W25M02GV
use the DI input pin to serially write instructions, addresses or data to the device on the rising edge of
CLK. The DO output pin is used to read data or status from the device on the falling edge of CLK.
SPI bus operation Mode 0 (0,0) and 3 (1,1) are supported. The primary difference between Mode 0 and
Mode 3 concerns the normal state of the CLK signal when the SPI bus master is in standby and data is
not being transferred to the Serial Flash. For Mode 0, the CLK signal is normally low on the falling and
rising edges of /CS. For Mode 3, the CLK signal is normally high on the falling and rising edges of /CS.
6.1.3 Dual SPI Instructions
The W25M02GV supports Dual SPI operation when using instructions such as “Fast Read Dual Output
(3Bh)” and “Fast Read Dual I/O (BBh)”. These instructions allow data to be transferred to or from the
device at two to three times the rate of ordinary Serial Flash devices. The Dual SPI Read instructions are
ideal for quickly downloading code to RAM upon power-up (code-shadowing) or for executing non-speed-
critical code directly from the SPI bus (XIP). When using Dual SPI instructions, the DI and DO pins
become bidirectional I/O pins: IO0 and IO1.
6.1.4 Quad SPI Instructions
The W25M02GV supports Quad SPI operation when using instructions such as “Fast Read Quad Output
(6Bh)”, “Fast Read Quad I/O (EBh)” and “Quad Program Data Load (32h/34h)”. These instructions allow
data to be transferred to or from the device four to six times the rate of ordinary Serial Flash. The Quad
Read instructions offer a significant improvement in continuous and random access transfer rates allowing
fast code-shadowing to RAM or execution directly from the SPI bus (XIP). When using Quad SPI
instructions the DI and DO pins become bidirectional IO0 and IO1, and the /WP and /HOLD pins become
IO2 and IO3 respectively.
6.1.5 Hold Function
For Standard SPI and Dual SPI operations, the /HOLD signal allows the W25M02GV operation to be
paused while it is actively selected (when /CS is low). The /HOLD function may be useful in cases where
the SPI data and clock signals are shared with other devices. For example, consider if the page buffer
was only partially written when a priority interrupt requires use of the SPI bus. In this case the /HOLD
function can save the state of the instruction and the data in the buffer so programming can resume where
it left off once the bus is available again. The /HOLD function is only available for standard SPI and Dual
SPI operation, not during Quad SPI. When a Quad SPI command is issued, /HOLD pin will act as a
dedicated IO pin (IO3).
To initiate a /HOLD condition, the device must be selected with /CS low. A /HOLD condition will activate on
the falling edge of the /HOLD signal if the CLK signal is already low. If the CLK is not already low the
/HOLD condition will activate after the next falling edge of CLK. The /HOLD condition will terminate on the
rising edge of the /HOLD signal if the CLK signal is already low. If the CLK is not already low the /HOLD
condition will terminate after the next falling edge of CLK. During a /HOLD condition, the Serial Data
Output (DO) is high impedance, and Serial Data Input (DI) and Serial Clock (CLK) are ignored. The Chip
Select (/CS) signal should be kept active (low) for the full duration of the /HOLD operation to avoid
resetting the internal logic state of the device.
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