MX29L3211 Macronix International, MX29L3211 Datasheet - Page 11

• Manufacturer Part Number: MX29L3211
• Description: CMOS SINGLE VOLTAGE PAGEMODE FLASH EEPROM
• Manufacturer: Macronix International

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P/N:PM0641
READ STATUS REGISTER
The MXIC's 32 Mbit flash family contains a status
register which may be read to determine when a program
or erase operation is complete, and whether that
operation completed successfully. The status register
may be read at any time by writing the Read Status
command to the CIR. After writing this command, all
subsequent read operations output data from the status
register until another valid command sequence is
written to the CIR. A Read Array command must be
written to the CIR to return to the Read Array mode.
The status register bits are output on Q3 - Q7(table 6)
whether the device is in the byte-wide (x8) or word-wide
(x16) mode for the MX29L3211. In the word-wide mode
the upper byte, Q(8:15) is set to 00H during a Read
Status command. In the byte-wide mode, Q(8:14) are
tri-stated and Q15/A-1 retains the low order address
function. Q0-Q1 is set to 0H in either x8 or x16 mode.
It should be noted that the contents of the status register
are latched on the falling edge of OE or CE whichever
occurs last in the read cycle. This prevents possible bus
errors which might occur if the contents of the status
register change while reading the status register. CE or
OE must be toggled with each subsequent status read,
or the completion of a program or erase operation will not
be evident.
The Status Register is the interface between the
microprocessor and the Write State Machine (WSM).
When the WSM is active, this register will indicate the
status of the WSM, and will also hold the bits indicating
whether or not the WSM was successful in performing
the desired operation. The WSM sets status bits four
through seven and clears bits six and seven, but cannot
clear status bits four and five. If Erase fail or Program fail
status bit is detected, the Status Register is not cleared
until the Clear Status Register command is written. The
MX29L3211 automatically outputs Status Register data
when read after Chip Erase, Sector Erase, Page Program
or Read Status Command write cycle. The default state
of the Status Register after powerup and return from
deep power-down mode is (Q7, Q6, Q5, Q4) = 1000B.
Q3 = 0 or 1 depends on sector-protect status, can not be
changed by Clear Status Register Command or Write
State Machine.
11
CLEAR STATUS REGISTER
The Erase fail status bit (Q5) and Program fail status bit
(Q4) are set by the write state machine, and can only be
reset by the system software. These bits can indicate
various failure conditions(see Table 6). By allowing the
system software to control the resetting of these bits,
several operations may be performed (such as
cumulatively programming several pages or erasing
multiple blocks in squence). The status register may
then be read to determine if an error occurred during that
programming or erasure series. This adds flexibility to
the way the device may be programmed or erased.
Additionally, once the program(erase) fail bit happens,
the program (erase) operation can not be performed
further. The program(erase) fail bit must be reset by
system software before further page program or sector
(chip) erase are attempted. To clear the status register,
the Clear Status Register command is written to the CIR.
Then, any other command may be issued to the CIR.
Note again that before a read cycle can be initiated, a
Read command must be written to the CIR to specify
whether the read data is to come from the Array, Status
Register or Silicon ID.
MX29L3211
REV. 0.3, NOV. 06, 2001