M24256E-FDW6TP datasheet(21/46 Pages) STMICROELECTRONICS

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6.5

Read identification page

Following a start condition the bus master sends a device select code with the RW bit (RW) set to '0'. The device

acknowledges this and waits for the address bytes where the identification page is located. The device responds

to each address byte with an acknowledge bit. The bits A6/A0 define the byte address inside the identification

page. Then, the bus master sends another start condition, and repeats the same device select code but with

the RW bit set to '1'. The device acknowledges this, and outputs the contents of the identification page. See in

Section 5.5 Device addressing (Table 5, Table 6 and Table 7) how to address identification page.

The number of bytes to read in the ID page must not exceed the page boundary (e.g.: when reading the

identification page from location 10d, the number of bytes should be less than or equal to 54, as the ID page

boundary is 64 bytes). After the 64th byte of the identification page, there is no “roll-over” to the beginning of the

page. To terminate the stream of data byte, the bus master must not acknowledge the byte, and must generate a

stop condition, as shown in Figure 15.

Figure 12. Random read identification page

Dev sel *

Byte addr

Data out N

Random

Address

Read

Dev sel *

Data out

Dev sel *

Byte addr

Sequential

Random

Read

Dev sel *

Data out1

ACK

NO ACK

ACK

NO ACK

*: The seven most significant bits of the device select code of a random read must be identical.

M24256E-F

Read identification page

DS12687 - Rev 3

page 21/46

M24256E-FDW6TP Datasheet(PDF) 21 Page - STMicroelectronics