Rainbow Electronics MAX6900 - Manual (Page 6)

MAX6900
I
2
C-Compatible RTC in a TDFN
6 _______________________________________________________________________________________
After the Start condition occurs, 1 bit of data is trans-
ferred for each clock pulse. The data on SDA must
remain stable during the high portion of the clock pulse
as changes in data during this time are interpreted as a
control signal (Figure 5). Any time a start condition
occurs, the Slave ID must follow immediately, regard-
less of completion of the previous data transfer.
Before any data is transmitted on the I 2 C-bus-compati-
ble serial interface, the device that is expected to
respond is addressed first. The first byte sent after the
start (S) procedure is the Address byte or 7-bit Slave
ID. The MAX6900 acts as a slave transmitter/receiver.
Therefore, SCL is only an input clock signal and SDA is
a bidirectional data line. The Slave Address for the
MAX6900 is shown in Figure 6.
DATA LINE
STABLE;
DATA VALID
CHANGE
OF DATA
ALLOWED
SDA
SCL
Figure 5. I 2 C Bus Bit Transfer
RD/W
BIT 0 BIT 7
0 0 0 0 1 0 1
Figure 6. I 2 C Bus Slave Address or 7-Bit Slave ID
SDA
SCL
SLAVE
RECEIVER
SLAVE
TRANSMITTER/
RECEIVER
MASTER
TRANSMITTER
MASTER
TRANSMITTER/
RECEIVER
MASTER
TRANSMITTER/
RECEIVER
Figure 3. I 2 C Bus System Configuration
START CONDITION STOP CONDITION
P S
SDA
SCL
SDA
SCL
Figure 4. I 2 C Bus Start and Stop Conditions