X4285 XICOR [Xicor Inc.], X4285 Datasheet - Page 10

• Manufacturer Part Number: X4285
• Description: CPU Supervisor with 128K EEPROM
• Manufacturer: XICOR [Xicor Inc.]

X4283/85 – Preliminary Information
Figure 10. Writing 12 bytes to a 64-byte page starting at location 60.
The master terminates the Data Byte loading by issuing
a stop condition, which causes the device to begin the
nonvolatile write cycle. As with the byte write operation,
all inputs are disabled until completion of the internal
write cycle. See Figure 9 for the address, acknowledge,
and data transfer sequence.
Stops and Write Modes
Stop conditions that terminate write operations must be
sent by the master after sending at least 1 full data byte
plus the subsequent ACK signal. If a stop is issued in
the middle of a data byte, or before 1 full data byte plus
its associated ACK is sent, then the device will reset
itself without performing the write. The contents of the
array will not be effected.
Acknowledge Polling
can be used to take advantage of the typical 5ms write
cycle time. Once the stop condition is issued to indicate
the end of the master’s byte load operation, the device
initiates the internal nonvolatile cycle. Acknowledge
polling can be initiated immediately. To do this, 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 nonvolatile cycle then no ACK will
be returned. If the device has completed the write oper-
ation, an ACK will be returned and the host can then
proceed with the read or write operation. Refer to the
flow chart in Figure 11.
REV 1.17 11/27/00
The disabling of the inputs during nonvolatile cycles
8 Bytes
Address
= 7
Address Pointer
Ends Here
Addr = 8
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Figure 11. Acknowledge Polling Sequence
Address
60
Command Sequence?
Command Sequence
Byte Load Completed
Issue Slave Address
Byte (Read or Write)
Complete. Continue
Nonvolatile Cycle
Enter ACK Polling
Continue Normal
by Issuing STOP.
Read or Write
Issue START
PROCEED
returned?
ACK
Characteristics subject to change without notice.
4 Bytes
YES
YES
Address
n-1
NO
NO
Issue STOP
Issue STOP
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