ASAHI KASEI
[AK2572]
9.2 Write Protect Operation
Accessible range and Device address via Digital I/F are determined by Write Protect setting as shown in Table
9-1.
Table 9-1 Write Protect Operation
Item
WP = “H”
1010 xxx
WP = “L”
x
1010 000
R_WP_CTRL
Device address
ACK
0
1
1010 000
When corresponding Device address is input via Digital I/F [*1]
Access to
EEPROM / Register
A0h only
A0h only
Read only
Full Access [*2]
Read only
Self-Operation Self-Operation
Operation mode
Transition to any operation mode is possible
Mode only
Mode only
Sequential write operation of EEPROM is possible in
every 16 bytes. Sequential write operation of Register
(Address after A8h/3Eh is folded back to A8h/00h).
Sequential read operation of both EEPROM and
Register is possible within the designated address
－
－
Page Write
area respectively. Address after A6h/FFh is folded Sequential read is possible in
back to A0h/00h in EEPROM and address after accessible EEPROM area.
A8h/3Fh is folded back to A8h/00h in Register.
Sequential Read
“Non-actual space“ address is not skipped.
［*1］ ACK signal is not returned during the writing operation into EEPROM.
［*2］ When Write Protect is released (WP-pin＝“H” and R_WP_CTRL＝”0”), writing into R_PWR_SEL[1:0] at
address =A8h / 2Fh is possible in Self-Operation Mode.
About Write Protect Setting
* The data for fully accessible setting (E_WP_CTRL＝”0”, E_PASSWD＝”0”) is programmed atAKM.
(a) Write Protect operation is “ON” when WP-pin at “L”.
WP-pin setting has a higher priority than R_WP_CTRL (Register for Write Protect setting).
(b) Write Protect operation is controlled to be “ON ” or “OFF” by R_WP_CTRL when WP-pin is at “H”.
Access to R_WP_CTRL is possible only when R_PASSWD [7:0] (Register for Write Protect password), which
is loaded via digital I/F, agrees with E_PASSWD [7:0] that is the password retained in advance.
Be noted that other than “00h” should be written into E_PASSWD [7:0] to enable Write Protect.
- R_WP_CTRL＝”0” → Full access is possible
- R_WP_CTRL＝”1” → Only the area in Device address＝’1010 000（A0h）‘ is accessible (Read Only),
especially only Write Protect control register (R_PASSWD, R_WP_CTRL) are writable
Accordingly, when Self-Operation Mode is set by R_WP_CTRL＝“1”, access to the adjusting data is executed
as the following procedure,
(1) Make it enable to access to R_WP_CTRL by setting the same value to R_PASSWD as is retained in
E_PASSWD in advance.
(2) Set R_WP_CTRL＝ “0” to enable full access.
(3) When to modify EEPROM content, shift the mode into EEPROMAccess Mode and then modify data.
At the Power-on or when Self-Operation Mode is set, R_PASSWD is reset to “00h” and E_WP_CTRL value
is loaded to R_WP_CTRL. So, if E_WP_CTRL is set to “0”, Write Protect operation is automatically released
at Power-on or when Self-Operation Mode is set.
Table 9-2 Write Protect Control Register / EEPROM
Register
A0h / 7Eh
A0h / 7Fh
EEPROM
A6h / 7Eh
A6h / 7Fh
D7
－
D6
－
D5
－
D4
－
D3
－
D2
－
D1
－
D0
WP_CTRL
PASSWD
-35-
< MS0290-E-01>
2004/8
AKM [ ASAHI KASEI MICROSYSTEMS ]
