M95020-DWDW4TP datasheet(22/41 Pages) STMICROELECTRONICS

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Instructions

M95020-A125 M95020-A145

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DocID025284 Rev 5

4.8

Write Identification Page (WRID)

The Write Identification Page instruction is used to write the Identification Page (additional

page of 16 byte which can also be permanently locked in Read-only mode).

The Chip Select signal (S) is first driven low, and then the bits of the instruction byte,

address bytes, and at least one data byte are shifted in (MSB first) on Serial Data input (D).

Address bit A7 must be 0 and the other address bits are Don't Care except the lower

address bits [A3:A0] (it might be easier to define these bits as 0, as shown in Table 6).

The self-timed Write cycle starts from the rising edge of Chip Select (S), and continues for a

period tW (as specified in Table 14).

Figure 13. Write Identification Page sequence

The instruction is discarded, and is not executed, under the following conditions:

•

If a Write cycle is already in progress

•

If the Block Protect bits (BP1,BP0) = (1,1)

•

If one of the conditions defined in Section 3.4.1: Protocol control is not satisfied.

4.9

Read Lock Status (RDLS)

The Read Lock Status instruction is used to read the lock status.

To send this instruction to the device, Chip Select (S) first has to be driven low. The bits of

the instruction byte and address bytes are then shifted in (MSB first) on Serial Data input

(D). Address bit A7 must be 1; all other address bits are Don't Care (it might be easier to

define these bits as 0, as shown in Table 6). The Lock bit is the LSB (Least Significant Bit) of

the byte read on Serial Data output (Q). It is at ‘1’ when the lock is active and at ‘0’ when the

lock is not active. If Chip Select (S) continues to be driven low, the same data byte is shifted

out.

The read cycle is terminated by driving Chip Select (S) high. The instruction sequence is

shown in Figure 14.

The Read Lock Status instruction is not accepted and not executed if a Write cycle is

currently in progress.

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