DSM2150F5V STMicroelectronics, DSM2150F5V Datasheet - Page 21

• Manufacturer Part Number: DSM2150F5V
• Description: DSM (Digital Signal Processor System Memory) for Analog Devices DSPs (3.3V Supply)
• Manufacturer: STMicroelectronics

Toggle Flag (DQ6)
The device offers an alternative way for determin-
ing when the Flash memory Program cycle is com-
pleted. During the internal WRITE operation and
when the Sector Select FS0-FS7 (or CSBOOT0-
CSBOOT3) is true, the Toggle Flag Bit (DQ6) tog-
gles from ’0’ to ’1’ and ’1’ to ’0’ on subsequent at-
tempts to read any byte of the memory. When the
DSM2150F5V is configured to operate in 16-bit
mode, status READs must occur at even address-
es, DQ8 - DQ15 are insignificant and can be ig-
nored.
When the internal cycle is complete, the toggling
stops and the data READ on the Data Bus is the
addressed memory byte/word. The device is now
accessible for a new READ or WRITE operation.
The cycle is finished when two successive READs
yield the same output data.
–
–
–
The Toggle Flag Bit (DQ6) is effective after the
fourth WRITE operation (for a Program
instruction sequence) or after the sixth WRITE
operation (for an Erase instruction sequence).
If the byte/word to be programmed belongs to
a protected Flash memory sector, the
instruction sequence is ignored.
If all the Flash memory sectors selected for
erasure are protected, the Toggle Flag Bit
(DQ6) toggles to ’0’ for t
returns to the previous addressed byte.
TIMOUT
and then
Error Flag (DQ5)
During a normal Program or Erase cycle, the Error
Flag Bit (DQ5) is to ’0.’ This bit is set to ’1’ when
there is a failure during Flash memory byte/word
Program operation, Sector Erase, or Bulk Erase
operation.
In the case of Flash memory programming, the Er-
ror Flag Bit (DQ5) indicates the attempt to program
a Flash memory bit from the programmed state,
logic ’0,’ to the erased state, logic ’1’, which is not
valid. The Error Flag Bit (DQ5) may also indicate a
Time-out condition while attempting to program a
byte/word.
In case of an error in a Flash memory Sector Erase
or byte/word Program cycle, the Flash memory
sector in which the error occurred or to which the
programmed byte/word belongs must no longer be
used. Other Flash memory sectors may still be
used. The Error Flag Bit (DQ5) is reset after a Re-
set Flash instruction sequence.
Erase Time-out Flag (DQ3)
The Erase Time-out Flag Bit (DQ3) reflects the
time-out period allowed between two consecutive
Sector Erase instruction sequence bytes/words.
The Erase Time-out Flag Bit (DQ3) is reset to ’0’
after a Sector Erase cycle for a time period t
unless an additional Sector Erase instruction se-
quence is decoded. After this time period, or when
the additional Sector Erase instruction sequence
is decoded, the Erase Time-out Flag Bit (DQ3) is
set to ’1.’
DSM2150F5V
TIMOUT
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