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AS621x
Register Description
Datasheet • PUBLIC
DS000677 • v2-00 • 2020-Feb-24
36 │ 24
Figure 28:
I²C Address Select Configuration
ALERT / ADD1
Connection
ADD0 Connection
Alert
Functionality
Enabled
Device Address
(bin)
Device Address
(hex)
SCL
VSS
No
100 0100
0x44
SCL
VDD
No
100 0101
0x45
SCL
SDA
No
100 0110
0x46
SCL
SCL
No
100 0111
0x47
VSS
VSS
No
100 1000
0x48
VSS
VDD
No
100 1001
0x49
VSS
SDA
No
100 1010
0x4A
VSS
SCL
No
100 1011
0x4B
Pull up to VDD
VSS
Yes
100 1000
0x48
Pull up to VDD
VDD
Yes
100 1001
0x49
Pull up to VDD
SDA
Yes
100 1010
0x4A
Pull up to VDD
SCL
Yes
100 1011
0x4B
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.