X76F041 Datasheet, PDF (12/21 Pages) Xicor Inc. – PASS TM SecureFlash

X76F041
Configuration of Passwords
The sequence in figure 14 will change (program) the
write, read and configuration passwords. The program-
ming of passwords is done twice prior to the nonvolatile
write cycle in order to verify that the new password is
consistent. After the eight bytes are entered in the sec-
ond pass, a comparison takes place. A mismatch will
cause the part to reset and enter into the standby mode
and a “no ACK” will be issued.
There is no way to read the Read/Write/Configuration
passwords.
Program Configuration Registers
This mode allows programming of the five configuration/
control registers using the configuration password. The
retry counter must be programmed with a value less than
the retry register. If it is programmed with a value larger
than the retry register there will be a wrap around.
Read Configuration Registers
This mode allows reading of the 5 configuration/control
registers with the configuration password. It may be use-
ful for monitoring purposes.
Figure 13. Configuration Random Read
SDA LINE
IF PASSWORD
MATCH THEN
FIRST BYTE
S
BLOCK ADDRESS
T
A
R
T
C
M
D
A
X
A
X
A
X
A
X
A
8
AAAAAAAA
76543210
CONFIGURATION
PASSWORD 7
S
A
A
A
C
C
C
K
K
K
CONFIGURATION
PASSWORD 0
WAIT
tWC/ACK POLLING
A
A
C
C
K
K
SECURE
READ SETUP
S
T
A
R ^{A A A AAA A A}
T ^{7 6 5 432 1 0}
DATA 0
S
T
A
RAAAAAAAA
T76543210
S
T
DATA 1
O
P
XXXXXXXXS
S
S
A
A
A
C
C
C
K
K
K
7002 ILL F16.3
Figure 14. Program Passwords
SDA LINE
IF PASSWORD
MATCH THEN
S
T
A
R
T
C
M
D
A
X
A
X
A
X
A
X
A
8
READ/WRITE/
CONFIGURATION
INSTRUCTION
OLD
PASSWORD 7
S
A
C
K
NEW
PASSWORD 7
A
A
C
C
K
K
NEW
PASSWORD 0
OLD
PASSWORD 0
A
C
K
NEW
PASSWORD 7
WAIT
tWC/ACK POLLING
NEW
PASSWORD 0
S
T
O
P _WAIT
S ^tWC
A
A
A
A
C
C
C
C
K
K
K
K
A
A
C
C
K
K
7002 ILL F17.1
12