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 30, 31, 32, 33, 34, and 35, 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 Table 35: Security code area). 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.
(1)
Table 30. Query structure overview
Address
Sub-section Name
Description
x16
x8
10h
1Bh
27h
20h CFI Query Identification String
36h System Interface Information
4Eh Device Geometry Definition
Command set ID and algorithm data offset
Device timing & voltage information
Flash device layout
Primary Algorithm-specific Extended Additional information specific to the
40h
61h
80h
Query table
Primary Algorithm (optional)
C2h Security Code Area
64 bit unique device number
1. Query data are always presented on the lowest order data outputs.
(1)
Table 31. CFI query identification string
Address
Data
Description
Value
x16
x8
10h
11h
12h
13h
14h
20h 0051h
“Q”
"R"
"Y"
22h 0052h Query Unique ASCII String "QRY"
24h 0059h
26h 0002h
AMD
Primary Algorithm Command Set and Control Interface ID code
16 bit ID code defining a specific algorithm
Compatible
28h 0000h
15h 2Ah 0040h
16h 2Ch 0000h
17h 2Eh 0000h
Address for Primary Algorithm extended Query table (see
Table 34)
P = 40h
NA
Alternate Vendor Command Set and Control Interface ID Code
second vendor - specified algorithm supported
18h
19h
30h 0000h
32h 0000h
Address for Alternate Algorithm extended Query table
NA
1Ah 34h 0000h
1. Query data are always presented on the lowest order data outputs (DQ7-DQ0) only. DQ8-DQ15 are ‘0’.
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