N900 not recognizing microSDHC cards. (Back cover open)
 

I can't get my N900 to recognize SDHC cards. At first I thought I could actually have 3 bad microSDHC cards, but once I combed through the logs better I discovered its the back cover. It apparently is never detected as closed. I read in another thread that the cover is detected magnetically, and the inaccessibility of the drive is forced in the kernel. At this point, I dont see ANYthing in my back cover that looks like a metal or magnetic lead. Can someone post a high resolution picture of the inside of their cover? And even better, if you know where this switch is, please circle it so I can inspect my unit. Its brand new, so I need to get on asking for a replacement ASAP, im really hoping Ill just need a replacement back cover if anything..

-Sean-

Re: N900 not recognizing mircoSDHC cards. (Back cover open)
 

I think the magnet is inside the device, there's a shiny black metal part on the battery cover, near to the camera slider

Re: N900 not recognizing mircoSDHC cards. (Back cover open)
 

good and bad news. I was able to find the region of the N900 where the magnet should be by using an actual magnet. on my case, there is nothing there. Im off to radioshack to buy some magnetic tape...

Re: N900 not recognizing mircoSDHC cards. (Back cover open)
 

great news, I took the magnet from a pouch and was able to get it working. Im gonna upload some pics for anyone else with this problem shortly, hopefully nokia will just replace theback cover for me, but at least I can use my cards now.

Re: N900 not recognizing mircoSDHC cards. (Back cover open)
 

http://farm3.static.flickr.com/2490/...411cfc4d67.jpg

Hopefully this is helpfull to someone else. THe red circle on the cover appears to be what should fit in the gap, it does not even when the N900 is closed flush. The Red circle on the phone shows the magnet from a magnetic mouse pouch that I cut out and glued on the phone. It does not interfere with the closing of the top, and has had no other impact on the device. I can however as a side benefit, use the cards while the back is off. (WHy would anyone even do that? ;-p)

Re: N900 not recognizing mircoSDHC cards. (Back cover open)
 

Cause they want to check / format the card before tentatively putting the fragile feeling back cover back on?

I was going nuts since I knew my 8GB Sandisk worked, just pulled it out of the N82 and cleared it out!

Rebooting N900 now, seems you can't hotswap either! Hopefully it is seen when powered on again...

Re: N900 not recognizing mircoSDHC cards. (Back cover open)
 

Nope....no joy. Still not seeing my MicroSD card. Very odd. It looks like there is a magnet there on my back cover, wish I had a picture to confirm.

Going to have to find a magnet now and check, haha.

Re: N900 not recognizing mircoSDHC cards. (Back cover open)
 

:) Well, I blew 2 days on this, so I hope that this helps you. check your dmesg log it will tell you if the card is just corrupt, or if its the same magnetic problem. dmesg |grep mmc and look for the line about the cover open.

Re: N900 not recognizing mircoSDHC cards. (Back cover open)
 

Another thing to note is that if your card was encrypted on the other phone, the N900 will not recognize it even with a re-format on the other phone. You have to remove the encryption from it 1st.

Re: N900 not recognizing mircoSDHC cards. (Back cover open)
 

Or check dmesg when removing the back cover - you should see the following dmesg entries if your cover magnet is working correctly:

Re: N900 not recognizing mircoSDHC cards. (Back cover open)
 

slavikko guessed it!

I spent an hour last night trying to rememeber what my password was, LOL. After first trying to figure out why I couldn't read it from two PCs using three different interface methods but I knew it worked cause my N82 recognized it!! haha

Finally hit me, didn't I put a password on this so my GF couldn't look at it? :D

All good now, though have my eyes on an 16GB card.

Re: N900 not recognizing mircoSDHC cards. (Back cover open)
 

Is this related? read ossipena's post about halfway down...

http://talk.maemo.org/showthread.php?t=38868

some on this post think it is to do with the battery under the kickstand....

Re: N900 not recognizing mircoSDHC cards. (Back cover open)
 

I can definitely confirm it's a magnet which senses whether the backcover is on or off. i used the magnet on a generic case I bought for my N900. I was able to enable the SD card with the cover off by holding a weak magnet over the camera area.

So it looks like that magnet on the backcover is doing double duty. Keeping the kickstand snuggly held closed, and to tell the phone whether the backcover is on or off.

Additional note. There is a also a magnet and switch which are used to determine if the slide keyboard is open or not. It's located on the right side of the N900 well away from the backcover magnetic switch/sensor near camera. The use of these two magnet probably explain why there isn't a magnetic compass in the N900.

Re: N900 not recognizing microSDHC cards. (Back cover open)
 

I have some thing like this whit my n900: The magnet is in place but the cover is always recognized as open. If i hold a stronger magnet on this spot, it has no effect. I think the sensor is defect.
Is there a way to tell the kernel by software that the cover is closed? Some switch in /proc/ or so?

Thanks!

Re: N900 not recognizing microSDHC cards. (Back cover open)
 

There is an Xterminal command to tell if the status of the back cover is working or not. But can't remember

Re: N900 not recognizing microSDHC cards. (Back cover open)
 

Hey there!

Is there some way via Xterminal or hardware hack that you could fool the N900 has the back cover on when it actually isn't? Problem is i think the sensor is kaput...i mean the magnet on the cover is still there but even when i close it it still doesn't detect anything! So would it be possible to like force the phone to believe the cover is on?

In fairness there really is no point of the phone detecting whether it is on or not...no benefits what so ever!

Thanks!

Re: N900 not recognizing microSDHC cards. (Back cover open)
 

Automatically cleanly unmounting the micro SD card before that card is yanked from the phone seems beneficial to me. It makes me sad when I lose files to filesystem corruption.

Re: N900 not recognizing microSDHC cards. (Back cover open)
 

I had the same problem and i replaced the magnet with magnetic tape aswell. Here is something i noticed:

A magnet only works with the sensor when in a certain angle. Seems
the magnetic poles have to be aligned in a certain way. I had to cut several pieces from diffrent angles so that the sensor would work.

As a summary:
When trying to replace the magnet don't give up if it doesn't seem to work at first. Find the proper angle for the magnet to work with the sensor and then cut accordingly.

Re: N900 not recognizing microSDHC cards. (Back cover open)
 

Fair enough but surely a safely remove MMC option would suffice? I just think its caused more harm than good tbh

Re: N900 not recognizing microSDHC cards. (Back cover open)
 

I've the same issue, do you think the warranty covers this reparation?

Re: N900 not recognizing microSDHC cards. (Back cover open)
 

It Better Be..

Re: N900 not recognizing microSDHC cards. (Back cover open)
 

My back cover refuses to be detected no matter what I try. I've tried strong magnets, new back covers, and even pulled apart my phone to make sure everything was alright.

I think my sensor has failed.

Is there *any* software workaround for this issue? Does anyone know?

Re: N900 not recognizing microSDHC cards. (Back cover open)
 

Just a quick bump. I've pretty much confirmed that my back cover sensor has died.

Are there any software solutions, hacks, etc, to make the phone think that the back cover is on so I can use MicroSD cards again? Or am I going to have to pay to get my phone repaired?

Re: N900 not recognizing microSDHC cards. (Back cover open)
 

Any updates?
Is there a software fix?

Re: N900 not recognizing microSDHC cards. (Back cover open)
 

So...are there any software workarounds??

Reeeeally need this!!

Re: N900 not recognizing microSDHC cards. (Back cover open)
 

Quick reply...
I might be wrong...
gconftool-2 can found key
/system/osso/af/mmc-cover-open
which is false when back cover is closed and true when back cover is open.

This key is promptly set by sensor, so setting value of this GConf key manually may be in vain.

Re: N900 not recognizing microSDHC cards. (Back cover open)
 

Wikiwide i think you may have just opened up alot of doors!

Basically i was messing around with that key with gconftool. And i changed the value from true to false using :

This set the value from True to False, you can check it via :

I set it to false, but the MMC is still not detected. ALTHOUGH the camera now responds to the shutter being opened and closed.

If you go :

You'll find a list of Keys related to the back cover, camera and mmc. And their status will be displayed too!

IS IT POSSIBLE for anyone whos back cover works to test using the last code and display a status of the keys that are true and false? That would be really helpful, as that way we can enable/disable the right keys to truly fool the phone into thinking the back cover is on!

Thanks

Re: N900 not recognizing microSDHC cards. (Back cover open)
 

Place the SD card in your PC and check it for errors. The card detection can fail if it has disc errors, fix them and it may re-appear.

This happened to me, so I copied all my data off, deleted the corrupted file and re-formated. After copying all my data back the card appeared OK

Re: N900 not recognizing microSDHC cards. (Back cover open)
 

Done that, funnily enough the card is in my laptop right now and there are no problems/errors with it. Iv tried the phone with 3 different cards. Its that damn sensor inside the phone which detects the magnet on the back cover!

The best way to approach this would be a kernel patch which basically told the phone to disregard the back cover and just accept the MMC as always being there! I don't have enough experience with kernel hacking :(

Re: N900 not recognizing microSDHC cards. (Back cover open)
 

why dont u take it to repair?

Re: N900 not recognizing microSDHC cards. (Back cover open)
 

If I open the N900 file manager and using PuTTY on my PC I can
copy and past into PuTTY, I am able make my SD card appear with these commands in the N900 file manager

Code:

---

gconftool-2 -s -t bool /system/osso/af/internal-mmc-device-present true
gconftool-2 -s -t bool /system/osso/af/mmc-cover-open false
gconftool-2 -s -t bool /system/osso/af/internal-mmc-cover-open false
gconftool-2 -s -t bool /system/osso/af/mmc-device-present true

---

and disappear with these commands

Code:

---

gconftool-2 -s -t bool /system/osso/af/internal-mmc-device-present false
gconftool-2 -s -t bool /system/osso/af/mmc-cover-open true
gconftool-2 -s -t bool /system/osso/af/internal-mmc-cover-open true
gconftool-2 -s -t bool /system/osso/af/mmc-device-present false

---

Re: N900 not recognizing microSDHC cards. (Back cover open)
 

You probably could do it by typing it in the device itself, also, you could make a thingy with QueenBeecon to that runs the commands when you tap on them.

Re: N900 not recognizing microSDHC cards. (Back cover open)
 

1. Thanks a lot for thorough thinking.
2. Try to type it in X Terminal. Don't make people to install more additional software than necessary.
3. It could be saved into /usr/bin/microsdcard sh script so that instead of typing it over and over you would just execute this script(s).

Re: N900 not recognizing microSDHC cards. (Back cover open)
 

Nope, tried typing all that in, still doesnt see sd card! :confused:

Re: N900 not recognizing microSDHC cards. (Back cover open)
 

any solution in sight??. Took my phone to Nokia care centre but they wouldnt even look at it, there's no warranty for the the phone N900 in my country.

gosh!!!

Re: N900 not recognizing microSDHC cards. (Back cover open)
 

Same here. Tried all the gconf stuff, but still can't see the card :(.

Re: N900 not recognizing microSDHC cards. (Back cover open)
 

Hi!
I do it but I've this message:
Why I can't put it to false?

Can you help us please? :confused:

Re: N900 not recognizing microSDHC cards. (Back cover open)
 

Hello, if somebody can help us, please :(?

Re: N900 not recognizing microSDHC cards. (Back cover open)
 

Topic died over a month ago, but I've got the same problem and I'm just wondering if someone could trick the device to think that the back cover is closed?

Re: N900 not recognizing microSDHC cards. (Back cover open)
 

Sorry for having ignored this thread somehow. Here is the output for a working N900Hope it helps.