M95320-R datasheet(23/48 Pages) STMICROELECTRONICS

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M95320-W M95320-R M95320-DR

Instructions

Doc ID 5711 Rev 14

23/48

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

6.6

Write to Memory Array (WRITE)

As shown in Figure 12, to send this instruction to the device, Chip Select (S) is first driven

low. The bits of the instruction byte, address byte, and at least one data byte are then shifted

in, on Serial Data Input (D).

The instruction is terminated by driving Chip Select (S) high at a byte boundary of the input

data. The self-timed Write cycle, triggered by the Chip Select (S) rising edge, continues for a

period tW (as specified in AC characteristics in Section 9: DC and AC parameters), at the

end of which the Write in Progress (WIP) bit is reset to 0.

Figure 12.

Byte Write (WRITE) sequence

Depending on the memory size, as shown in Table 5, the most significant address bits are Don’t Care.

In the case of Figure 12, Chip Select (S) is driven high after the eighth bit of the data byte

has been latched in, indicating that the instruction is being used to write a single byte.

However, if Chip Select (S) continues to be driven low, as shown in Figure 13, the next byte

of input data is shifted in, so that more than a single byte, starting from the given address

towards the end of the same page, can be written in a single internal Write cycle.

Each time a new data byte is shifted in, the least significant bits of the internal address

counter are incremented. If the number of data bytes sent to the device exceeds the page

boundary, the internal address counter rolls over to the beginning of the page, and the

previous data there are overwritten with the incoming data. (The page size of these devices

is 32 bytes).

AI01795D

3456789 10

20 21 22 23 24 25 26 27

14 13

3210

28 29 30

High Impedance

Instruction

16-Bit Address

765432

Data Byte

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