SA25F020 Datasheet, PDF (19/37 Pages) List of Unclassifed Manufacturers – 2Mb Serial Flash with 25MHz SPI Bus Interface

The RDSR command requires the following
sequence:
1. The CSb pin is pulled low to select
the device and the RDSR opcode is
transmitted on the SI pin.
SA25F020 Advanced Information
SAIFUN
19
2. The data on the SI pin becomes
Don't Care.
3. The data from the status register is
shifted out on the SO pins, with the
D7 bit first and the D0 bit last, as
shown in Figure 10.
CS
SCK
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Instruction
SI
Status Register Out
Status Register Out
SO
High Impedance
765 4 321 0 7 654 32 1 07
MSB
MSB
MSB
Figure 10. Read Status Register (RDSR) Instruction Sequence