X1286V14IZ INTERSIL [Intersil Corporation], X1286V14IZ Datasheet - Page 18

• Manufacturer Part Number: X1286V14IZ
• Description: Intersil Real Time Clock/Calendar/CPU Supervisor with EEPROM
• Manufacturer: INTERSIL [Intersil Corporation]

Acknowledge Polling
Disabling of the inputs during nonvolatile write cycles
can be used to take advantage of the typical 5mS write
cycle time. Once the stop condition is issued to indi-
cate the end of the master’s byte load operation, the
X1286 initiates the internal nonvolatile write cycle.
Acknowledge polling can begin immediately. To do
this, the master issues a start condition followed by the
Slave Address Byte for a write or read operation. If the
X1286 is still busy with the nonvolatile write cycle then
no ACK will be returned. When the X1286 has com-
pleted the write operation, an ACK is returned and the
host can proceed with the read or write operation.
Refer to the flow chart in Figure 12.
Read Operations
There are three basic read operations: Current
Address Read, Random Read, and Sequential Read.
Current Address Read
Internally the X1286 contains an address counter that
maintains the address of the last word read incre-
mented by one. Therefore, if the last read was to
address n, the next read operation would access data
from address n+1. On power-up, the sixteen bit
address is initialized to 0h. In this way, a current
address read immediately after the power-onpower-on
reset can download the entire contents of memory
starting at the first location.Upon receipt of the Slave
Address Byte with the R/W bit set to one, the X1286
issues an acknowledge, then transmits eight data bits.
The master terminates the read operation by not
responding with an acknowledge during the ninth
Figure 11. Current Address Read Sequence
18
Signals from
the Master
SDA Bus
Signals from
the Slave
S
a
t
r
t
1
Address
X1286
Slave
1
1
1
clock and issuing a stop condition. Refer to Figure 11
for the address, acknowledge, and data transfer
sequence.
Figure 12. Acknowledge Polling Sequence
1
C
A
K
Data
Cycle complete. Continue
command sequence?
Byte load completed
Enter ACK Polling
by issuing STOP.
Continue normal
(Read or Write)
nonvolatile write
Read or Write
Issue START
Address Byte
Issue Slave
PROCEED
command
returned?
sequence
ACK
S
YES
YES
o
p
t
NO
NO
Issue STOP
Issue STOP
April 14, 2006
FN8101.1