Si53xx-RM

7.13. I2C Serial Microprocessor Interface

When configured in I2C control mode (CMODE = L), the control interface to the device is a 2-wire bus for bidirectional communication. The bus consists of a bidirectional serial data line (SDA) and a serial clock input (SCL). Both lines must be connected to the positive supply via an external pull-up. In addition, an output interrupt (INT) is provided with selectable active polarity (determined by INT_POL bit). Fast mode operation is supported for transfer rates up to 400 kbps as specified in the I2C-Bus Specification standard. To provide bus address flexibility, three pins (A[2:0]) are available to customize the LSBs of the device address. The complete bus address for the device is as follows:

1 1 0 1 A[2] A[1] A[0] R/W.

Figure 34 shows the command format for both read and write access. Data is always sent MSB first. The timing specifications and timing diagram for the I2C bus can be found in the I2C-Bus Specification standard (fast mode operation) (See: http://www.standardics.nxp.com/literature/books/i2c/pdf/i2c.bus.specification.pdf).

The maximum I2C clock speed is 400 kHz.

S

Slave Address

0 A

Byte

Address

A Data

A Data

A P

Write Command

S

Slave Address

0 A

Byte

Address

A S Slave Address 1 A Data

A Data A P

Read Command

–address auto incremented after each data read or write

(this can be two separate transactions)

From master to slave

A – Acknowledge (SDA LOW)

 

S– START condition

From slave to master

P– STOP condition

Figure 34. I2C Command Format

In Figure 35, the value 68 is seven bits. The sequence of the example is: Write register 00 with the value 0xAA; then, read register 00. Note that 0 = Write = W, and 1 = Read = R.

 

S

Slave Address

0

A

Byte Address

 

A

 

Data

A

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

68

W

 

00

 

 

 

AA

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Write Command

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

S

Slave Address

0

A

Byte Address

 

A

S

Slave Address 1

A Data

 

 

 

 

 

 

 

 

 

 

 

 

 

68

W

00

68

R

AA

Read Command

Figure 35. I2C Example

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Silicon Laboratories SI5316, SI5369, SI5365, SI5366, SI5367 manual 13. I2C Serial Microprocessor Interface, I2C Command Format