M24256E-FDW6TP datasheet(20/46 Pages) STMICROELECTRONICS

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6.4.1

Random address read

A dummy write is first performed to load the address into this address counter (as shown in Figure 11) but without

sending a stop condition. Then, the bus master sends another start condition, and repeats the device select code,

with the RW bit set to 1. The device acknowledges this, and outputs the contents of the addressed byte. To

terminate the transfer master, master must not acknowledge the byte, and sends a stop condition.

6.4.2

Current address read

For the current address read operation, following a start condition, the bus master only sends a device select

code with the RW bit set to 1. The device acknowledges this, and outputs the byte addressed by the internal

address counter. The counter is then incremented. The bus master terminates the transfer with a stop condition,

as shown in Figure 11, without acknowledging the byte.

Note:

The address counter value is defined by instructions accessing either the memory or the register or the

identification page. When accessing the register or the identification page, the address counter value is loaded

with the register or the identification page byte location, therefore the next current address read in the memory

uses this new address counter value. When accessing the memory, it is safer to use the random address read

instruction (this instruction loads the address counter with the byte location to read in the memory) instead of the

current address read instruction.

6.4.3

Sequential read

This operation can be used after a current address read or a random address read. The bus master does

acknowledge the data byte output, and sends additional clock pulses so that the device continues to output the

next byte in sequence. To terminate the stream of bytes, the bus master must not acknowledge the last byte, and

must generate a stop condition, as shown in Figure 11.

The output data comes from consecutive addresses, with the internal address counter automatically incremented

after each byte output. After the last memory address, the address counter “rolls-over”, and the device continues

to output data from memory address 00h.

M24256E-F

Read operations on memory array

DS12687 - Rev 3

page 20/46

M24256E-FDW6TP Datenblatt(PDF) 20 Page - STMicroelectronics