M950X0-W datasheet(27/46 Pages) STMICROELECTRONICS

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M950x0-W M950x0-R M950x0-DF

Instructions

6.9

Read Lock Status (available only in M95040-D device)

The Read Lock Status (RDLS) 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 5). 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 16.

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

currently in progress.

Figure 16. Read Lock Status sequence

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