ACE25QC200GLFMLTH datasheet(27/64 Pages) ACE

27 / 64 page

ACE25QC200GL

2M BIT SPI NOR FLASH

VER 1.1

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 two pins SI, SO, /WP and /HOLD and four Dummy

clocks are required in SPI mode 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 Fast Read Quad I/O Instruction.

Fast Read Quad I/O with “Continuous Read Mode”

The Fast Read Quad I/O instruction can operate at the highest possible frequency of fC (see AC Electrical

Characteristics). 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 14.

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 EBh instruction code, as shown in Figure 15. 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.

It is recommended to input FFh on SI for the next instruction (8 clocks), to ensure M4 = 1 and return the

device to normal operation.

Figure13. Fast Read Sequence Diagram (Previous command set (M5-4) =(1,0))

ACE25QC200GLFMLTH Datasheet(PDF) 27 Page - ACE Technology Co., LTD.