Instruction Manual

503 Series Industrial Grade CompactFlash Card Product Manual v2.1Cactus Technologies
®
52
CTWPROT™
6.3.
CTWPROT™ enables write protect function on the entire Cactus Technologies® card. This feature can
be activated in hardware or software. Hardware activation is by either a mechanical write protect
switch or a signal pin. On Cactus Technologies® -503-P1 and -503-WP1 CF Cards, pin 40 is used
as the Write Protect signal (pin 40 is currently unused in the CFA standard). If this pin is pulled low,
CTWPROT™ is enabled. Additionally, on -503-WP1 CF cards, there is an external Write Protect switch
which can also be used to enable the write protect function. The software write protect command
also has a password feature, which provides protection against unintentional modication of the write
protect status.
The hardware write protect mode is checked by the rmware only during power up time; any changes
to the write protect mode after that is ignored . When the write protect function is activated, all
subsequent Write commands that attempt to store data to the ash memory will be accepted but
no actual data will be written to ash; normal status will be returned to the host after the command
is completed. This is to prevent error condition in Operation Systems that cannot handle write
protection errors in ATA devices. The Cactus Technologies® card supports the ATA Request Sense
command (03H). This command is now obsolete but was used in earlier ATA standards for the card to
report extended error codes. If the host issues this command immediately following a write abort, the
command will complete and the Cactus Technologies® card will return an extended error code of 27H
in the Error register to indicate to the host that there is a write protect violation.
The CTWPROT™ command is a Vendor Specic Command with the following task le structure:
CTWPROT™ is a non data transfer command. The usage of the command code is as follows:
12d: enable write protect
13d: disable write protect
15d: enable permanent write protect; if this command is issued, the card/drive will
be in a permanent write protected state which cannot be disabled by issuing
command 13.
22d: enable write protect with password; the 32-bit password is specied in the
feature, sector number, cylinder low and high registers
23d: disable write protect with password; the same password used when enabling
write protect must be used to disable write protect
All other command codes are reserved for future use. The eect of the above
command codes in various states is shown below:
6.3.1. Command Structure
Register 7 6 5 4 3 2 1 0
Feature
Optional password byte 0
Sector Count
command code
Sector Number
Optional password byte 1
Cylinder Low
Optional password byte 2
Cylinder High
Optional password byte 3
Drive/Head
1 1 1 D 0 0 0 0
Command
C2h