DocID023214 Rev 6

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M95M01-A125 M95M01-A145

Instructions

39

4.5

Read from Memory Array (READ)

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.

Figure 9. Read from Memory Array (READ) sequence

1. Depending on the memory size, as shown in Table 7, the most significant address bits are Don’t Care.

C

D

AI13878

S

Q

23

2

1

3456789 10

28 29 30 31 32 33 34 35

22 21

3210

36 37 38

76543

1

7

0

High Impedance

Data Out 1

Instruction

24-bit address

0

MSB

MSB

2

39

Data Out 2