m24256-bw STMicroelectronics, m24256-bw Datasheet - Page 20

• Manufacturer Part Number: m24256-bw
• Description: 512 Kbit And 256 Kbit Serial I?c Bus Eeprom With Three Chip Enable Lines
• Manufacturer: STMicroelectronics

Device operation
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Read operations
Read operations are performed independently of the state of the Write Control (WC) signal.
After the successful completion of a Read operation, the device’s internal address counter is
incremented by one, to point to the next byte address.
Random Address Read (in memory array)
A dummy Write is first performed to load the address into this address counter (as shown in
Figure
condition, and repeats the device select code, with the Read/Write bit (RW) set to 1. The
device acknowledges this, and outputs the contents of the addressed byte. The bus master
must not acknowledge the byte, and terminates the transfer with a Stop condition.
Current Address Read (in memory array)
For the Current Address Read operation, following a Start condition, the bus master only
sends a device select code with the Read/Write bit (RW) 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
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
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.
Read Identification Page
The Identification page can be read by issuing an ID Read instruction. This instruction uses
the same protocol and format as the Random Address Read in memory array, except for the
Device Type Identifier which has to be 1011b.
If the Identification page is locked, the data bytes are read as FFh.
11.) but without sending a Stop condition. Then, the bus master sends another Start
11., without acknowledging the byte.
Figure 11.
Doc ID 6757 Rev 15
M24512-Dx, M24512-x, M24256-Bx