Instructions

M95040, M95020, M95010

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6

Instructions

Each instruction starts with a single-byte code, as summarized in Table 4.

If an invalid instruction is sent (one not contained in Table 4), the device automatically

deselects itself.

6.1

Write Enable (WREN)

The Write Enable Latch (WEL) bit must be set prior to each WRITE and WRSR instruction.

The only way to do this is to send a Write Enable instruction to the device.

As shown in Figure 7, to send this instruction to the device, Chip Select (S) is driven Low,

and the bits of the instruction byte are shifted in, on Serial Data Input (D). The device then

enters a wait state. It waits for a the device to be deselected, by Chip Select (S) being driven

High.

Figure 7.

Write Enable (WREN) sequence

Table 4.

Instruction set

Instruction

Description

Instruction Format

WREN

Write Enable

1.

X = Don’t Care.

WRDI

Write Disable

0000 X100(1)

RDSR

Read Status Register

0000 X101(1)

WRSR

Write Status Register

0000 X001(1)

READ

Read from Memory Array

(2)

2.

A8 = 1 for the upper half of the memory array of the M95040, and 0 for the lower half, and is Don’t Care for

other devices.

WRITE

Write to Memory Array

(2)

C

D

AI01441D

S

Q

2

1

34567

High Impedance

0

Instruction