Common Flash interface
M58LT256JST, M58LT256JSB
Appendix B
Common Flash interface
The CFI (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 device enters CFI query mode and the
data structure is read from the memory. Tables 35, 36, 37, 38, 39, 40, 41, 42, 43 and 44
show the addresses used to retrieve the data. The query data is always presented on the
lowest order data outputs (DQ0-DQ7), the other outputs (DQ8-DQ15) are set to 0.
The CFI data structure also contains a security area where a 64-bit unique security number
is written (see Figure 4: Protection Register memory map). This area can only be accessed
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 Array command to return to read mode.
Table 35. Query structure overview
Offset
Sub-section name
Description
000h Reserved
Reserved for algorithm-specific information
Command set ID and algorithm data offset
Device timing and voltage information
Flash device layout
010h CFI query identification string
01Bh System interface information
027h Device geometry definition
Primary algorithm-specific extended
query table
Additional information specific to the primary
algorithm (optional)
P
Alternate algorithm-specific extended
query table
Additional information specific to the alternate
algorithm (optional)
A
Lock Protection Register
Unique device number and
User programmable OTP
080h Security code area
1. The Flash memory display the CFI data structure when CFI Query command is issued. In this table are
listed the main sub-sections detailed in Tables 36, 37, 38 and 39. Query data is always presented on the
lowest order data outputs.
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NUMONYX [ NUMONYX B.V ]
