X25F064/032/016/008
PRINCIPLES OF OPERATION
formatted as follows:
The X25F064/032/016/008 family are SerialFlash
Memory designed to interface directly with the synchro-
nous serial peripheral interface (SPI) of many popular
microcontroller families.
7
6
5
4
3
2
1
0
PPEN
X
X
X
BL1
BL0
PEL PIP
6685 PGM T02.2
PPEN, BL0, and BL1 are set by the PRSR instruction.
PEL and PIP are “read-only” and automatically set by
other operations.
The X25F064/032/016/008 family contains an 8-bit
instruction register. It is accessed via the SI input, with
data being clocked in on the rising SCK. CS must be
LOWandtheHOLD andPP inputsmustbeHIGHduring
the entire operation. The PP input is “Don’t Care” if
PPEN is set “0”.
The Programming-In-Process (PIP) bit indicates
whether the X25F064/032/016/008 device is busy
with a program operation. When set to a “1”
programming is in progress, when set to a “0” no
programming is in progress. During programming, all
other bits are set to “1”.
Table 1 contains a list of the instructions and their
operation codes. All instructions, addresses and data
are transferred MSB first.
The Program Enable Latch (PEL) bit indicates the
status of the program enable latch. When set to a “1” the
latch is set; when set to a “0” the latch is reset.
DatainputissampledonthefirstrisingedgeofSCKafter
CS goes LOW. SCK is static, allowing the user to stop
the clock and then resume operations. If the clock line is
shared with other peripheral devices on the SPI bus, the
user can assert the HOLD input to place the X25F064/
032/016/008 into a “PAUSE” condition. After
releasing HOLD, the X25F064/032/016/008 device will
resume operation from the point when HOLD was first
asserted.
The Block Lock (BL0 and BL1) bits are nonvolatile and
allow the user to select one of four levels of protection.
The X25F064/032/016/008 device array is divided into
four equal segments. One, two, or all four of the seg-
ments may be locked. That is, the user may read the
segments, but will be unable to alter (program) data
within the selected segments. The partitioning is con-
trolled as illustrated below.
Program Enable Latch
The X25F064/032/016/008 device contains a
program enable latch. This latch must be SET before a
program operation will be completed internally. The
PREN instruction will set the latch and the PRDI
instruction will reset the latch. This latch is automatically
reset on power-up and after the completion of a sector
program or status register write cycle.
Status Register Bits
Array Addresses
Locked
BL1
BL0
0
0
1
1
0
1
0
1
None
upper fourth
upper half
All
6685 PGM T03.1
Status Register
Program-Protect Enable
The RDSR instruction provides access to the status
register. The status register may be read at any time,
even during a program cycle. The status register is
The Program-Protect-Enable bit (PPEN) in the
X25F064/032/016/008 status register acts as an
enable bit for the PP pin.
Table 1. Instruction Set
Instruction Name
PREN
Instruction Format*
0000 0110
Operation
Set the Program Enable Latch (Enable Program Operations)
Reset the Program Enable Latch (Disable Program Operations)
Read Status Register
PRDI
0000 0100
RDSR
0000 0101
PRSR
0000 0001
Program Status Register
READ
0000 0011
Read from Memory Array beginning at Selected Address
Program Memory Array beginning at Selected Address
(32 Bytes)
PROGRAM
0000 0010
6685 PGM T04.2
*Instructions are shown MSB in leftmost position. Instructions are transferred MSB first.
3
XICOR [ XICOR INC. ]
