• ID: TCA9548A
• Name: 1-to-8 I2C Multiplexer Breakout
• Category: multiplexer
• Manufacturer: adafruit
• Connection: i2c
• Link: https://learn.adafruit.com/adafruit-tca9548a-1-to-8-i2c-multiplexer-breakout/overview

The TCA9548A device has eight bidirectional translating switches that can be controlled through the I2C bus. The SCL/SDA upstream pair fans out to eight downstream pairs, or channels. Any individual SCn/SDn channel or combination of channels can be selected, determined by the contents of the programmable control register.
The TCA9548A Multiplexer Breakout enables to get - up to 8 same-address I2C devices hooked up to one microcontroller - or up to 8 independent I2C buses. This multiplexer acts as a gatekeeper, shuttling the commands to the selected set of I2C pins with your command. The TCA9548A multiplexer is interesting in that it has an I2C address (0x70 by default) - and you basically send it a command to tell it which I2C multiplexed output you want to talk to, then you can address the board you want to address. You simply write a single byte with the desired multiplexed output number to that port, and bam - any future I2C packets will get sent to that port.
The TCA9548A Multiplexer provides three pins (A0-A1-A2) that enable to change its address in case 0x70 address is used by another sensor on the same bus. By connecting one of the Ax pin to Vin you change its value from 0 to 1, these values change the value of the three first bits of the address :
Address 0b01110-A2-A1-A0 No wiring A2=0 A1=0 A0=0 Address 0b01110000 0x70 A0 wired A2=0 A1=0 A0=1 Address 0b01110000 0x71 A2 wired A2=1 A1=0 A0=0 Address 0b01110100 0x74 Any address between 0x70 and 0x77 can be selected.
Tested with Adafriut TCA9548A board.