M95040-DRMF3TP datasheet(22/41 Pages) STMICROELECTRONICS

22 / 41 page

Instructions

M95040-A125 M95040-A145

22/41

DocID024225 Rev 6

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 A8 must be 0 and the other upper address bits are Don't Care (it might be easier

to define these bits as 0, as shown in Table 6). The lower address bits [A4:A0] define the

byte address inside the identification page.

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

Note:

The first three bytes of the Identification page offer the Device Identification code (Please

refer to Section 3.5: Identification page for more information). Using the WRID command on

these first three bytes overwrites the Device Identification code.

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.

M95040-DRMF3TP датащи(PDF) 22 Page - STMicroelectronics