Fun with large SD Cards

This week I have been experimenting with an Adata 8gb class 6 SDHC card. My original idea was to put everything on the card. With the card in the TomTom it will only format it as a 4GB card. This seems to confirm the earlier statement that while the 720 can read a larger card it can only write to 4gb. So onto the tests:

1) Formated the card FAT32 8gb in a card reader. Copied all the files and mp3's to the card. Wiped all data from the internal memory and booted the 720 from the card. The 720 came up fine, but running this way it did not save any setting changes and on shutdown it would immediately reboot (a sign that it cannot update it's config files).

2) My next though was to format it as a 4gb card while in the 720, not the card reader (with the idea it can write to whatever it formats). I loaded the map and program files onto the card and the mp3's onto the internal memory. This would leave me with 2gb free on the card for more music, maps or POI's. While I can now save changes, I still have the reboot on shutdown issue so it is still having problems writing to at least one file.

3) (next test, yet to be tried) So my final thought on how best to use the card is to put the map and program back onto the internal memory and format the card as 8gb for just mp3's. While not ideal since the internal memory will be almost all the way full it should get past the issue of the 720 not being able to consistently write to the large card.

Now my question to the group, has anyone been able to run with a +4gb card holding anything other than music? If so what do you run on the card and what on internal memory?

It would also be a nice firmware addition to allow both read and write to the larger cards. I would expect since they can be read that the hardware itself would work and the limitation is software.

I can confirm a 4GB HCSD Sandisk card works in my 720.

I'm running off of it primarily, with my map and all data.

SanDisk 8 GB, Extreme III (SDHC)

I am using a SanDisk 8 GB, Extreme III (SDHC) on my 720.

Currently I am only using it for MP3s.

Works just fine.

As I want to and the UK version of the computer voice, I assume I will need to add it onto the card, as the internal memory is pretty full.

Nicholb:

Another thing to try is placing just the MAPS on the card in the appropriate folder. See if that may work - I don't recall if the TT writes much to the map folder(s) when it is doing things. It may only write to the root folder and some others but not do any writing to the maps?????

I guess you can look at the folders in internal memory and see which ones have any new files or files created/modified and if nothing in some of those changes, copy those folders over.

It sounds as if you are willing to experiment. I finally returned an 8gig card since it had similar write problems on my 920

Tonight I am giving the 4gb card I have for my camera another try (could not get it to read last time). This time I was able to format it in the 720. So I have the music on internal and everything else on the card. That leaves me 2gb.This looks like it is working so far. Now to find the 920 POI file and load that. The main goal I have it to get free space on the map/program drive so updates are not a problem.

Another interesting thing is my camera (Panasonic FZ50) is only supose to be able to handle a 4GB card (have not seen anyone on the camera forums post otherwise). It seems perfectly happy with the 8gb card, seeing the full size. So all works out good.

It looks like my last config is working fine. So it seems the largest total memory you can fully read/write access is 6gb (2 internal, 4 external). My thought on putting the program and map on the card is to give Home only one place it has to look for updates. This avoids having to make it check both the card and the internal memory when you connect up. It allows maximum space for the maps and program so no deleting things just to allow an update to install. It also gives you the greatest free space flexibility since music files will be read off both internal and external memory at the same time. If I want more than 2gb of music I can put some on the card.
I did also get the 920 POI files loaded so I am quite happy with the current setup. So unless there is a firmware update in the future to allow bigger cards I think I'll go with this.

I have maps and mp3's on an 8gb card. Works just fine, poi/destinations/etc are writen without hassle.

There's nothing special with the card, 8gb, shdc forwarted vfat32.

One thing I noticed when playing with the 8gb card is that whenever I had it in the 720 and was browsing the contents through windows there were some directories I could not open. If I tried, I lost all access to the card until I restarted the 720. These same directories would read fine from a card reader. They also were not the same directories each time I loaded up the card. My initial conclusion is that the 720 seems to be only able to read/write access the first 4gb of the card. Anything that happens to be on the second half can only be read. This may explain some of the inconsistent results people have reported. When you load the card if you happen to have all the files you need to write to in the area the 720 can fully access the card works fine. If one of those files are on a sector the 720 cannot write to, the card causes problems. Also due to the way data is written you would not necessarily have to have more than 4gb of data written to the card for it to place some of it on the second half.

The other explanation could be that there are differences in the cards. This I would not expect. They would all have to follow the SDHC standards and other than speed should have identical access properties. This seems to fit the fact that the 8gb card I have works fine in the card reader and my camera.

One last thought is that it could be a difference in the 720's. Perhaps newer ones are able to read/write to larger cards.

F22 said:

Nicholb:

Another thing to try is placing just the MAPS on the card in the appropriate folder. See if that may work - I don't recall if the TT writes much to the map folder(s) when it is doing things. It may only write to the root folder and some others but not do any writing to the maps?????

(rest deleted for brevity)

Click to expand...

There are some files that are written to the map folder amongst which: mapsettings.cfg containing your home location and favorites accessed and updated by TT system; a number of small files that get updated with MapShare when in Home. You can see the latter when comparing your map folder with your last backup after a MapShare update.

I normally do my TT system writing tests by doing screendumps which I later check with IrfanView.

I expect 720 and 920 to behave similarly as they use the same hardware for the USB and memory access. It is done with a Samsung S3C2443 which is an integrated chipset with cpu, controllers for memory IO, DMA, display, USB, clock etc. The newer x30 TT models use the same chipset.

I am sure glad I do not have any of your problems with sd cards. Because the 910 has a 20gb hard drive and I do not have to worry about running out of any room for anything!

Free Memory Card Formatting Software

Have you tried formatting your card with this free software from Panasonic? It's my understanding it should allow you to use whatever size you want. If you try it, let me know how it works out. I ordered a 16GB card that I haven't gotten yet. Also, there's other threads with elaborate instructions to get this working.

http://panasonic.jp/support/global/cs/sd/download/sd_formatter.html

Since I have a Panasonic camera I have used that program before, but did not try it for the 8gb card I was using on the TomTom. I probably won't try it since I now have everything working the way I want. I would not think that it would help since it apears to be a hardware limitation on the writes, but I would be interested to hear your results when you get the 16gb card.

Two things to watch for if the TomTom is having problems. One it will restart on shutdown if it cannot update a file. The other is if you have the card in the TomTom and are connected via the USB cable, there will be folders you cannot open.

Sd Card

I have a Go730 and use a 16GB SDHC card flawlessly with thousands of mp3's on it....of course thanks to forum members i used a card reader and windows explorer to do so

Crazyfamily said:

I have a Go730 and use a 16GB SDHC card flawlessly with thousands of mp3's on it....of course thanks to forum members i used a card reader and windows explorer to do so

Click to expand...

You no longer need a card reader to write to cards above 4GB. The new navcore 8.3 has addressed that limitation. Plus, that post you responded is pretty old as well. You revived an old thread