AS6221T

Register description

Datasheet

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ALERT / ADD1

connection

ADD0 connection

Alert

functionality

enabled

Device address

(bin)

Device address

(hex)

Pull up to VDD

VSS

Yes

101 1000

0x58

Pull up to VDD

VDD

Yes

101 1001

0x59

Pull up to VDD

SDA

Yes

101 1010

0x5A

Pull up to VDD

SCL

Yes

101 1011

0x5B

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, the transfer of a 16-bit word is

executed by a two byte transfer 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

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