Specifications

163
3706C–MICRO–2/11
AT89LP3240/6440
25.4 Status Register
The current state of the memory may be accessed by reading the status register. The status reg-
ister is shown in Table 25-3.
25.5 DATA Polling
The AT89LP3240/6440 implements DATA polling to indicate the end of a programming cycle.
While the device is busy, any attempted read of the last byte written will return the data byte with
the MSB complemented. Once the programming cycle has completed, the true value will be
accessible. During Erase the data is assumed to be FFH and DATA
polling will return 7FH.
When writing multiple bytes in a page, the DATA
value will be the last data byte loaded before
programming begins, not the written byte with the highest physical address within the page.
25.6 Flash Security
The AT89LP3240/6440 provides two Lock Bits for Flash Code and Data Memory security. Lock
bits can be left unprogrammed (FFh) or programmed (00h) to obtain the protection levels listed
in Table 25-4. Lock bits can only be erased (set to FFh) by Chip Erase. Lock bit mode 2 disables
programming of all memory spaces, including the User Signature Array and User Configuration
Fuse
s. User fuses must be programmed before enabling Lock bit mode 2 or 3. Lock bit mode 3
implements mode 2 and also blocks reads from the code and data memories; however, reads of
the User Signature Array, Atmel Signature Array, and User Configuration Fuses are still allowed.
The Lock Bits will not disable FDATA or IAP programming initiated by the applic
ation software.
Table 25-3.
Status Register
–
–––
LOAD SUCCESS WRTINH BUSY
Bit76543210
Symbol Function
LOAD
Load flag. Cleared low by the load page buffer command and set high by the next memory write. This flag signals that
the page buffer was previously loaded with data by the load page buffer command.
SUCCESS
Success flag. Cleared low at the start of a programming cycle and will only be set high if the programming cycle
completes without interruption from the brownout detector.
WRTINH
Write Inhibit flag. Cleared low by the brownout detector (BOD) whenever programming is inhibited due to V
DD
falling
below the minimum required programming voltage. If a BOD episode occurs during programming, the SUCCESS flag
will remain low after the cycle is complete.
BUSY
Busy flag. Cleared low whenever the memory is busy programming or if write is currently inhibited.
Table 25-4. Lock Bit Protection Modes
Program Lock Bits (by address)
Mode 00h 01h Protection Mode
1 FFh FFh No program lock features
200hFFhFurther programming of the Flash is disabled
3 00h 00h
Further programming of the Flash is disabled and verify (read) is also
disabled; OCD is disabled