W25Q32BV_13 Datasheet, PDF (35/78 Pages) Winbond – 3V 32M-BIT SERIAL FLASH MEMORY WITH DUAL AND QUAD SPI

W25Q32BV
7.2.16 Word Read Quad I/O (E7h)
The Word Read Quad I/O (E7h) instruction is similar to the Fast Read Quad I/O (EBh) instruction except
that the lowest Address bit (A0) must equal 0 and only two 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 Enable bit (QE) of Status Register-2 must be set to
enable the Word Read Quad I/O Instruction.
Word Read Quad I/O with “Continuous Read Mode”
The Word Read Quad I/O instruction can further reduce instruction overhead through setting the
“Continuous Read Mode” bits (M7-0) after the input Address bits (A23-0), as shown in Figure 15a. The
upper nibble of the (M7-4) controls the length of the next Fast Read Quad I/O instruction through the
inclusion or exclusion of the first byte instruction code. The lower nibble bits of the (M3-0) are don’t care
(“x”). However, the IO pins should be high-impedance prior to the falling edge of the first data out clock.
If the “Continuous Read Mode” bits M5-4 = (1,0), then the next Fast Read Quad I/O instruction (after /CS
is raised and then lowered) does not require the E7h instruction code, as shown in Figure 15b. This
reduces the instruction sequence by eight clocks and allows the Read address to be immediately entered
after /CS is asserted low. If the “Continuous Read Mode” bits M5-4 do not equal to (1,0), the next
instruction (after /CS is raised and then lowered) requires the first byte instruction code, thus returning to
normal operation. A “Continuous Read Mode” Reset instruction can also be used to reset (M7-0) before
issuing normal instructions (See 7.2.20 for detail descriptions).
/CS
CLK
Mode 3
Mode 0
IO₀
IO₁
IO₂
IO₃
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
Instruction (E7h)
A23-16 A15-8
A7-0
M7-0 Dummy
IOs switch from
Input to Output
20 16 12 8 4 0 4 0
40404
21 17 13 9 5 1 5 1
51515
22 18 14 10 6 2 6 2
62626
23 19 15 11 7 3 7 3
73
Byte 1
73
Byte 2
7
Byte 3
Figure 15a. Word Read Quad I/O Instruction Sequence (Initial instruction or previous M5-4  10)
- 35 -
Publication Release Date: October 04,2013
Revision I