X24645
Page Write
Flow 1. ACK Polling Sequence
The X24645 is capable of a 32-byte page write opera-
tion. It is initiated in the same manner as the byte write
operation, but instead of terminating the write cycle af-
ter the first data word is transferred, the master can
transmit up to thirty-one more bytes. After the receipt of
each byte, the X24645 will respond with an acknowl-
edge.
WRITE OPERATION
COMPLETED
ENTER ACK POLLING
ISSUE
START
After the receipt of each byte, the five low order ad-
dress bits are internally incremented by one. The high
order eight bits of the address remain constant. If the
master should transmit more than 32 bytes prior to gen-
erating the stop condition, the address counter will “roll
over” and the previously written data will be overwrit-
ten. As with the byte write operation, all inputs are dis-
abled until completion of the internal write cycle. Refer
to Figure 6 for the address, acknowledge, and data
transfer sequence.
ISSUE SLAVE
ADDRESS AND R/W = 0
ISSUE STOP
ACK
NO
RETURNED?
YES
Acknowledge Polling
NEXT
NO
The Max Write Cycle Time can be significantly reduced
using Acknowledge Polling. To initiate Acknowledge
Polling, the master issues a start condition followed by
the Slave Address Byte for a write or read operation. If
the device is still busy with the high voltage cycle, then
no ACK will be returned. If the device has completed
the write operation, an ACK will be returned and the
host can then proceed with the read or write operation.
Refer to Flow 1.
OPERATION
A WRITE?
YES
ISSUE BYTE
ADDRESS
ISSUE STOP
PROCEED
PROCEED
2783 ILL F09
Figure 6. Page Write
S
T
S
T
O
P
SLAVE
ADDRESS
A
R
T
BUS ACTIVITY:
MASTER
BYTE ADDRESS (n)
DATA n
DATA n+1
DATA n+31
SDA LINE
S
P
A
C
K
A
C
K
A
C
K
A
C
K
A
C
K
BUS ACTIVITY:
X24645
2783 ILL F10.2
6
XICOR [ XICOR INC. ]
