Serial Quad I/O (SQI) Flash Memory
SST26VF016 / SST26VF032
Data Sheet
Index Jump
Index Jump allows the host to read data using relative addressing instead of absolute addressing; in
some cases this reduces the number of input clocks required to access data. The SST26VF016/032
support three Index Jump options:
•
•
•
Read Page-Index-jump to address index within 256 Byte page
Read Index-jump to address index within 64 KByte block
Read Block-Index - jump to address index in another 64 KByte block.
Index Jumps following a Burst Read command are referenced from the last input address. For exam-
ple, the device initiates a 64-Byte Read Burst instruction from address location 1EH and outputs an
arbitrary number of Bytes. When the device issues a Read Page-Index instruction with 40H as the off-
set, the device will output data from address location 5EH. Index Jump operations following a High
Speed Read (continuous read) instruction are referenced from the last address from which the full byte
of data was output.
Data output by any of the Index-Jump commands follows the pattern of the last non-Index-Jump com-
mand. For example, a Read Page-Index command following a Read Burst, with 64-Byte wrap length,
will continue to deliver data that wraps at 64-Byte boundaries after jumping to the address specified in
the Read Page-Index command.
Read Page-Index (Read PI)
The Read Page-Index (Read PI) instruction increments the address counter within a page of 256
Bytes. To execute a Read PI operation the host drives CE# low then sends the Read PI command
cycle (08H), one address cycle, and one dummy cycle. Each cycle is two nibbles (clocks) long, most
significant nibble first.
The address cycle contain a two’s complement number that specifies the number of bytes and direc-
tion the address pointer will jump. For example, to jump ahead 127 Bytes A1:A0 = 7FH; to jump back
127 Bytes A1:A0 = 81H.
The Read PI command does not cross 256 Byte page boundaries. If the jump distance exceeds the
256 Byte boundary, the address pointer wraps around to the beginning of the page, if the jump is for-
ward, or to the end of the page, if the jump is backward. After the dummy cycle, the device outputs data
on the falling edge of the SCK signal starting from the specified address location.
Read Index
The Read Index (Read I) instruction increments the address counter a specified number of bytes within
a 64 KByte block. To execute a Read I operation the host drives CE# low then sends the Read I com-
mand cycle (09H), two address cycles, and two dummy cycles. Each cycle is two nibbles (clocks) long,
most significant nibble first.
The address cycles contain a two’s complement number that specifies the number of bytes and direc-
tion the address pointer will jump. For example, to jump ahead 256 Bytes, the address cycles would be
0100H; to jump back 256 Bytes, the address cycles would be FF00H.
The Read I command can not cross 64 KByte block boundaries, but it can cross boundaries of smaller
blocks. If the jump distance exceeds the 64 KByte block boundary, the address pointer wraps around
to the beginning of the block, if the jump is forward, and to the end of the block, if the jump is backward.
After the dummy cycles, the device outputs data on the falling edge of the SCK signal starting from the
specified address location.
©2010 Silicon Storage Technology, Inc.
S71359-05-000
06/10
17
SST [ SILICON STORAGE TECHNOLOGY, INC ]
