SE97 Datasheet, PDF (17/54 Pages) NXP Semiconductors – DDR memory module temp sensor with integrated SPD, 3.3 V

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.
slave address (memory)
SDA S 1 0 1 0 A2 A1 A0 0 A
word address
data to memory
A
DATA n
A
START condition
R/W acknowledge
from slave
acknowledge
from slave
acknowledge
from slave
data to memory
DATA n + 15
AP
Fig 15. Page Write timing
acknowledge
from slave
STOP condition;
write to the memory is performed
002aab247
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:
SE97_5
Product data sheet
• 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)
Rev. 05 — 6 August 2009
© NXP B.V. 2009. All rights reserved.
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