24LC21-/P MICROCHIP [Microchip Technology], 24LC21-/P Datasheet - Page 10

• Manufacturer Part Number: 24LC21-/P
• Description: 1K 2.5V Dual Mode I2C Serial EEPROM
• Manufacturer: MICROCHIP [Microchip Technology]

24LC21
5.0
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. 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 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 5-1 for the flow
diagram.
FIGURE 5-1:
DS21095J-page 10
ACKNOWLEDGE POLLING
Initiate Write Cycle
Send Control Byte
Write Command
with R/W = 0
Acknowledge
Condition to
Send Stop
(ACK = 0)?
Did Device
Send Start
Operation
Send
Next
ACKNOWLEDGE
POLLING FLOW
Yes
No
6.0
When using the 24LC21 in the Bidirectional mode, the
V
Setting V
setting V
array. Connecting the V
24LC21 to operate as a serial ROM, although this
configuration would prevent using the device in the
Transmit-only mode.
CLK
pin operates as the write-protect control pin.
CLK
WRITE PROTECTION
CLK
low prevents writing to any location in the
high allows normal write operations, while
CLK
 2004 Microchip Technology Inc.
pin to V
SS
would allow the