M95640-DRE Datasheet, PDF (18/41 Pages) STMicroelectronics – 64-Kbit serial SPI bus EEPROM - 105C operation

Instructions
M95640-DRE
4.4
Write Status Register (WRSR)
The Write Status Register (WRSR) instruction allows new values to be written to the Status
Register. Before it can be accepted, a Write Enable (WREN) instruction must previously
have been executed.
The Write Status Register (WRSR) instruction is entered (MSB first) by driving Chip Select
(S) low, sending the instruction code followed by the data byte on Serial Data input (D), and
driving the Chip Select (S) signal high.
The contents of the SRWD and BP1, BP0 bits are updated after the completion of the
WRSR instruction, including the Write cycle (t_W).
The Write Status Register (WRSR) instruction has no effect on the b6, b5, b4, b1 and b0 bits
in the Status Register (see Table 2: Status Register format).
The Status Register functionality is detailed in Section 3.4.2: Status Register and data
protection.
The instruction is not accepted, and is not executed, if a Write cycle is currently in progress.
Figure 8. Write Status Register (WRSR) sequence
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