Table 3. 2-wire interface address map – Rainbow Electronics MAX7360 User Manual

Page 14

C-Interfaced Key-Switch Controller and LED

Driver/GPIOs with Integrated ESD Protection

MAX7360

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is required on SDA. The MAX7360’s SCL line operates

only as an input. A pullup resistor is required on SCL if

there are multiple masters on the 2-wire interface, or if

the master in a single-master system has an open-drain

SCL output.
Each transmission consists of a START condition (Figure

3) sent by a master, followed by the MAX7360 7-bit slave

address plus R/W bit, a register address byte, one or

more data bytes, and finally, a STOP condition.

START and STOP Conditions

Both SCL and SDA remain high when the interface is not

busy. A master signals the beginning of a transmission

with a START (S) condition by transitioning SDA from

high to low while SCL is high. When the master has

finished communicating with the slave, it issues a STOP

(P) condition by transitioning SDA from low to high while
SCL is high. The bus is then free for another transmission.

Bit Transfer

One data bit is transferred during each clock pulse

(Figure 4). The data on SDA must remain stable while

SCL is high.

Acknowledge

The acknowledge bit is a clocked 9th bit (Figure 4), which

the recipient uses to handshake receipt of each byte of

data. Thus, each byte transferred effectively requires

9 bits. The master generates the 9th clock pulse, and

the recipient pulls down SDA during the acknowledge

clock pulse; therefore, the SDA line is stable low during

the high period of the clock pulse. When the master is

transmitting to the MAX7360, the MAX7360 generates the

acknowledge bit because the MAX7360 is the recipient.

When the MAX7360 is transmitting to the master, the

master generates the acknowledge bit because the

master is the recipient.

Figure 3. START and STOP Conditions

Figure 4. Bit Transfer

Table 3. 2-Wire Interface Address Map

PIN AD0

DEVICE ADDRESS

GND

R/W

SDA

R/W

SCL

R/W

SDA

SCL

START

CONDITION

STOP

CONDITION

SDA

SCL

DATA LINE STABLE;

DATA VALID

CHANGE OF DATA

ALLOWED