This is a 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 (CH0–CH15). It can handle both digital and analog signals (voltage must not exceed VCC) and can be connected in either direction. To control it, connect four digital outputs to the chip’s address select pins (S0–S3) and send the binary address of the desired channel (see datasheet for details). This allows you to connect up to 16 sensors to your system using only 5 pins. Since the mux/demux supports digital signals, it can also route TTL-level serial data to multiple devices. For example, you can connect the TX pins of up to 16 devices to a single RX pin on a microcontroller and select any one device to listen to. For two-way communication, add a second board to route the microcontroller’s TX line to the RX lines of the 16 devices. Multiple boards can be used to create similar configurations for I2C, SPI, and other protocols. The internal switch is bidirectional, supports voltages between ground and VCC, features low “on” resistance and low “off” leakage, and uses “break-before-make” switching to prevent crosstalk. The board also breaks out the chip’s “enable” pin—if driven high, it disconnects the common pin (all switches off). 1. Product Name: CD74HC4067 High-Speed CMOS Analog Multiplexer, 16-Channel 2. Function: 16-channel analog signal switch using CD74HC4067 3. Analog signal inputs: CH0–CH15 (16 channels) 4. Analog output: SIG 5. Channel control: S0–S3 6. Material: PCB 7. Dimensions: 4.2 x 2.1 cm 8. Color: Blue Package includes: 10 x CD74HC4067 16-channel analog multiplexer breakout boards Note: Package contains only the items listed above. Other accessories or components are not included. Lighting conditions may affect appearance.