M95M01-A125 M95M01-A145
4.5 Read from Memory Array (READ)
Instructions
The READ instruction is used to read the content of the memory.
As shown in
Figure 9 , to send this instruction to the device, Chip Select (S) is first driven
low.
The bits of the instruction byte and address bytes are shifted in (MSB first) on Serial Data
Input (D) and the addressed data byte is then shifted out (MSB first) on Serial Data Output
(Q). The first addressed byte can be any byte within any page.
If Chip Select (S) continues to be driven low, the internal address register is automatically incremented, and the next byte of data is shifted out. The whole memory can therefore be read with a single READ instruction.
When the highest address is reached, the address counter rolls over to zero, allowing the
Read cycle to be continued indefinitely.
The Read cycle is terminated by driving Chip Select (S) high at any time when the data bits are shifted out on Serial Data Output (Q).
The instruction is not accepted, and is not executed, if a Write cycle is currently in progress.
S
C
Figure 9. Read from Memory Array (READ) sequence
0 1 2 3 4 5 6 7 8 9 10
Instruction
28 29 30 31 32 33 34 35 36 37 38 39
24-bit address
D
23 22 21
MSB
3 2 1 0
Q
High Impedance
Data Out 1
7 6 5 4 3 2
MSB
1 0 7
Data Out 2
AI13878
1. Depending on the memory size, as shown in Table 7 , the most significant address bits are Don’t Care.
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