Common Flash Interface (CFI)
M29FxxxFT, M29FxxxFB
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. Addresses used to retrieve the data are shown in the
following tables:
Table 31.: Query Structure Overview,
Table 32.: CFI Query Identification String,
Table 33.: CFI Query System Interface Information,
Table 34.: Device Geometry Definition,
Table 35.: Primary Algorithm-Specific Extended Query Table
Table 36.: Security Code Area
The CFI data structure also contains a security area where a 64-bit unique security number
is written (see Table 36.: 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. Issue a Read command to return to Read mode.
Table 31. Query Structure Overview
Address
x16 x8
Sub-section Name
Description
10h
1Bh
27h
20h
36h
4Eh
CFI Query Identification String
System Interface Information
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 Primary Algorithm
40h
61h
80h
C2h
Query table
(optional)
Security Code Area
64 bit unique device number
Query data are always presented on the lowest order data outputs.
Table 32. CFI Query Identification String
Address
x16 x8
Data
Description
Value
"Q"
10h
11h
12h
13h
14h
15h
16h
20h
22h
24h
26h
28h
2Ah
2Ch
0051h
0052h
0059h
0002h
0000h
0040h
0000h
Query Unique ASCII String "QRY"
"R"
"Y"
AMD
Primary Algorithm Command Set and Control Interface ID code 16 bit
ID code defining a specific algorithm
Compatible
Address for Primary Algorithm extended Query table (see Table 34.) P = 40h
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NUMONYX [ NUMONYX B.V ]
