M35B32 datasheet(25/44 Pages) STMICROELECTRONICS

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M35B32

Instructions

6.8

Page Program (PP)

The Page Program instruction has be used when addressing erased bytes (see Note:

below).

The Page Program (PP) instruction allows bytes to be programmed in the memory

(changing bits from 1 to 0, only). Before it can be accepted, a Write Enable (WREN)

instruction must have been previously executed. (This sets the Write Enable Latch (WEL)

bit).

The Page Program (PP) instruction is entered by driving Chip Select (S) low, followed by the

instruction code, two address bytes and at least one data byte on Serial Data Input (D). The

transmitted data must NOT exceed the addressed page boundary as a wrap round would

corrupt the data from the start address of the same page. Chip Select (S) must be driven low

for the entire duration of the sequence.

The instruction sequence is shown in Figure 14.

Chip Select (S) must be driven high after the eighth bit of the last data byte has been latched

in, otherwise the Page Program (PP) instruction is not executed.

As soon as Chip Select (S) is driven high, the self-timed Page Program cycle is initiated.

The Page Program cycle lasts tPP when the Data sector is addressed, or tFP when the Event

sector is addressed. While the Page Program cycle is in progress, the Status Register may

be read to check the value of the Write In Progress (WIP) bit. The Write In Progress (WIP)

bit is at 1 during the self-timed Page Program cycle, and it is at 0 when the cycle is

completed. The Write Enable Latch (WEL) bit is also reset (or not) once the self-timed Page

Program cycle is complete, depending on the logical level applied on the W input pin and

the value of the decoded address, as shown in Table 4.

A Page Program (PP) instruction applied to a page that is Hardware Protected is not

executed.

Any Page Program (PP) instruction, while an Erase, Program or Write cycle is in progress,

is rejected without having any effects on the cycle that is in progress.

Note:

The Program instruction does not include an Erase cycle (unlike the Page Write instruction,

which includes two cycles: Erase+ Program). As a consequence, the Page Program

instruction has to be used only when pointing to locations which were previously erased.

In addition, as the M35B32 offers the ECC feature (see Section 6.9), it is important to check,

before programming data with the Page Program instruction, that the addressed bytes are

inside an erased area defined as a multiple of four bytes.

Example: to program data inside locations [003h-011h], the minimum erased area has to be

[000h-013h], because location 003h belongs to the four bytes [000h-003h] and location

011h belongs to the four bytes [010h-013h].

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