5

I²C interface

5.1

Read and write operations

The I²C interface is used to configure, control and read the operation status of the device. It is compatible with the

Philips I²C BUS® (version 2.1). The I²C is a slave serial interface based on two signals:

•

SCL - serial clock line: input clock used to shift data

•

SDA - serial data line: input/output bidirectional data transfers

A filter rejects the potential spikes on the bus data line to preserve data integrity.

The bidirectional data line supports transfers up to 400 Kbit/s (fast mode). The data are shifted to and from the

chip on the SDA line, MSB first.

The first bit must be high (START) followed by the 7-bit device address and the read/write control bit.

Two 7-bit device addresses are available for the STUSB1702 thanks to external programming of DevADDR0

through ADDR0 pin setting, i.e. 0x28 or 0x29. This allows two STUSB1702 devices to be connected on the same

I²C bus.

Table 8. Device address format

Bit7

Bit6

Bit5

Bit4

Bit3

Bit2

Bit1

Bit0

DevADDR6

DevADDR5

DevADDR4

DevADDR3

DevADDR2

DevADDR1

DevADDR0

R/W

0

1

0

1

0

0

ADDR0

0/1

Table 9. Register address format

Bit7

Bit6

Bit5

Bit4

Bit3

Bit2

Bit1

Bit0

RegADDR7

RegADDR6

RegADDR5

RegADDR4

RegADDR3

RegADDR2

RegADDR1

RegADDR0

Table 10. Register data format

Bit7

Bit6

Bit5

Bit4

Bit3

Bit2

Bit1

Bit0

DATA7

DATA6

DATA5

DATA4

DATA3

DATA2

DATA1

DATA0

Figure 5. Read operation

Address

n+1

Start bit = SDA falling when SCL= 1

Stop bit = SDA rising when SCL= 1

Restart bit = start after a start

Acknowledge = SDA forced low during a SCL clock

Master

Slave

Address

n+2

Start

Device addr

7 bits

W A Reg address

8 bits

A Restart

Device addr

7 bits

R A

Reg data

8 bits

A Reg data

8 bits

A

Reg data

8 bits

A

Stop

STUSB1702

I²C interface

DS12664 - Rev 1

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