Thanks for your responses my friends,

I use only Sandisk cards (I use microSD which belongs to Version 2.00 
and higer) but that seems not to work. Also I can't find any software 
for WinXP to do a software lock based on password for those SD cards, 
just to make sure that it works.

It's realy strange that there is almost no information about it except 
in the Sandisk documentation (which is very limited to text only).

Hope someone can tell me more about it.

Hi Termite,

I already have done that, that's how I managed to read/write SDHC cards.
That's why it's a real problem to me, because using the documentation is 
the only information I have about lock/unlock the SD card. It's a bit 
confusing...

Please if someone else implement the lock/unlock piece, please share 
with me the source, or at least what things should I do. Cause it 
doesn't work accoording to the Simplify spec doc from Sandisk.

Thank you.

Thanks Termite,

Ok, there can be several reasons why it couldn't work.
Like you said, the length of datablok. I just used 4 bytes, one is for 
mode, one is for passwordlen and two for the password. I used as 
password: 0xAAAA.
But I also include 2 bytes of CRC16 value, but set datablock length is 
just 4 bytes. I get no error, the response of CMD42 = 
0b00000000000000000000100100000000
When I ask the card for the card-status I get: 
0b00000000000000000000110100000000

Another reason could be that I switched off CRC check at the very 
beginning, while CMD42 uses CRC16 on the dataline.

Hello,

Has anyone tried the software lock/unlock command (CMD42) succesfully?
Because I don't, and I'm so tired and stressed of waisting my boss's 
time.
I've tried everything, but that damned command is not working for me.
I realy hope someone can give me a golden tip.

Thank you.

Hello guys,

I recently tried to get lock/unlock the SD card again, but with no 
succes.
So is there anybody who got the lock/unlock working for the SD card?

I've searched the whole web, read SD documentation again and again with 
another guy from my work, but I still can't manage to get it work. Also 
it seems there is nobody on this planet who manages to lock an SD card 
with a password and than unlock it again. Even Linux or Windows don't 
have the possibility to protect the SD card with lock command. Also 
there is no software that can do that, even commercial ones.

So I seriously doubt wether CMD42 (lock/unlock) is actually working. So 
I dare to challenge really good embedded experts that they can't get the 
CMD42 working. So experts, prove me I'm totally wrong, I really offer 
you to disgrace me as much as you can.

Thank you.

HI
I tested the lock/unlock function ,and it worked.
I used to want to help you ,but I'am an Chinese and I don't understand 
German-language, I tryed to login, but don't know how to login.
Today while I try again, I find it's in English, my English is poor, but 
I know some simple words.
At first you should check out whether your SD card support lock/unlock. 
I have three SD cards tested, two from panasonic(32MB) and one from 
kingston(2GB),it seems the old panasonic card does not support this 
function, and the new kongston SD works well.
You can use a mobile phone to check it. I don't know why Windows doesn't 
support, but my Linux phone(MOTO E6)supports. If the SD card support, 
you would see a "password protection".
I use the MOTO E6 to lock my card, and use STM32F103VBT6 to unlock, then 
use STM32 to lock and E6 to unlock, both works well.
I use the SPI mode.
If I cound help you, please email chairang<at>126.com