M35B32 datasheet(22/44 Pages) STMICROELECTRONICS

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Instructions

M35B32

22/44

DocID18391 Rev 4

6.6

Read Data Bytes (READ)

The device is first selected by driving Chip Select (S) low. The instruction code for the Read

Data Bytes (READ) instruction is followed by a 2-byte address (A15-A0), each bit being

latched-in during the rising edge of Serial Clock (C). Then the memory contents, at that

address, is shifted out on Serial Data Output (Q), each bit being shifted out, at a maximum

frequency fR, during the falling edge of Serial Clock (C).

The instruction sequence is shown in Figure 12

The first byte addressed can be at any location. The address is automatically incremented

to the next higher address after each byte of data is shifted out. The whole memory can,

therefore, be read with a single Read Data Bytes (READ) instruction. When the highest

address (0FFFh) is reached, the address counter rolls over to 0000h, allowing the read

sequence to be continued indefinitely.

The Read Data Bytes (READ) instruction is terminated by driving Chip Select (S) high. Chip

Select (S) can be driven high at any time during data output. Any Read Data Bytes (READ)

instruction, while an Erase, Program or Write cycle is in progress, is rejected without having

any effects on the cycle that is in progress.

Figure 12. Read Data Bytes (READ) instruction sequence and data-out sequence

1. Address bits A15 to A12 are Don’t Care.

AI01793D

3456789 10

20 21 22 23 24 25 26 27

14 13

3210

28 29 30

76543

High Impedance

Data Out 1

Instruction

16-Bit Address

MSB

Data Out 2

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