24LCS61/62

© 1997 Microchip Technology Inc.

Preliminary

DS21226A-page 11

7.0

ACKNOWLEDGE POLLING

Since the device will not acknowledge during a write

cycle, this can be used to determine when the cycle is

complete (this feature can be used to maximize bus

throughput). Once the stop condition for a write com-

mand has been issued from the master, the device ini-

tiates the internally timed write cycle. ACK polling can

be initiated immediately. This involves the master send-

ing a start condition followed by the control byte for a

write command and then sending the Device ID byte for

that particular device. If the device is still busy with the

write cycle, then no ACK will be returned after the

Device ID byte. If no ACK is returned, then the start bit,

control byte and ID byte must be re-sent. If the cycle is

complete, then the device will return the ACK and the

master can then proceed with the next command. See

Figure 7-1 for flow diagram.

FIGURE 7-1:

ACKNOWLEDGE POLLING

FLOW

Send

Write Command

Send Stop

Condition to

Initiate Write Cycle

Send Start

Did Device

Acknowledge

(ACK = 0)?

Next

Operation

NO

YES

Send Control byte and

Device ID byte

Device ID