Common Flash Interface (CFI)
M29W640GH, M29W640GL, M29W640GT, M29W640GB
Appendix B
Common Flash Interface (CFI)
The Common Flash Interface is a JEDEC approved, standardized data structure that can be
read from the Flash memory device. It allows a system software to query the device to
determine various electrical and timing parameters, density information and functions
supported by the memory. The system can interface easily with the device, enabling the
software to upgrade itself when necessary.
When the CFI Query Command is issued the device enters CFI Query mode and the data
structure is read from the memory. Tables
and
show the addresses
used to retrieve the data. The CFI data structure also contains a security area where a 64 bit
unique security number is written (see
This area can be
accessed only in Read mode by the final user. It is impossible to change the security
number after it has been written by Numonyx.
Table 30.
Address
Sub-section Name
x16
10h
1Bh
27h
40h
61h
x8
20h
36h
4Eh
80h
C2h
CFI Query Identification String
System Interface Information
Device Geometry Definition
Primary Algorithm-specific Extended
Query table
Security Code Area
Command set ID and algorithm data offset
Device timing & voltage information
Flash device layout
Additional information specific to the
Primary Algorithm (optional)
64 bit unique device number
Description
Query structure overview
(1)
1. Query data are always presented on the lowest order data outputs.
Table 31.
Address
CFI query identification string
(1)
Data
Description
Value
“Q”
"R"
"Y"
AMD
Compatible
P = 40h
x16
10h
11h
12h
13h
14h
15h
16h
17h
18h
19h
1Ah
x8
20h
22h
24h
26h
28h
2Ah
2Ch
2Eh
30h
32h
34h
0051h
0052h Query Unique ASCII String "QRY"
0059h
0002h Primary Algorithm Command Set and Control Interface ID code
0000h 16 bit ID code defining a specific algorithm
0040h Address for Primary Algorithm extended Query table (see
0000h
0000h Alternate Vendor Command Set and Control Interface ID Code
0000h second vendor - specified algorithm supported
0000h
Address for Alternate Algorithm extended Query table
0000h
NA
NA
1. Query data are always presented on the lowest order data outputs (DQ7-DQ0) only. DQ8-DQ15 are ‘0’.
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