PCT2202

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© NXP Semiconductors N.V. 2015. All rights reserved.

Product data sheet

Rev. 1.1 — 14 August 2015

13 of 30

NXP Semiconductors

PCT2202

8.2 Serial bus address

To communicate with the PCT2202, the master must first address slave devices via a

slave address byte. The slave address byte consists of seven address bits, and a

direction bit indicating the intent of executing a read or write operation.

The PCT2202 features an address pin to allow up to four devices to be addressed on a

single bus. Table 15 describes the pin logic levels used to properly connect up to four

devices.

8.3 Write/read operation

Accessing a particular register on the PCT2202 is accomplished by writing the appropriate

value to the Pointer register. The value for the Pointer Register is the first byte transferred

after the slave address byte with the R/W bit LOW. Every write operation to the PCT2202

requires a value for the Pointer register (see Figure 15).

When reading from the PCT2202, the last value stored in the Pointer register by a write

operation is used to determine which register is read by a read operation. To change the

register pointer for a read operation, a new value must be written to the Pointer register.

This action is accomplished by issuing a slave address byte with the R/W bit LOW,

followed by the Pointer register byte. No additional data are required. The master can then

generate a START condition and send the slave address byte with the R/W bit HIGH to

initiate the read command. See Figure 16 for details of this sequence. If repeated reads

from the same register are desired, it is not necessary to continually send the Pointer

register bytes, because the PCT2202 remembers the Pointer register value until it is

changed by the next write operation.

Note that register bytes are sent with the most significant byte first, followed by the least

significant byte.

8.4 Slave mode operations

The PCT2202 can operate as a slave receiver or slave transmitter. As a slave device, the

PCT2202 never drives the SCL line — it is an input only.

8.4.1 Slave receiver mode

The first byte transmitted by the master is the slave address, with the R/W bit LOW. The

PCT2202 then acknowledges reception of a valid address. The next byte transmitted by

the master is the Pointer register. The PCT2202 then acknowledges reception of the

Pointer register byte. The next byte or bytes are written to the register addressed by the

Pointer register. The PCT2202 acknowledges reception of each data byte. The master

can terminate data transfer by generating a START or STOP condition.

Table 15.

Address pin (ADD0) and slave addresses

Device two-wire address

A0 pin connection

1001 000

GND

1001 001

1001 010

SDA

1001 011

SCL