SLAS366 datasheet(21/56 Pages) TI2

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3–9

3.7.1

S2C (Start-Stop Communication)

The S2C is a write-only interface selected by programming bits D1-D0 of control register 2 to 01. The SDA input is

normally in a high state, pulled low (START bit) to start the communication, and pulled high (STOP bit) after the

transmission of the LSB. Figure 3–9 shows the timing diagram of S2C. The S2C also supports a broadcast mode in

which the same register of all devices in cascade is programmed in a single write. To use S2Cs broadcast mode,

execute the following steps:

Write 111 1000 1111 1111 after the start bit to enable the broadcast mode.

Write data to program control register as specified in with bits D14–D11 = XXXX (don’t care).

Write 111 1000 0000 0000 after the start bit to disable the broadcast mode.

D15

D14

D13

D12

D11 D10

SCL

SDA

Start Bit = 0

Stop Bit = 1

SMARTDM Device

Address

(see Table 3–1)

Address

Figure 3–9. S2C Programming

3.7.2

I2C

•

Each I2C read-from or write-to AIC15s control register is given by index register address.

•

Read/write sequence always starts with the first byte as I2C address followed by 0. During the second byte,

default/broadcast mode is set and the index register address is initialized. For write operation control

after the second byte. Now the first byte is I2C address followed by 1. From the second byte onwards, control

•

Each time read/write is performed, the index register address is incremented so that next read/write is

performed on the next control register.

•

During the first write cycle and all write cycles in the broadcast, only the device with address 0000 issues

ACK to the I2C.

I2C Write Sequence

SCL

SDA

ACK B7

ACK

Start Bit = 0

SMARTDM Device

Address

(see Table 3-1)

00000 = Default

11111 = Broadcast Mode

Index Register Address

(Index)

Control Register Data for Write

(Index)

Control Register Data for Write

(Index+1)

Programmable I2C Device Address

Set by Control Register 2

I2C

Figure 3–10. I2C Write Sequence

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