IS66/67WVR4M8ALL/BLL

Integrated Silicon Solution, Inc.- www.issi.com

20

Rev. A2

07/08/2024

5.9 IN-BAND RESET OPERATION

The device offers an additional feature of In-Band RESET function, which uses existing SPI signals to initiate a

hardware reset, which is different from existing software reset/hardware reset (dedicated RESET# pin);

-

Existing software reset commands often depend on the device being in a particular mode before they are effective. This

makes software based reset sequences depend on slave device and mode.

-

Dedicated RESET# pin requires additional pin over traditional 8-pins of SPI device. Also it requires 1 more signal for reset

operation.

In Band-RESET operation requires 2-signal pins; CE# and SIO0.

•

CE# is driven active low to select the SPI slave

(note1)

•

Clock (CLK) remains stable in either a high or low state

….(note 2)

•

SIO0 is driven low by the b

us master, simultaneously with CE# going active low……(note 3)

•

CE# is driven inactive

… (note 4)

•

Repeat the above 4 steps, each time alternating the state of SIO0.

•

After the fourth CE# pulse, the slave triggers its intern

al reset……..(note 5)

Note 1

This powers up the SPI slave

Note 2

This prevents any confusion with a command, as no command bits are transferred (clocked)

Note 3

No SPI bus slave drives SIO0 during CE# low before a transition of clock. Slave streaming output active is not

allowed until after the first edge of clock.

Note 4

The slave captures the state of SIO0 on the rising edge of CE#

Note 5

SIO0 is low on the first CE#, high on the second, low on the third,

high on the fourth … (This provides a 5th, unlike random noise)

NOTE:

This reset sequence is not intended to be used at normal power on, but to be used only when the device is not

responding to the system. This reset sequence will be operational from any state that the device may be in. During the

reset process, the device will ignore any chip select (command). In Band-Reset function is supported by optional device

(option R) only.