Common Flash interface (CFI)
M29W128GH, M29W128GL
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 Read CFI Query command is issued, the memory enters Read CFI Query mode and read
operations output the CFI data. Table 35, Table 36, Table 37, Table 38, Table 39 and Table 40 show the
addresses (A-1, A0-A7) 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 40: 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 35. Query structure overview
Address
Sub-section name
Description
x 16
x 8
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
Additional information specific to the primary
algorithm (optional)
40h
61h
80h Primary algorithm-specific extended query table
C2h Security code area
64 bit unique device number
1. Query data are always presented on the lowest order data outputs.
(1)
Table 36. CFI query identification string
Address
Data
Description
Value
x 16
x 8
10h
11h
12h
13h
14h
15h
16h
17h
18h
19h
1Ah
20h
22h
24h
26h
28h
2Ah
2Ch
2Eh
30h
32h
34h
0051h
‘Q’
‘R’
‘Y’
0052h Query Unique ASCII String ‘QRY’
0059h
0002h
Primary algorithm command set and control interface ID code 16 bit
ID code defining a specific algorithm
AMD
compatible
0000h
0040h
0000h
0000h
0000h
0000h
0000h
Address for primary algorithm extended query table (see Table 39)
P = 40h
NA
Alternate vendor command set and control interface ID code second
vendor - specified algorithm supported
Address for alternate algorithm extended query table
NA
1. Query data are always presented on the lowest order data outputs (DQ7-DQ0) only. DQ8-DQ15 are ‘0’.
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