# CARD_UnlockBackup

## Syntax

  `#include <nitro/card.h>`
  `void CARD_UnlockBackup(u16 lock_id);`

## Arguments

lock_id | ID used for locking a card

## Return Values

None.

## Description

Unlocks the access bus to the CARD backup device.
If another module (with another ID) is already waiting for the bus to unlock, access rights go to the waiting module. If the specified ID refers to a device that is currently locked, the bus is unlocked, and control is returned.
If the ID refers to a device that is not currently locked, a warning message is output, and the `OS_Panic` function forcibly stops the process.

## Note

- All functions that access a CARD backup device must first lock the access bus. You cannot access a CARD ROM device and a backup device simultaneously. While one bus is locked, other bus locks are forced to wait.
- The access bus cannot be unlocked while the backup device is executing an asynchronous process. If you call this function at such a time, the CARD library will force the function to wait until after the asynchronous process has completed to unlock the bus.

## See Also

`OS_UnlockCard`
`OS_UnlockCartridge`
`CARD_LockBackup`

## Revision History

2009/01/30 Corrected the description of the behavior for invalid lock ID.
2007/04/04 Added text noting that the bus cannot be unlocked during the backup process.
2004/09/06 Corrected the description of the prototype.
2004/08/31 Added text noting that function always succeeds.
2004/07/23 Changed the lock ID type from `u32` to `u16`.
2004/07/13 Made additions regarding exclusive control of CARD ROM device and backup device.
2004/07/10 Initial version.

CONFIDENTIAL