Intel Advanced+ Boot Block Flash Memory (C3)
Datasheet
Intel Advanced+ Boot Block Flash Memory (C3)
May 2005
Order Number: 290645, Revision: 023
43
The contents of the Status Register are latched on the falling edge of OE# or CE# (whichever
occurs last) which prevents possible bus errors that might occur if Status Register contents change
while being read. CE# or OE# must be toggled with each subsequent status read, or the Status
Register will not indicate completion of a Program or Erase operation.
When the WSM is active, SR[7] will indicate the status of the WSM; the remaining bits in the
Status Register indicate whether the WSM was successful in performing the preferred operation
10.1.4.1
Clear Status Register
The WSM can set Status Register bits 1 through 7 and can clear bits 2, 6, and 7, but the WSM
cannot clear Status Register bits 1, 3, 4 or 5. Because bits 1, 3, 4, and 5 indicate various error
conditions, these bits can be cleared only through the Clear Status Register (0x50) command. By
allowing the system software to control the resetting of these bits, several operations may be
performed (such as cumulatively programming several addresses or erasing multiple blocks in
sequence) before reading the Status Register to determine if an error occurred during that series.
Clear the Status Register before beginning another command or sequence. The Read Array
command must be issued before data can be read from the memory array. Resetting the device also
clears the Status Register.
10.2
Program Mode
Programming is executed using a two-write cycle sequence. The Program Setup command (0x40)
is issued to the CUI, followed by a second write that specifies the address and data to be
programmed. The WSM will execute a sequence of internally timed events to program preferred
bits of the addressed location, then verify the bits are sufficiently programmed. Programming the
memory results in specific bits within an address location being changed to a “0.” If users attempt
to program “1”s, the memory cell contents do not change and no error occurs.
The Status Register indicates programming status. While the program sequence executes, status bit
7 is “0.” The Status Register can be polled by toggling either CE# or OE#. While programming, the
only valid commands are Read Status Register, Program Suspend, and Program Resume.
When programming is complete, the program-status bits must be checked. If the programming
operation was unsuccessful, SR[4] is set to indicate a program failure. If SR[3] is set, then VPP was
not within acceptable limits, and the WSM did not execute the program command. If SR[1] is set, a
program operation was attempted on a locked block and the operation was aborted.
The Status Register should be cleared before attempting the next operation. Any CUI instruction
can follow after programming is completed; however, to prevent inadvertent Status Register reads,
be sure to reset the CUI to read-array mode.
10.2.1
12-Volt Production Programming
When VPP is between 1.65 V and 3.6 V, all program and erase current is drawn through the VCC
pin.
Note:
If VPP is driven by a logic signal, VIH min = 1.65 V. That is, VPP must remain above 1.65 V to
perform in-system flash modifications.