The Input Plug is a small board containing a CD4067 16-channel analog multiplexer plus a dedicated ATtiny microcontroller to take care of channel selection. It allows you to connect up to 16 analog inputs to a single AIO pin on any port. There is an “InputPlug” class in the Ports library to interface with this board and perform the channel selection.
This board can also be used as 16-channel digital input multiplexer, and even for digital outputs or PWM – with the restriction than a channel goes into high-impedance mode when not selected (there is no latching or buffering).
The Assembled Input Plug comes with the SMD-sized CD4067 and ATTiny chips and decoupling capacitor already soldered onto the board. This plug has 16 I/O channels, available via three 6-pin headers. Headers for this and all other JeeLabs plugs can be found here (straight) and here (right angle).
The PCB Only version contains just the printed circuit board for the Input Plug. No parts, no headers.