DIA1412

Version 1.0, Jul 2024

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protocol, and the register contents will remain unaffected. Stretching of the SMCLK signal is supported if the

timing is managed by other SMBus components.

11.2. SMBus protocol

The DIA1412 supports various kind of byte protocols: Send bite, Read byte, Write byte, Receive byte and Alert

response address as valid protocols.

(1) Write byte: Writing one byte of data to the registers.

(2) Read byte: Reading one byte of data from the registers.

(3) Send byte: Setting the internal address register pointer to the correct address location. Noted that no data is

transferred during the Send byte protocol.

(4) Receive byte: Reading data from a register when the internal register address pointer is at the correct

location via Send byte. This is used for consecutive reads of the same register.

(5) Alert response address: the

_____

ALERT pin output can be interpreted as interrupt or as an SMBus Alert by the

host. When the

_____

ALERT pin is asserted, the host will send the Alert Response Address (ARA) to the general

address of 0001_100xb. The DIA1412 will respond to the ARA in two steps: send the slave address of DIA1412.

Then the channel mask bit will be set and the

_____

ALERT pin will be deasserted.

Write Byte Protocol

Start

Slave

Address

WR

ACK (1)

Register

Address

ACK (1)

Register

Data

ACK (1)

Stop

1 -> 0

YYYY_YYY

0

0

XXh

0

XXh

0

0 ->1

Read Byte Protocol

Start

Slave

Address

WR

ACK (1)

Register

Address

ACK (1)

Start

Slave

Address

RD

ACK (1)

Register

Data (1)

NACK

Stop

1 -> 0

YYYY_

YYY

0

0

XXh

0

1 -> 0

YYYY_

YYY

1

0

XXh

1

0 ->1

Send Byte Protocol

Start

Slave Address

WR

ACK (1)

Register Address

ACK (1)

Stop

1 -> 0

YYYY_YYY

0

0

XXh

0

0 ->1

Receive Byte Protocol

Start

Slave Address

RD

ACK (1)

Register Data (1)

NACK

Stop

1 -> 0

YYYY_YYY

1

0

XXh

1

0 ->1

Alert Response Address Protocol

Start

Alert Response

Address

RD

ACK (1)

Device Address (1)

NACK

Stop

1 -> 0

0001_100

1

0

YYYY_YYY

1

0 ->1

Note:

(1) Date is sent to the host.