This is a convenient 16-channel analog/digital multiplexing/demultiplexing breakout board based on the CD74HC4067 chip. The chip functions like a rotary switch, internally routing a common pin (labeled “SIG” on the board) to one of 16 channel pins (C0–C15). It supports both digital and analog signals, with voltage levels limited to the range between ground and VCC. Signal flow is bidirectional. Control is achieved by connecting four digital outputs to the address select pins (S0–S3) and sending the corresponding 4-bit binary address to select the desired channel (refer to the datasheet for addressing details). This enables connection of up to 16 sensors using only five microcontroller pins. Since the multiplexer/demultiplexer handles digital signals, it can be used to route TTL-level serial data to multiple devices—for example, connecting the TX pins of up to 16 devices to a single RX pin on a microcontroller, allowing selection of any one device for communication. For bidirectional communication, a second board can be added to route the microcontroller’s TX line to the RX lines of the 16 devices. Multiple boards can also support similar configurations for protocols such as I2C and SPI. The internal switches are bidirectional, operate within the ground-to-VCC voltage range, feature low on-resistance and low off-leakage current, and implement break-before-make switching to prevent crosstalk. The board exposes the chip’s enable pin; driving it high disconnects all channels (common pin isolated). Product Name: CD74HC4067 High-Speed CMOS Analog Multiplexer – 16-Channel Analog Multiplexer Function: 16-channel analog signal switch using CD74HC4067 Analog Signal Inputs: C0–C15 (16 channels) Analog Output: SIG Channel Selection Control: S0–S3 Material: PCB Dimensions: 4.2 x 2.1 cm Color: Blue Package Contents: 1 x CD74HC4067 16-Channel Analog Multiplexer Breakout Board Note: Actual product appearance may vary slightly due to lighting conditions.