ISSUE 4.2 : November 1998
PUMA 2E1000-70/90/12
Software Data Protection
Softwarecontrolleddataprotection,onceenabled by theuser,necessitatestheuseofasoftwarealgorithmbefore
any Write can be performed. To enable this feature a special sequence of 3 Writes to 3 specific addresses must
be performed, and must be reused for each subsequent Write cycle. Once set the data protection remains
operational until it is disabled by using a second algorithm; power transitions will not reset this feature.
Note that the PUMA 2E1000 is supplied with the Software data Protection feature disabled.
The algorithms to enable and disable the protection are shown below:
SDP Enable
SDP Disable
LOAD DATA AA
TO
LOAD DATA AA
TO
ADDRESS 5555
ADDRESS 5555
LOAD DATA 55
TO
LOAD DATA 55
TO
ADDRESS 2AAA
ADDRESS 2AAA
LOAD DATA A0
TO
LOAD DATA 80
TO
ADDRESS 5555
ADDRESS 5555
WRITES
ENABLED
(2)
LOAD DATA AA
TO
ADDRESS 5555
LOAD DATA XX
TO
ANY ADDRESS
(4)
LOAD DATA 55
TO
ADDRESS2AAA
LOAD LAST BYTE/
WORD TO
LAST ADDRESS
ENTER DATA
PROTECT
STATE
LOAD DATA 20
TO
ADDRESS 5555
Once initiated, the enable sequence of
write operations should not be interrupted
EXIT DATA
PROTECT
STATE
(3)
LOAD DATA XX
TO
ANY ADDRESS
(4)
Notes : (1) Data D7 - D0 (hex); Address A14 - A0 (hex).
(2) Write Protect Mode will be activated at end of
Write even if no other data is loaded.
LOAD LAST BYTE/
WORD TO
LAST ADDRESS
(3) Write protect state will be disabled at end of
write period even if no other data is loaded.
(4) 1 to 64 bytes/words of data can be loaded.
Note: Load Data above represents 8 bit mode. For 16 or 32 bit mode, place the load data in the 2 bytes or
all 4 bytes on the data lines, respectively. Eg/ 8 bit load data = 55HEX, 16 bit load data = 5555HEX
.
All software write commands must obey the Page Write timing specifications.
TheprocessofdisablingtheDataProtectionmodeisverysimilartothatdescribedforenable,except6bytes/words
must be loaded to specific locations in the EEPROM as shown.
Noteheretheuseoftheword'load'todescribeenablinganddisablingtheprotectionmodesinpreferenceto'write'.
Although it may seem that if the Write command sequence is performed to enable protection then the three bytes/
words at those addresses will be overwritten with AA,55,A0, this is not the case.
10
MOSAIC [ MOSAIC ]
