SI7015-A20 Datasheet, PDF (23/39 Pages) Silicon Laboratories – DIGITAL IC HUMIDITY AND TEMPERATURE SENSOR

Si7015-A20
5.2. I²C Operation
The format of the address byte is shown in Table 16.
Table 16. I²C Slave Address Byte
A6
A5
A4
A3
A2
A1
1
0
0
0
0
0
A0
R/W
0
1/0
5.2.1. I²C Write Operation
To write to a register on the Si7015, the master should issue a start command (S) followed by the slave address,
0x40. The slave address is followed by a 0 to indicate that the operation is a write. Upon recognizing its slave
address, the Si7015 issues an acknowledge (A) by pulling the SDA line low for the high duration of the ninth SCL
cycle. The next byte the master places on the bus is the register address pointer, selecting the register on the
Si7015 to which the data should be transferred. After the Si7015 acknowledges this byte, the master places a data
byte on the bus. This byte will be written to the register selected by the address pointer. The Si7015 will
acknowledge the data byte, after which the master issues a Stop command (P). See Table 17.
Master Slave
Table 17. I²C Write Sequence
Sequence to Write to a Register
S Slave Address W A Address Pointer A Register Data A P
Sequence to Start a Relative Humidity Conversion
S
0x40
0A
0x03
A
0x01
AP
Sequence to Start a Temperature Conversion
S
0x40
0A
0x03
A
0x11
AP
Rev. 1.0
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