m29f800at STMicroelectronics, m29f800at Datasheet - Page 10

• Manufacturer Part Number: m29f800at
• Description: 8 Mbit 1mb X8 Or 512kb X16, Boot Block Single Supply Flash Memory
• Manufacturer: STMicroelectronics

M29F800AT, M29F800AB
Figure 3. Data Polling Flowchart
Toggle Bit (DQ6). The Toggle Bit can be used to
identify whether the Program/Erase Controller has
successfully completed its operation or if it has re-
sponded to an Erase Suspend. The Toggle Bit is
output on DQ6 when the Status Register is read.
During Program and Erase operations the Toggle
Bit changes from ’0’ to ’1’ to ’0’, etc., with succes-
sive Bus Read operations at any address. After
successful completion of the operation the memo-
ry returns to Read mode.
During Erase Suspend mode the Toggle Bit will
output when addressing a cell within a block being
erased. The Toggle Bit will stop toggling when the
Program/Erase Controller has suspended the
Erase operation.
Figure 4, Data Toggle Flowchart, gives an exam-
ple of how to use the Data Toggle Bit.
Error Bit (DQ5). The Error Bit can be used to
identify errors detected by the Program/Erase
Controller. The Error Bit is set to ’1’ when a Pro-
10/21
at VALID ADDRESS
NO
READ DQ5 & DQ7
READ DQ7
START
DATA
DATA
DQ7
DQ5
DQ7
FAIL
= 1
=
=
YES
NO
NO
YES
YES
PASS
AI01369
Figure 4. Data Toggle Flowchart
gram, Block Erase or Chip Erase operation fails to
write the correct data to the memory. If the Error
Bit is set a Read/Reset command must be issued
before other commands are issued. The Error bit
is output on DQ5 when the Status Register is read.
Note that the Program command cannot change a
bit set at ’0’ back to ’1’ and attempting to do so will
cause an error. One of the Erase Commands must
be used to set all the bits in a block or in the whole
memory from ’0’ to ’1’.
Erase Timer Bit (DQ3). The Erase Timer Bit can
be used to identify the start of Program/Erase
Controller operation during a Block Erase com-
mand. Once the Program/Erase Controller starts
erasing the Erase Timer Bit is set to ’1’. Before the
Program/Erase Controller starts the Erase Timer
Bit is set to ’0’ and additional blocks to be erased
may be written to the Command Interface. The
Erase Timer Bit is output on DQ3 when the Status
Register is read.
NO
DQ5 & DQ6
READ DQ6
TOGGLE
TOGGLE
START
READ
DQ6
DQ5
DQ6
FAIL
= 1
=
=
YES
YES
YES
NO
NO
PASS
AI01370