Multibyte Write. For the Multibyte Write mode, the

mode can be started from any address in the

memory. The master sends from one up to 4 bytes

of data, which are each acknowledged by the mem-

ory. The transfer is terminated by the master gen-

erating a STOP condition. The duration of the write

are accessed on 2 rows (that is have different

values for the 5 most significant address bits A6-

A2), the programming time is then doubled to a

maximum of 20ms. Writing more than 4 bytes in the

Multibyte Write mode may modify data bytes in an

adjacent row (one row is 8 bytes long). However,

the Multibyte Write can properly write up to 8

consecutive bytes only if the first address of these

8 bytes is the first address of the row, the 7 following

bytes being written in the 7 following bytes of this

same row.

Page Write. For the Page Write mode, the MODE

to 8 bytes to be written in a single write cycle,

provided that they are all located in the same ’row’

in the memory: that is the 5 most significant mem-

ory address bits (A7-A3) are the same. The master

sends from one up to 8 bytes of data, which are

each acknowledged by the memory. After each

byte is transfered, the internal byte address counter

(3 least significant bits only) is incremented. The

transfer is terminated by the master generating a

STOP condition. Care must be taken to avoid ad-

dress counter ’roll-over’ which could result in data

being overwritten. Note that, for any write mode,

the generation by the master of the STOP condition

starts the internal memory program cycle. All inputs

are disabled until the completion of this cycle and

the memory will not respond to any request.

WRITE Cycle

in Progress

AI01099B

Next

Operation is

Addressing the

Memory

START Condition

DEVICE SELECT

with RW = 0

ACK

Returned

YES

NO

YES

NO

ReSTART

STOP

Proceed

WRITE Operation

Proceed

Random Address

READ Operation

Send

Byte Address

First byte of instruction

with RW = 0 already

decoded by ST24xxx

Figure 7. Write Cycle Polling using ACK

9/16

ST24/25C01, ST24C01R, ST24/25W01