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AS6204

Register Description

Datasheet

• PUBLIC

DS000628

• v4-00 • 2021-Oct-18

36

│ 24

6.3.4

Read/Write Operation

In order to access an internal data register, the index register must be written in advance. This register

contains the actual register address and selects the appropriate register for an access. A typical

transfer consists of the transmission of the slave address with a write operation indication, followed by

the transmission of the register address and is finalized with the actual register content data transfer.

This implies that every write operation to the temperature sensor device requires a value for the index

register prior to the transmission of the actual register data.

The index register defines the register address for both the write and read operation. Consequently, if

a read operation is executed, the register address is taken from the index register, which was defined

from the last write operation.

If a different register needs to be read, the index register has to be written in advance to define the

new register address. This is accomplished by transmitting the slave address with a low R/W bit,

followed by the new content of the index register. Subsequently, the master provokes a START

condition on the bus and transmits the slave address with a high R/W bit in order to initiate a read

operation.

Since the index register always keeps its last value, reads can be executed repetitively on the same

register.

Similarly, to the byte transfer where the MSB is transmitted first, a two-byte transfer executes the

transfer of a 16-bit word whereas the MSB byte is always transmitted first.

6.3.5

Slave Operation

The device employs a slave functionality only (slave transmitter and slave receiver) and cannot

operate as a bus master. Consequently, the device never actively drives the SCL line.

6.3.6

Slave Receiver Mode

The master device invokes any transmission by transmitting the slave address with a low R/W bit.

Subsequently, the slave device acknowledges the reception of the valid address by pulling the ninth

bit to a low level. Following to acknowledge, the master transmits the content of the index register. The

slave device again acknowledges this transfer. The next data byte(s) are written to the actual data

register, which is selected by the index register while each transfer is acknowledged upon a completed

transfer by the slave device. A data transfer can be finished if the master transmits a START or a

STOP condition on the bus.

6.3.7

Slave Transmitter

The master transmits the slave address with a high R/W bit. In turn, the slave acknowledges a valid

slave address. Subsequently, the slave transmits the MSB byte of the actual selected data register by

the index register. After the MSB byte transmission, acknowledge is sent by the master. Afterwards,

the LSB byte is transmitted by the slave which is also acknowledged by the master after the