AT24C01C_14 Datasheet, PDF (12/19 Pages) ATMEL Corporation – 2-wire Automotive Temperature Serial EEPROMs

9. Read Operations
Read operations are initiated the same way as write operations with the exception that the read/write select bit
in the device address word is set to one. There are three read operations:
 Current Address Read
 Random Address Read
 Sequential Read
Current Address Read: The internal data word address counter maintains the last address accessed during
the last read or write operation, incremented by one. This address stays valid between operations as long as the
chip power is maintained. The address roll-over during read is from the last byte of the last memory page to the
first byte of the first page. The address roll-over during write is from the last byte of the current page to the first
byte of the same page.
Once the device address with the read/write select bit set to one is clocked in and acknowledged by the
EEPROM, the current address data word is serially clocked out. To end the command, the microcontroller does
not respond with a zero but does generate a Stop condition in the subsequent clock cycle.
Figure 9-1. Current Address Read
S
T
R
S
A
E
T
R
Device
A
O
T Address
D
Data
P
SDA Line
M
LRA
N
S
S /C
O
B
BWK
A
C
K
Random Read: A Random Read requires a dummy byte write sequence to load in the data word address. Once
the device address word and data word address are clocked in and acknowledged by the EEPROM, the
microcontroller must generate another Start condition. The microcontroller now initiates a Current Address
Read by sending a device address with the read/write select bit high. The EEPROM acknowledges the device
address and serially clocks out the data word. To end the command, the microcontroller does not respond with
a zero but does generate a Stop condition in the subsequent clock cycle.
Figure 9-2. Random Read
S
W
S
T
R
T
R
S
A
I
A
E
T
R
T
R
A
O
T Device Address E
Word Address (n)
T Device Address D
Data (n)
P
SDA Line
M
RA
AM
A
N
S
/C
CS
C
O
B
WK
KB
K
A
C
K
Dummy Write
* ^{= Don’t care bit for 1K}
12 AT24C01C/02C/04C/08C Automotive [DATASHEET]
Atmel-8819B-SEEPROM-AT24C01C-02C-04C-08C-Auto-Datasheet_072014