M95040 datasheet(13/42 Pages) STMICROELECTRONICS

13 / 42 page

M95040, M95020, M95010

Operating features

13/42

Operating features

4.1

Hold Condition

The Hold (HOLD) signal is used to pause any serial communications with the device without

resetting the clocking sequence.

During the Hold condition, the Serial Data Output (Q) is high impedance, and Serial Data

Input (D) and Serial Clock (C) are Don’t Care.

To enter the Hold condition, the device must be selected, with Chip Select (S) Low.

Normally, the device is kept selected, for the whole duration of the Hold condition.

Deselecting the device while it is in the Hold condition, has the effect of resetting the state of

the device, and this mechanism can be used if it is required to reset any processes that had

been in progress.

The Hold condition starts when the Hold (HOLD) signal is driven Low at the same time as

Serial Clock (C) already being Low (as shown in Figure 5).

The Hold condition ends when the Hold (HOLD) signal is driven High at the same time as

Serial Clock (C) already being Low.

Figure 5 also shows what happens if the rising and falling edges are not timed to coincide

with Serial Clock (C) being Low.

Figure 5.

Hold Condition activation

4.2

Status Register

Figure 6 shows the position of the Status Register in the control logic of the device. This

description of the Status Register bits, see Section 6.3: Read Status Register (RDSR).

AI02029D

HOLD

Hold

Condition

Hold

Condition

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