maximum addressable memory for eTrex Legend HCx?

[+josh0322]

hello,

i am about to purchase a microsd card for my Legend HCx but I want to make sure I get the maximum amount of memory for the unit. I did some googling but didnt come up with anything. Does anyone have an idea of what the maximum would be?

[+StarBrand]

Generally speaking - stick with the 2GB cards. While I've read some users have had sucess with the 4GB HC cards - they don't all work in the unit. You can get the entire USA City Nav on a 2GB card

[eaparks]

While I've read some users have had sucess with the 4GB HC cards - they don't all work in the unit.

What the above quote refers to is that yes a 4Gb card works but 2 Gb of the card can not be used for loading maps onto. The last 2 Gb can be used only for storing Custom POIs and logging tracks onto the memory card, but these 2 applications take up such a very small amount of memory space that you are better off just staying with a good name brand 2Gb card such as a Kingston or Sandisk (not the Ultra II... won't work).

Edited December 4, 2008 by eaparks

[ubern000b]

Does anyone know if the 2gb memory card limit is a hardware limit imposed by the memory controller circuit used in te Garmin line? Is there a chance the limit is imposed in the firmware code and an update could raise the limit ? Or do the new high speed high capacity SD cards require a different memory controller. Too many questions...

 

I wonder if the Delorme uses the same memory controller chip? I'm sure Garmins/Magellans/Delormes share many common components. If they share the memory controller Garmins should be able to use the 32gb cards.

 

Someone familiar with the memory controller chip in the Garmin/Delorme products should chime in here.

 

Suppose I use a 4gb card anyway. How do I specify my POI and track data gets stored on the other half of a 4gb card ?

 

I'd really like to see the Garmins allow the use of

[+efflandt]

Does anyone know if the 2gb memory card limit is a hardware limit imposed by the memory controller circuit used in te Garmin line? Is there a chance the limit is imposed in the firmware code and an update could raise the limit ? Or do the new high speed high capacity SD cards require a different memory controller. Too many questions...

 

I am not really sure what the difference is between SD and SDHC, maybe a matter of having enough bits to access the higher capacity. For my Palm TX someone had to come up with a driver to handle SDHC. There is also a limitation of the number of map segments an eTrex can handle (2048 I think, which is about 1 GB of topo maps). For example I have a set of 2865 topo map segments (~1.5 GB) on microSD that worked fine w/SD adapter on my nuvi ( which has no memory size limit). While the central area worked fine on my eTrex, roads and topo farther out did not show up (just the basemap).

 

Not sure how limits kick in when 2 different mapsets are in the same file, because the each CityNavNT segment is an entire state, and the regional file I made combining that and topo maps of the same area is within any limits (779 maps or about 616 MB). For areas too large, it may take multiple files with only the current set named gmapsupp.img (rename files to use a different map group).

 

Just put all the maps you want on the card first and make sure they work. Then you can use the rest for other things.

[+user13371]

Does anyone know if the 2gb memory card limit is a hardware limit imposed by the memory controller circuit used in te Garmin line? ...

I'm sure Garmin knows

 

But taking a wag (and quoting Wikipedia's article on USB mass storage devices): "In cameras, MP3 players, and similar gadgets which must access the file system independently from an external host, the FAT filesystem is typically preferred by device manufacturers."

 

Which means... the GPS needs to be able to access the storage on the card, and other devices (such as your Windows or Mac computers) do also. So Garmin (as most other manufacturers) uses the most generic file system for the memory card, to allow the widest interoperability.

 

Even if the GPS can access a FAT32 formatted memory card (which would not have a 2GB limit on volume or file size), it's likely Garmin's own routines for reading map data were designed on and for older systems -- and may not know how to access the larger files and can't take full advantage of that.

 

An understandable limitation. After all, nobody will ever need more than 640K of memory, right?

Edited December 5, 2008 by lee_rimar

[roybassist]

In this post, annoyedone in the 76C(S)x Yahoo group says:

Garmin updated their firmware (i.e. card driver) to support SDHC cards

(that is those larger than 2GB) with v3.20. Prior firmware versions

will not recognize SDHC cards. 4GB cards work fine in the GPS with the

later firmware. There's no 2GB limit with them (I've verified this

using USB mass storage mode).

 

SHDC cards are formatted as FAT32 which has a 4GB filesize limit

(using Microsoft's implementation). Since Garmin's maps are saved in a

single file (gmapsupp.img in the Garmin folder) that limits the

mapset, using their current implementation, to 4GB not 2GB.

 

While I don't know for sure the exact reason for the 2GB mapset size

limit I suspect, as I've posted many times before, that their software

people used 'signed long' 32-bit variables rather than unsigned ones.

A signed 32-bit variable ranges from -2GB to +2GB so anything over 2GB

becomes negative. Changing this should be a fairly simple matter--I've

done it enough times myself (fixing other peoples code).

The firmware he refers to is for the 60/76 series, but my understanding is that current firmware for the eTrex units works similarly.

 

He describes himself as

a degreed embedded (hardware/software) engineer with over 20

years of experience

My experience in reading his posts since 2004 is that if he tells you something, you can trust it.

 

BTW, the 4 GB SDHC card in my 76CSx is formatted FAT32, and the unit accesses it as described:

a 4Gb card works but 2 Gb of the card can not be used for loading maps onto. The last 2 Gb can be used only for storing Custom POIs and logging tracks onto the memory card

[roybassist]

Suppose I use a 4gb card anyway. How do I specify my POI and track data gets stored on the other half of a 4gb card ?

You just tell the unit to log tracks to the card, and send custom POI to the unit using Garmin's POI Loader. The unit knows where to put them.

 

I am not familiar with the eTrex series, but on the 60/76 series you set up logging tracks to the card by selecting Data Card Setup on the Tracks page, then checking a box on that page. I expect the eTrex units work similarly.