the file after adding a new map. Make sure you never have a file called gmapsupp.img installed anywhere.

Edited January 6, 2012 by dfx

[+GrnXnham]

Thanks for the response.

 

I checked and now I have a gmapsupp.img file on both the internal memory (maps I added) and the sandisk card (Navigator)

 

So you are saying that If I want to continually change the maps in the internal memory BUT keep the maps on the Sandisk card, I need to change the name of he gmapssupp.img file on the Sandisk card only?

 

OR...

 

If I don't want to alter either sets of maps but just add maps, I should alter the name on both the internal memory and the Sandisk card and then nothing gets overwritten?

 

But will the unit still recognize the maps as maps if I change the name?

Edited January 6, 2012 by GrnXnham

[+dfx]

My recommendation would be to always change the name of all gmapsupp.img files. You can use any file name you want as long as it ends in .img, like "city navigator.img", without affecting anything. Do this also after each time you add a new map, as the file name will be gmapsupp.img again and so it will be in danger of being overwritten at some point.

[Wintertime]

Yes! This is because the default file name for new maps is hard coded to "gmapsupp.img" in the Garmin tools (and a lot of pre-made map files also use this name). Subsequently added maps would use the same file name and thus overwrite already installed ones. The solution is simple: Rename the file after adding a new map.

DFX, I downloaded some files from File Depot and installed them on my eTrex under their own names, so there was never an issue of having to rename anything from "gmapsupp.img." Why would someone have to load them under that name and then rename them?

 

Patty

[+dfx]

Yes! This is because the default file name for new maps is hard coded to "gmapsupp.img" in the Garmin tools (and a lot of pre-made map files also use this name). Subsequently added maps would use the same file name and thus overwrite already installed ones. The solution is simple: Rename the file after adding a new map.

DFX, I downloaded some files from File Depot and installed them on my eTrex under their own names, so there was never an issue of having to rename anything from "gmapsupp.img." Why would someone have to load them under that name and then rename them?

 

 

Because when you use Garmin's MapInstall tool, the generated file will always have the name gmapsupp.img. You can change it only after it has been created by the tool.

[Wintertime]

DFX, I downloaded some files from File Depot and installed them on my eTrex under their own names, so there was never an issue of having to rename anything from "gmapsupp.img." Why would someone have to load them under that name and then rename them?

Because when you use Garmin's MapInstall tool, the generated file will always have the name gmapsupp.img. You can change it only after it has been created by the tool.

Oh, that must be frustrating! Glad I didn't have to do that.

[+GrnXnham]

Wow! That seems like a bad design on Garmin's part! I don't see any warnings in the manual about accidentally overwriting your Navigator card and then having to buy a new one. There wasn't anything about this included with the card either. Why didn't Garmin simply name the maps something else on the card to prevent an accidental overwrite?

 

Yet, it DIDN'T get overwritten when I added maps the 1st time. It somehow knew to add the maps to the internal memory instead of overwriting on the card? Maybe it automatically fills the internal memory 1st before overwriting the card?

Edited January 6, 2012 by GrnXnham

[+dfx]

Wow! That seems like a bad design on Garmin's part! I don't see any warnings in the manual about accidentally overwriting your Navigator card and then having to buy a new one. There wasn't anything about this included with the card either. Why didn't Garmin simply name the maps something else on the card to prevent an accidental overwrite?

If it's an SD card you bought from Garmin, isn't it write-protected or something? Or it might contain some hidden data that tells the tools not to overwrite it or something... I'm sure somebody else has more insight here.

 

Yet, it DIDN'T get overwritten when I added maps the 1st time. It somehow knew to add the maps to the internal memory instead of overwriting on the card? Maybe it automatically fills the internal memory 1st before overwriting the card?

Depends on how you installed it. With MapInstall, you can select internal storage or SD card as destination before you actually build the map, with the internal storage being the preselected default.

[+GrnXnham]

Wow! That seems like a bad design on Garmin's part! I don't see any warnings in the manual about accidentally overwriting your Navigator card and then having to buy a new one. There wasn't anything about this included with the card either. Why didn't Garmin simply name the maps something else on the card to prevent an accidental overwrite?

If it's an SD card you bought from Garmin, isn't it write-protected or something? Or it might contain some hidden data that tells the tools not to overwrite it or something... I'm sure somebody else has more insight here.

 

Yet, it DIDN'T get overwritten when I added maps the 1st time. It somehow knew to add the maps to the internal memory instead of overwriting on the card? Maybe it automatically fills the internal memory 1st before overwriting the card?

Depends on how you installed it. With MapInstall, you can select internal storage or SD card as destination before you actually build the map, with the internal storage being the preselected default.

 

Well I used MapInstall but it never gave me the option of selecting internal storage or the SD card as a destination. It just automatically put it on the internal storage. Maybe it has a way of detecting a Garmin City Navigator card and automatically ignores that as a storage option.

 

Yes, it's Garmin's SD card. I'm not sure if it's protected or not but I was able to change the name of the map file on it, just in case.

[+coggins]

Well I used MapInstall but it never gave me the option of selecting internal storage or the SD card as a destination. It just automatically put it on the internal storage. Maybe it has a way of detecting a Garmin City Navigator card and automatically ignores that as a storage option.

 

Yes, it's Garmin's SD card. I'm not sure if it's protected or not but I was able to change the name of the map file on it, just in case.

Just after opening it you get a choice where to install the maps, just like the following:

 

You must have missed it.