T25S16AFEPR datasheet(65/74 Pages) HMSEMI

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7.5.19 Enter QPI Mode (38h)

The

HM25Q128A

upport both Standard/Dual/Quad Serial Peripheral Interface (SPI) and Quad

Peripheral Interface (QPI). However, SPI mode and QPI mode cannot be used at the same time. “Enter QPI

(38h)” instruction is the only way to switch the device from SPI mode to QPI mode.

Upon power-up, the default state of the device upon is Standard/Dual/Quad SPI mode. This provides full

backward compatibility with earlier generations of ZBIT serial flash memories. See Instruction Set Table

7.1-7.4 for all supported SPI commands. In order to switch the device to QPI mode, the Quad Enable (QE) bit

in Status Register-2 must be set to 1 first, and an “Enter QPI (38h)” instruction must be issued. If the Quad

Enable (QE) bit is 0, the “Enter QPI (38h)” instruction will be ignored and the device will remain in SPI mode.

See Instruction Set Table 7.5 for all the commands supported in QPI mode. When the device is switched from

SPI mode to QPI mode, the existing Write Enable and Program/Erase Suspend status, and the Wrap Length

setting will remain unchanged.

Figure 7.46 Enter QPI Instruction (SPI Mode only)

7.5.20 Exit QPI Mode (FFh)

In order to exit the QPI mode and return to the Standard/Dual/Quad SPI mode, an “Exit QPI (FFh)”

instruction must be issued. When the device is switched from QPI mode to SPI mode, the existing Write

Enable Latch (WEL) and Program/Erase Suspend status, and the Wrap Length setting will remain

unchanged.

Figure 7.47 Exit QPI Instruction (QPI Mode only)

HM25Q128A

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