M95020-DWDW4TP datasheet(18/41 Pages) STMICROELECTRONICS

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Instructions

M95020-A125 M95020-A145

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DocID025284 Rev 5

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 byte are then shifted in, on Serial Data Input

(D).The address is loaded into an internal address register, and the byte of data at that

address is shifted out, on Serial Data Output (Q).

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

M95020-DWDW4TP Datasheet(PDF) 18 Page - STMicroelectronics