M95040 datasheet(21/42 Pages) STMICROELECTRONICS

21 / 42 page

M95040, M95020, M95010

Instructions

21/42

6.5

Read from Memory Array (READ)

As shown in Figure 11, 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). For the M95040, the most significant address bit, A8, is incorporated as bit b3 of

the instruction byte, as shown in Table 4. The address is loaded into an internal address

If Chip Select (S) continues to be driven Low, an internal bit-pointer is automatically

incremented at each clock cycle, and the corresponding data bit is shifted out.

When the highest address is reached, the address counter rolls over to zero, allowing the

Read cycle to be continued indefinitely. The whole memory can, therefore, be read with a

single READ instruction.

The Read cycle is terminated by driving Chip Select (S) High. The rising edge of the Chip

Select (S) signal can occur at any time during the cycle.

The first byte addressed can be any byte within any page.

The instruction is not accepted, and is not executed, if a Write cycle is currently in progress.

Figure 11.

Read from Memory Array (READ) sequence

Depending on the memory size, as shown in Table 6, the most significant address bits are Don’t Care.

Table 6.

Address range bits

Device

M95040

M95020

M95010

Address Bits

A8-A0

A7-A0

A6-A0

AI01440E

3456789 10 11 12 13 14 15 16 17 18 19

A6 A5 A4 A3 A2 A1 A0

20 21 22

76543

High Impedance

Data Out

Instruction

Byte Address

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