© 2007 Microchip Technology Inc.

DS21189L-page 9

24AA64/24LC64/24FC64

5.0

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

command has been issued from the master, the device

initiates the internally-timed write cycle and ACK polling

can then be initiated immediately. This involves the

master sending a Start condition followed by the control

byte for a Write command (R/W = 0). If the device is still

busy with the write cycle, then no ACK will be returned.

If no ACK is returned, the Start bit and control byte must

be re-sent. If the cycle is complete, the device will

return the ACK and the master can then proceed with

the next Read or Write command. See Figure 5-1 for a

flow diagram of this operation.

FIGURE 5-1:

ACKNOWLEDGE POLLING

FLOW

Send

Write Command

Send Stop

Condition to

Initiate Write Cycle

Send Start

Send Control Byte

with R/W = 0

Did Device

Acknowledge

(ACK = 0)?

Next

Operation

No

Yes