S-25C010A Datasheet, PDF (15/37 Pages) Seiko Instruments Inc – CMOS SPI SERIAL E2PROM

Rev.1.0_00
CMOS SPI SERIAL E²PROM
S-25C010A/020A/040A
5. Write in the status register (WRSR)
The values of status register (BP1, BP0) can be rewritten by inputting the WRSR instruction. But b7, b6, b5, b4, b1, b0 of
status register cannot be rewritten. b7 to b4 are always “1” when reading the status register.
Before inputting the WRSR instruction, set bit WEL by the WREN instruction. The operation of WRSR is shown below.
Set the chip select ( CS ) “L” first. After that, input the instruction code and data from serial data input (SI). To start
WRSR Write (t_PR), set the chip select ( CS ) to “H” after inputting data or before inputting a rising of the next serial clock.
It is possible to confirm the operation status by reading the value of bit WIP during WRSR Write. Bit WIP is “1” during
Write, “0” during any other status. Bit WEL is reset when Write is completed.
With the WRSR instruction, the values of BP1 and BP0; which determine the area size the users can handle as the Read
Only memory; can be changed. But if the signal WP is in “L”, S-25C010A/020A/040A does not send the WRSR
instruction (Refer to “„ Protect Operation”).
Bit BP1, BP0 keep the value which is the one prior to the WRSR instruction during the WRSR instruction. The newly
updated value is changed when the WRSR instruction has completed.
To cancel the WRSR instruction, input the clock different from a specified value (n = 16clock) while CS is in “L”.
CS
WP
High / Low
SCK
SI
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Instruction
Inputs Data in the Status Register
X
b7 b6 b5 b4 b3 b2 b1 b0
SO
Remark X = Don’t care.
High-Z
Figure 14 WRSR operation
Seiko Instruments Inc.
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