M24C01(2000) データシートの表示（PDF） - STMicroelectronics
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M24C01 Datasheet PDF : 20 Pages
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M24C16, M24C08, M24C04, M24C02, M24C01
Figure 4. I2C Bus Protocol
SCL
SDA
START
CONDITION
SDA
SDA
INPUT CHANGE
STOP
CONDITION
SCL
SDA
1
2
3
MSB
START
CONDITION
7
8
9
ACK
SCL
1
2
3
7
8
9
SDA
MSB
ACK
STOP
CONDITION
AI00792
disabled – the device will not respond to any
command. In the same way, when VCC drops from
the operating voltage, below the POR threshold
value, all operations are disabled and the device
will not respond to any command. A stable and
valid VCC must be applied before applying any
logic signal.
SIGNAL DESCRIPTION
Serial Clock (SCL)
The SCL input pin is used to strobe all data in and
out of the memory. In applications where this line
is used by slaves to synchronize the bus to a
slower clock, the master must have an open drain
output, and a pull-up resistor must be connected
from the SCL line to VCC. (Figure 3 indicates how
the value of the pull-up resistor can be calculated).
In most applications, though, this method of
synchronization is not employed, and so the pull-
up resistor is not necessary, provided that the
master has a push-pull (rather than open drain)
output.
Serial Data (SDA)
The SDA pin is bi-directional, and is used to
transfer data in or out of the memory. It is an open
drain output that may be wire-OR’ed with other
open drain or open collector signals on the bus. A
pull up resistor must be connected from the SDA
bus to VCC. (Figure 3 indicates how the value of
the pull-up resistor can be calculated).
Chip Enable (E2, E1, E0)
These chip enable inputs are used to set the value
that is to be looked for on the three least significant
bits (b3, b2, b1) of the 7-bit device select code (but
see the description of memory addressing, on
page 6, for more details). These inputs may be
driven dynamically or tied to VCC or VSS to
establish the device select code (but note that the
VIL and VIH levels for the inputs are CMOS
compatible, not TTL compatible).
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