CJMCU-9548 TCA9548A I2C 8 Channel Multiplexer Development Board Sensor Module For Arduino [ElectricA]

Specification and Features :
1-to-8 Bidirectional Translating Switches.
Supports Hot Insertion.
Low Standby Current.
Active-Low Reset Input.
Power Up With All Switch Channels Deselected.
I2C Bus and SMBus Compatible.
5-V Tolerant Inputs.
Latch-Up Performance Exceeds 100 mA Per JESD 78, Class II.

Pin Description : 
Power Pins:
Vin – 5V
GND – common ground for power and logic.

I2C Control-Side pins : 
SCL – this is the I2C clock pin for the chip itself, connect to microcontrollers I2C clock line.
SDA – this is the I2C data pin for the chip itself, connect to microcontrollers I2C data line.
RST – this is the reset pin, for resetting the multiplexer chip. Pulled high by default, connect to ground to reset
A0 A1 A2 – these are the address selection pins for the multiplexer. By default, the multiplexer is at address 0x70 and these three pins are pulled low. Connect them to Vin to set the address to 0x71 – 0x77.
A0 is the lowest-significant bit (if it is pulled high, it will increase the address by 1).
A1 is the 2nd-lowest-significant bit (if it is pulled high, it will increase the address by 2).
A2 is the 3rd-lowest-significant bit (if it is pulled high, it will increase the address by 4).
SDx and SCx:  
There are 8 sets of SDx and SCx pins, from SD0/SC0 to SD7/SC7. These are the multiplexed pins. Each one is a completely separate I2C bus set. 
Have 8 I2C devices with identical addresses, as long as they are on one I2C bus each.
These pins do not have any pullups installed.

I2C connections are awesome to use with for Arduino or similar microcontroller boards. Controlling a bunch of devices by using only two pins is really great, but there is a small problem. Some I2C boards have fixed I2C addresses. Sadly you cannot use more than one I2C device together if they have the same I2C address.

So what happens if you find a great sensor operated over I2C and you want to use more than one of that sensor. The best solution is TCA9548A I2C Multiplexer which lets you use up to 8 devices over I2C which have the same address.

Using TCA9548A I2C Multiplexer is pretty simple. The multiplexer itself is operated on I2C line with the default address 0x70 (the address is selectable between 0x70 and 0x77). After wiring the SDA and SCL pins of your microcontroller to the multiplexer, you just write a byte, selecting the multiplexed output line and the rest of the I2C packets are set to send to that line. In theory you can use 8 of these multiplexers on the same address and use 64 devices having the same I2C address.

The TCA9548A chip onboard is 3,3V and 5V compliant, so it can be used with both logical levels.