MCP79411 datasheet(36/60 Pages) MICROCHIP

36 / 60 page

MCP79410/MCP79411/MCP79412

DS20002266E-page 36

 2010-2013 Microchip Technology Inc.

9.1.3

ACKNOWLEDGE POLLING

Since the device will not acknowledge an EEPROM

command during an EEPROM 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. ACK polling can 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, then the Start bit and control byte must be

resent. If the cycle is complete, then the device will

return the ACK, and the master can then proceed with

the next Read or Write command. See Figure 9-4 for

the flow diagram.

FIGURE 9-4:

ACKNOWLEDGE

POLLING FLOW

Send

EE Write Command

Send Stop

Condition to

Initiate EE Write Cycle

Send Start

Send Control Byte

with R/W = 0

Did Device

Acknowledge

(ACK = 0)?

Operation

NO*

YES

Note*: For added system robustness, implement

time-out checking to avoid a potential infinite loop.

Note:

For added systems robustness, it is

recommended that time-out functionality

be implemented in the acknowledge poll-

ing routine to avoid potentially hanging the

system by entering an infinite loop. This

can easily be done by designing in a

maximum number of loops the routine will

execute, or through the use of a hardware

timer

If a time out occurs, polling should be

aborted by sending a Stop condition. A

user-generated error-handling routine can

then be called, allowing the system to

recover in a manner appropriate for the

application.

MCP79411 Datasheet(PDF) 36 Page - Microchip Technology

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