SE97TP datasheet(17/54 Pages) NXP

17 / 54 page

SE97_5

Product data sheet

Rev. 05 — 6 August 2009

17 of 54

NXP Semiconductors

SE97

DDR memory module temp sensor with integrated SPD, 3.3 V

7.10.1.2

Page Write

The SE97 contains 256 bytes of data, arranged in 16 pages of 16 bytes each. The page is

selected by the four Most Signiﬁcant Bits (MSB) of the address byte presented to the

device after the slave address, while the four Least Signiﬁcant Bits (LSB) point to the byte

within the page. By loading more than one data byte into the device, up to an entire page

can be written in one write cycle (see Figure 15). The internal byte address counter will

increment automatically after each data byte. If the master transmits more than

16 data bytes, then earlier bytes will be overwritten by later bytes in a wrap-around fashion

within the selected page. The internal write cycle is started following the STOP condition

created by the master.

7.10.1.3

Acknowledge polling

Acknowledge polling can be used to determine if the SE97 is busy writing or is ready to

accept commands. Polling is implemented by sending a ‘Selective Read’ command

(described in Section 7.10.3 “Read operations”) to the device. The SE97 will not

acknowledge the slave address as long as internal write is in progress.

7.10.2 Memory protection

The lower half (the ﬁrst 128 bytes) of the memory can be write protected by special

EEPROM commands without an external control pin. The SE97 features three types of

memory write protection instructions, and three respective read Protection instructions.

The level of write-protection (set or clear) that has been deﬁned using these instructions

remained deﬁned even after power cycle.

The memory protection commands are:

• Permanent Write Protection (PWP)

• Reversible Write Protection (RWP)

• Clear Write Protection (CWP)

• Read Permanent Write Protection (RPWP)

• Read Reversible Write Protection (RRWP)

• Read Clear Write Protection (RCWP)

Fig 15. Page Write timing

A2 A1 A0

slave address (memory)

START condition

R/W acknowledge

from slave

acknowledge

from slave

word address

SDA

data to memory

DATA n

acknowledge

from slave

002aab247

STOP condition;

write to the memory is performed

data to memory

DATA n

+ 15

acknowledge

from slave

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