EN25QH32
Quad Input / Output FAST_READ (EBh)
The Quad Input/Output FAST_READ (EBh) instruction is similar to the Dual I/O Fast Read (BBh)
instruction except that address and data bits are input and output through four pins, DQ0, DQ1, DQ2 and
DQ3 and six dummy clocks are required prior to the data output. The Quad I/O dramatically reduces
instruction overhead allowing faster random access for code execution (XIP) directly from the Quad SPI.
The Quad Input/Output FAST_READ (EBh) instruction enable quad throughput of Serial Flash in read
mode. In SPI mode, the QE bit needs to be assigned through WRSR to set to “1” before sending the
SPI instruction Quad Input/Output FAST_READ (EBh). If the system goes into Full Quad I/O (EQPI),
this QE bit becomes no affection since WP# and HOLD# function will be disabled by EQPI mode and
Quad Input/Output FAST_READ (EBh) will be always available in EQPI mode.
The address is latching on rising edge of CLK, and data of every four bits (interleave on 4 I/O pins) shift
out on the falling edge of CLK at a maximum frequency FR. The first address can be any location. The
address is automatically increased to the next higher address after each byte data is shifted out, so the
whole memory can be read out at a single Quad Input/Output FAST_READ instruction. The address
counter rolls over to 0 when the highest address has been reached. Once writing Quad Input/Output
FAST_READ instruction, the following address/dummy/data out will perform as 4-bit instead of previous
1-bit.
The sequence of issuing Quad Input/Output FAST_READ (EBh) instruction is: CS# goes low ->
sending Quad Input/Output FAST_READ (EBh) instruction -> 24-bit address interleave on DQ3, DQ2,
DQ1 and DQ0 -> 6 dummy cycles -> data out interleave on DQ3, DQ2, DQ1 and DQ0 -> to end Quad
Input/Output FAST_READ (EBh) operation can use CS# to high at any time during data out, as shown
in Figure 15.
The instruction sequence is shown in Figure 15.1 while using the Enable Quad Peripheral Interface mode (EQPI)
(38h) command.
Figure 15. Quad Input / Output Fast Read Instruction Sequence Diagram
This Data Sheet may be revised by subsequent versions
or modifications due to changes in technical specifications.
©2004 Eon Silicon Solution, Inc., www.eonssi.com
28
Rev. E, Issue Date: 2012/01/30
EON [ EON SILICON SOLUTION INC. ]
