w25q16bv Winbond Electronics Corp America, w25q16bv Datasheet - Page 29

• Manufacturer Part Number: w25q16bv
• Description: 16m-bit Serial Flash Memory With Dual And Quad Spi
• Manufacturer: Winbond Electronics Corp America

10.2.14 Fast Read Quad I/O (EBh)
The Fast Read Quad I/O (EBh) instruction is similar to the Fast Read Dual I/O (BBh) instruction except
that address and data bits are input and output through four pins IO
clocks are required prior to the data output
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 Fast read Quad I/O Instruction.
Fast Read Quad I/O with “Continuous Read Mode”
The Fast 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 13a. 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 (M7-0) equals “Ax” hex, then the next Fast Read Quad I/O instruction
(after /CS is raised and then lowered) does not require the EBh instruction code, as shown in figure 13b.
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 (M7-0) are any value other than
“Ax” hex, 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 be used to reset
(M7-0) before issuing normal instructions (See 10.2.33 for detailed descriptions).
Figure 13a. Fast Read Quad I/O Instruction Sequence Diagram (M7-0 = 0xh or NOT Axh)
.
The Quad I/O dramatically reduces instruction overhead
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Publication Release Date: March 13, 2009
0
, IO
1
, IO
2
Byte 1
Byte 1
and IO
Preliminary - Revision B
W25Q16BV
Byte 2
Byte 2
3
and four Dummy