AT24C1024SC_14 Datasheet, PDF (10/14 Pages) ATMEL Corporation – Schmitt Triggers, Filtered Inputs for Noise Suppression

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 and 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.
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.
The microcontroller does not respond with an input “0” but does generate a following
stop condition (see Figure 11).
Figure 11. Current Address Read
S
T
R
S
A
E
T
R
DEVICE
A
O
T
ADDRESS
D
P
SDA LINE
Figure 12. Random Read
M
LRA
DATA
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. The microcontroller does not respond
with a “0” but does generate a following stop condition (see Figure 12).
S
W
S
T
R
1st, 2nd WORD
T
A
I
ADDRESS n
A
R
DEVICE
T
R
T
ADDRESS
E
T
SDA LINE
M
S
B
P₀ R A
/C
WK
LA
SC
BK
DEVICE
ADDRESS
0
R
E
A
D
A
C
K
DUMMY WRITE
S
T
O
P
DATA n
N
O
A
C
K
10 AT24C1024SC
5045A–SEEPR–04/04