This Is A Very Convenient 16-Channel Analog/Digital Multiplexing/Demultiplexing CD74HC4067 Breakout Board. This Chip Acts Like A Rotary Switch - It Internally Routes A Common Pin (Com In The Schematic, Sig On The Board) To One Of 16 Channel Pins (Chanxx). It Can Handle Digital And Analog Signals (The Voltage Cannot Be Higher Than VCC), And It Can Be Connected In Any Direction. To Control It, Connect The 4 Digital Outputs To The Chip'S Address Select Pins (S0-S3) And Send It The Binary Address Of The Channel You Want (See Datasheet For Details). This Allows You To Connect Up To 16 Sensors To Your System Using 5 Pins! Since Mux/Demux Can Also Handle Digital Signals, You Can Use It To Transmit Ttl-Level Serial Data To Multiple Devices. For Example, You Can Use It To Connect The Tx Pins Of 16 Devices To One Rx Pin On A Microcontroller. You Can Then Choose Any Of The 16 Devices To Listen To. If You Want Two-Way Communication, You Can Add A Second Board To Route The Tx Line Of The Microcontroller To The Rx Line Of The 16 Devices. By Using Multiple Boards, You Can Create Similar Arrangements For I2c, SPI, ETC. The Internal Switch Is Bidirectional, Supports Voltage Between Ground And Vcc, Has Low "On" Resistance And Low "OFF" Leakage, And Performs "Break Before Make" Switching To Prevent Crosstalk. The Board Also Breaks Out The Chip'S "Enable" Pin, Which, When Driven High, Will Completely Disconnect The Common Pin (All Switches "Off"). Description: 1. Product Name: CD74HC4067 High-Speed CMOS Analog Multiplexer 16-Channel Analog Multiplexer 2. Function: 16-Channel Analog Signal Switch Using Cd74hc4067 3. Analog Signal Input: C0-C15 16 Channels 4. Analog Output: DIG 5. Channel Control: S0-S3 6. Material: PCB 7. Size: 4.2 x 2.1cm 8.Color: Blue Package Contents: 10 x Channel Analog Multiplexer