SA25F020 Datasheet, PDF (23/37 Pages) List of Unclassifed Manufacturers – 2Mb Serial Flash with 25MHz SPI Bus Interface

Read Data Bytes (READ)
Reading the memory via the serial SPI link
requires the following sequence:
1. After the CSb line is pulled low to
select the device, the READ
opcode is transmitted via the SI
line, followed by the 3-byte address
to be read (address bits A23 to A18
are Don’t Care).
2. Upon completion, any data on the
SI line is ignored.
3. The data (D7-D0) at the specified
address is then shifted out onto the
SO line. Each bit is shifted out at a
maximum SCK frequency of F_SCK.
SA25F020 Advanced Information
SAIFUN
23
If only one byte is to be read, the CSb line
should be driven high after the data comes
out. The READ sequence can be
continued, as the byte address is
automatically incremented and data
continues to shift out. When the highest
address is reached, the address counter
rolls over to the lowest address, enabling
the entire memory to be read in one
continuous READ cycle. The instruction
sequence is shown in Figure 14.
Driving CSb high terminates the READ
instruction, which can be done at any time
during data output. Any READ instruction
executed while an Erase, Program or
WRSR cycle is in progress is rejected
without having any effect on the cycle in
progress.
CS
SCK
0 1 2 3 4 5 6 7 8 9 10 28 29 30 31 32 33 34 35 36 37 38 39
Instruction
24-Bit
Address
SI
23 22 21
3210
SO
High Impedance
76
MSB
DATA OUT 1
54321
DATA OUT 2
07
MSB
Figure 14. Read (READ) Instruction Sequence