AM28F020A Datasheet, PDF (14/35 Pages) Advanced Micro Devices – 2 Megabit (256 K x 8-Bit) CMOS 12.0 Volt, Bulk Erase Flash Memory with Embedded Algorithms

Write Operation Status
Data Polling—DQ7
The device features Data# Polling as a method to indi-
cate to the host system that the Embedded algorithms
are either in progress or completed.
While the Embedded Programming algorithm is in oper-
ation, an attempt to read the device at a valid address
will produce the complement of expected Valid data on
DQ7. Upon completion of the Embedded Program algo-
rithm an attempt to read the device at a valid address will
produce Valid data on DQ7. The Data# Polling feature is
valid after the rising edge of the second WE# pulse of
the two write pulse sequence.
While the Embedded Erase algorithm is in operation,
DQ7 will read “0" until the erase operation is com-
pleted. Upon completion of the erase operation, the
data on DQ7 will read “1.” The Data# Polling feature is
valid after the rising edge of the second WE# pulse of
the two Write pulse sequence.
The Data# Polling feature is only active during Embed-
ded Programming or erase algorithms.
See Figures 3 and 4 for the Data# Polling timing spec-
ifications and diagrams. Data# Polling is the standard
method to check the write operation status, however,
an alternative method is available using Toggle Bit.
START
Read Byte
(DQ0–DQ7)
Addr = VA
VA = Byte address for programming
= XXXXh during chip erase
Yes
DQ7 = Data
?
No
No
DQ5 = 1
?
Yes
Read Byte
(DQ0–DQ7)
Addr = VA
DQ7 = Data ^Yes
?
No
Fail
Pass
Note:
DQ7 is rechecked even if DQ5 = “1” because DQ7 may change simultaneously with DQ5 or after DQ5.
Figure 3. Data# Polling Algorithm
17502D-8
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Am28F020A