User_conf, User_lock, User_passwd – Maxim Integrated MAX15303 PMBus Command Set User Manual
Page 40: Security_level
MAX15303 PMBus Command Set User’s Guide
Page 40 of 52
USER_CONF
memory value of
, then the MAX15303 will ignore attempts to write data to that
command.
Note that setting a bit for a read-only PMBus command or send-byte PMBus command has no effect,
regardless of SECURITY_LEVEL. Likewise, read operations for any PMBus command are never blocked
on the basis of USER_CONF and SECURITY_LEVEL.
The 32 data bytes for USER_CONF are saved in flash memory as a unique, single instance (i.e., not as
part of the USER, DEFAULT, or MAXIM PMBus command stores.) The data is written to flash every
time the USER_CONF command data is written to the MAX15303.
Wait at least 350ms for execution after sending the USER_CONF command before sending additional
PMBus commands.
USER_LOCK
Reference:
Maxim Specific
Lockable:
Yes
Command Code:
0xE4
Format:
Direct
Data Bytes:
2
Units:
N/A
Transfer:
Read Word
Factory Value:
0x0000
Description/Notes:
The USER_LOCK command contains the password value for the “user” PMBus command security
level. If the working-memory value of
matches the working-memory value of
USER_LOCK, the
value is set to 1, and any PMBus commands flagged in
are unlocked for write operations.
Note that SECURITY_LEVEL must be set to 1 before a new value can be written to USER_LOCK.
The value of USER_LOCK can be stored in both the USER and DEFAULT nonvolatile PMBus memory
with separate and distinct values – this should be taken into account when setting up command
security.
USER_PASSWD
Reference:
Maxim Specific
Lockable:
Yes
Command Code:
0xE5
Format:
Direct
Data Bytes:
2
Units:
N/A
Transfer:
Read/Write Word
Factory Value:
N/A
Description/Notes:
The USER_PASSWD command is the “key” or password-attempt command used to unlock the “user”
security level. If the working-memory value of USER_PASSWD matches the working-memory value of
, the
value is set to 1, and any PMBus commands flagged in
are unlocked for write operations.
The value of USER_PASSWD is only retained in working memory and cannot be stored.