SI7015-A20 Datasheet, PDF (25/39 Pages) Silicon Laboratories – DIGITAL IC HUMIDITY AND TEMPERATURE SENSOR

5.2.3. Firmware Revision
The internal firmware revision can be read with the following I²C transaction:
S Slave W A
Address
0x84
A 0xB8 A S
Slave
Address
R A FWREV A NA P
The values in this field are encoded as follows:
0xFF = Firmware revision 1.0
0x20 = Firmware revision 2.0
Si7015-A20
Rev. 1.0
25