3.
Device Operation
CLOCK and DATA TRANSITIONS:
The SDA pin is normally pulled high with an external device. Data on the SDA
pin may change only during SCL low time periods (see
Data changes during SCL high
periods will indicate a start or stop condition as defined below.
START CONDITION:
A high-to-low transition of SDA with SCL high is a start condition which must precede any
other command (see
STOP CONDITION:
A low-to-high transition of SDA with SCL high is a stop condition. After a read sequence, the
stop command will place the EEPROM in a standby power mode (see
ACKNOWLEDGE:
All addresses and data words are serially transmitted to and from the EEPROM in 8-bit words.
The EEPROM sends a zero to acknowledge that it has received each word. This happens during the ninth clock
cycle.
STANDBY MODE:
The Atmel
®
AT24C02C features a low-power standby mode which is enabled: (a) upon power-
up and (b) after the receipt of the STOP bit and the completion of any internal operations.
2-Wire Software Reset:
After an interruption in protocol, power loss or system reset, any 2-wire part can be reset
by following these steps: (a) Create a start bit condition, (b) clock 9 cycles, (c) create another start bit followed by
stop bit condition as shown below. The device is ready for next communication after above steps have been
completed.
Figure 3-1.
Software reset
Start bit
Dummy Clock Cycles
Start bit
Stop bit
SCL
1
2
3
8
9
SDA
6
Atmel AT24C02C
8700D–SEEPR–8/10
ATMEL [ ATMEL CORPORATION ]
