X24C00
After receipt of the control byte, the X24C00 will enter
the write mode and await the data to be written. This data
is shifted into the device on the next eight SCL clocks.
Once eight clocks have been received, the data in the
shift register will be written into the memory array. While
the write is in progress the X24C00 will not respond to
any inputs. At any time prior to clocking in the last data
bit, a stop command or a new start command will
terminate the operation. If a start command is given, the
X24C00 will reset all counters and will prepare to clock
in the next control byte. If a stop command is given, the
X24C00 will reset all counters and await the next start
command.
At the end of the write the X24C00 will automatically
reset all counters and enter the standby mode.
(Figure 4).
Read Operation
The byte read operation is initiated with a start condition.
The start condition is followed by an eight-bit control byte
which consists of a two-bit read command (1,0), four
address bits, and two “don’t care” bits. After receipt of
the control byte the X24C00 will enter the read mode and
transfer data into the shift register from the array. This
data is shifted out of the device on the next eight SCL
clocks. At the end of the read, all counters are reset and
the X24C00 will enter the standby mode. As with a write,
the read operation can be interrupted by a start or stop
condition while the command or address is being clocked
in. While clocking data out, starts or stops cannot be
generated.
During the second don’t care clock cycle, starts and
stops are ignored. The master must free the bus prior to
the end of this clock cycle to allow the X24C00 to begin
outputting data (Figures 5 and 6).
Figure 4. Write Sequence
START
0
1
A3
A2
A1
A0 XX XX D7 D6 D5 D4 D3 D2 D1 D0
3836 FHD F06
Figure 5. Read Sequence
START
1
0
A3
A2
A1
A0 XX XX D7 D6 D5 D4 D3 D2 D1 D0
3836 FHD F07
Figure 6. Read Cycle Timing
SYMBOL TABLE
WAVEFORM
INPUTS
Must be
steady
May change
from LOW
to HIGH
D7
D6
OUTPUTS
Will be
steady
Will change
from LOW
to HIGH
Will change
from HIGH
to LOW
Changing:
State Not
Known
Center Line
is High
Impedance
SCK
6
7
8
1
SDA IN
A0
XX
XX
SDA OUT
May change
from HIGH
to LOW
Don’t Care:
Changes
Allowed
N/A
3836 FHD F08
4
XICOR [ XICOR INC. ]
