Document Number: 002-00833 Rev. *L
Page 15 of 74
S29VS256R
S29VS128R
S29XS256R
S29XS128R
Legend:
L = Logic 0, H = Logic 1, X = can be either V
IL
or V
IH
.
= rising edge.
Note:
1. Data is delivered by a read operation only after the burst initial wait state count has been satisfied.
6.5
Device ID and CFI (ID-CFI)
There are two traditional methods for systems to identify the type of Flash memory installed in the system. One has been
traditionally been called Autoselect and is now referred to as Device Identification (ID). A command is used to enable an address
space overlay where up to 16 word locations can be read to get JEDEC manufacturer identification (ID), device ID, and some
configuration and protection status information from the Flash memory. The system can use the manufacturer and device IDs to
select the appropriate driver software to use with the Flash device. The other method is called Common Flash Interface (CFI). It also
uses a command to enable an address space overlay where an extendable table of standard information about how the Flash
memory is organized and behaves can be read. With this method the driver software does not have to be written with the specifics of
each possible memory device in mind. Instead the driver software is written in a more general way to handle many different devices
but adjusts the driver behavior based on the information in the CFI table stored in the Flash memory. Traditionally these two address
spaces have used separate commands and were separate overlays. However, the mapping of these two address spaces are
non-overlapping and so can be combined in to a single address space and appear together in a single overlay. Either of the
traditional commands used to access (enter) the Autoselect (ID) or CFI overlay will cause the now combined ID-CFI address map to
appear.
A write at any sector address, in bank zero, having the least significant byte address value of AAh, with xx98h or xx90h data,
switches the addressed sector to an overlay of the ID-CFI address map. These are called ID-CFI Enter commands and are only valid
when written to the specified bank when it is in read mode. The ID-CFI address map appears within, and replaces Flash Array data
of, the selected sector address range. The ID-CFI enter commands use the same address and data values used on previous
generation memories to access the JEDEC Manufacturer ID (Autoselect) and Common Flash Interface (CFI) information,
respectively. While the ID-CFI address space is overlaid, any write with xxF0h data to the device will remove the overlay and return
the selected sector to showing Flash memory array data. Thus, the ID-CFI address space and commands are backward compatible
with standard memory discovery algorithms.
Within the ID-CFI address map there are two subsections:
For the complete address map, see Tables in
Section 11.2, Device ID and Common Flash Memory Interface Address Map
Synchronous Mode Operations
Latch Starting Burst Address by CLK
- ADM mode
L
H
H
L
Addr In
Addr In
H
Latch Upper Starting Burst Address by CLK
(S29XS256R and S29XS128R Only)
L
L
H
L
X
Addr In
H
Latch Lower Starting Burst Address by CLK
(S29XS256R and S29XS128R Only)
L
H
H
L
X
Addr In
H
Burst Read and advance to next address
L
L
H
H
X
Data Output Valid
H
Terminate current Burst cycle
X
X
X
X
X
High-Z
H
Table 7. Device Bus Operations (Continued)
Operation
CE#
OE#
WE#
CLK
AVD#
A28-A16
A/DQ 15-A/DQ0
RESET#
Table 8. ID-CFI Address Map Overview
Byte Address
Description
Size Allocated (Bytes)
Read/Write
(SA) + 00000h to 0001Fh
JEDEC ID (traditional Autoselect values)
32
Read Only
(SA) + 00020h to CEh h
CFI data structure
174
Read Only
