MIC3000 Datasheet, PDF (49/68 Pages) Micrel Semiconductor – SFP Management IC

MIC3000
Micrel
OEM Password Entry (OEMPW)
D[7]
Read/write
D[6]
Read/write
D[5]
Read/write
D[4]
Read/write
D[3]
D[2]
Read/write Read/write
D[1]
D[0]
Read/write Read/write
Default Value
0000 0000_b = 00_h (reset to zero at power-on)
Serial Address
A2_h = 1010001_b
Byte Address
120 – 123 = 78_h - 7B_h (MSB is 7B_h)
This four-byte field is for entry of the password required to access the OEM area of the MIC3000’s memory and
registers. A valid OEM password will also permit access to the user areas of memory. The byte at address 123 (7B_h) is
the most significant byte. This field is compared to the four-byte OEMPWSET field at serial address A6h, bytes 12 to
15. If the two fields match, access is allowed to the OEM areas of the MIC3000 non-volatile memory at serial ad-
dresses A4_h and A6_h. The OEM password is set by writing the new value into OEMPWSET. The password compari-
son is performed following the write to the MSB, address 7B_h. This byte must be written last!
A four-byte burst-write sequence to address 78_h may be used as this will result in the MSB being written last. The new
password will not take effect until after a power-on reset occurs or a warm reset is performed using the RST bit in
OEMCFG0. This allows the new password to be verified before it takes effect. This field is reset to all zeros at power
on. Any values written to these locations will be readable by the host regardless of the locked/unlocked status of the
device. If OEMPWSET is set to zero (00000000_h), the MIC3000 will remain unlocked regardless of the contents of the
OEMPW field. This is the factory default security setting.
BYTE
3
2
1
0
Weight
OEM Password Entry, Most Significant Byte (Address = 7Bh)
OEM Password Entry, 2nd Most Significant Byte (Address = 7Ah)
OEM Password Entry, 2nd Least Significant Byte (Address = 79h)
OEM Password Entry, Least Significant Byte (Address = 78h)
USER Password Setting (USRPWSET)
D[7]
Read/write
D[6]
Read/write
D[5]
Read/write
D[4]
Read/write
D[3]
D[2]
Read/write Read/write
D[1]
D[0]
Read/write Read/write
Default Value
0000 0000_b = 00_h
Serial Address
A2_h = 1010001_b
Byte Address
250 = FA_h
This register is for setting the password required to access the USER area of the MIC3000’s memory and registers.
This field is compared to the USRPW field at serial address A2_h, byte 251. If the two fields match, access is allowed to
the USER areas of the MIC3000 non-volatile memory at serial addresses A0h and A2h. If a valid USER password has
not been entered, writes to the serial ID fields, USRCTRL, and the user scratchpad areas of A0_h and A2_h will not be
allowed, and USRPWSET will be unreadable (returns all zeroes).
A USER password is set by writing the new value into USRPWSET. The new password will not take effect until after a
power-on reset occurs or a warm reset is performed using the RST bit in OEMCFG0. This allows the new password to
be verified before it takes effect. This register is non-volatile and will be maintained through power and reset cycles. A
valid USER or OEM password is required for access to this register. Otherwise, this register will read as 00_h. Note: a
valid OEM password overrides the USER password setting. If a valid OEM password is currently in place, the user
password will have no effect.
October 2004
49
M9999-101204