How to disable Write Protection of a SD Card?

[enturk]

Posted on December 05, 2011 at 14:37

Hi Everbody,

I try to disable the write protection of a SD card? How can i use CMD29 to disable the write protect?

[enturk]

Posted on December 05, 2011 at 14:38

Hi,

I use stm32f205, sdio 4-bit comm. 

[infoinfo989]

Posted on December 05, 2011 at 21:49

The format of the CMD29 command is described in the SD card spec, which is a free download from the SD Card Association website.

Note this command has nothing to do with the write-protect switch on the card (which is not connected internally to the card). Also the spec points out that SDHC and SDXC cards do not support the CMD29 command.

[enturk]

Posted on December 07, 2011 at 12:39

Hi Frank,

Thanks alot. I try to write long file Kingston SD card but failed. Some part of file is incorrect in SD card ( Kingston ). When I use another SD card ( Which is Sandisk or Syrox ), it writes long size data into SD card correctly. I face problems with Kingston SD cards. Doest it have different electrical specs or clock?Best Regards.

[infoinfo989]

Posted on December 07, 2011 at 16:54

You're welcome.

I'm not aware of any electrical differences with Kingston cards. I have a Kingston class 10 16 GB SDHC card and have noticed it's pretty slow (compared to my other cards) for reading, but that's not an electrical issue; that's just how its internal controller functions. What speed is your external SDIO clock running at? If you think you might have a timing issue, you can try slowing down your SDIO clock and see if that helps. Is your card connected directly to your processor, or do you have a level converter or some other logic between the card and STM32? ~~~~~~~~~

http://www.frankvh.com/stm32-information.html

[rosarium]

Posted on December 08, 2011 at 09:22

which file system you are using??

[enturk]

Posted on December 09, 2011 at 08:02

Hi,

I use Chan Fat file system, FAT32. 

[enturk]

Posted on December 09, 2011 at 08:05

Hi Frank,

I store alot of music files (.mp3) to my SD card ( Kingston ) in my PC. When i plug the SD card to my Music player ( on my car ), There is only half of the music files on SD card. I mean that these Kingston cards have problem. Thanks alot.

[infoinfo989]

Posted on December 09, 2011 at 17:03

I have a Kingston 16 GB ''Class 10'' card. That's what it says on the packaging and on the label. It was purchased from a major retailer (not some ebay special). But it's the slowest card in my collection. According to its internal registers (the 512-bit card status), it's actually a Class 4. and I have other class-4 cards which are faster than this one. So yes, I certainly agree with you, Kingston does not appear to be a quality brand. Having said that, we don't always get to choose which cards customers stick in our products (maybe you have that control but we don't), so we have to do the best we can.

[Tesla DeLorean]

Posted on December 09, 2011 at 18:16

Having said that, we don't always get to choose which cards customers stick in our products.

Frank that is SO TRUE, my experience is they will even cram in things which should not physically fit. Expect anything, fail gracefully.