This stackable shield is designed to mount on the NodeMCU Wireless Development Board found HERE and provides 16 additional digital IO ports.

NOTE: This shield is not physically compatible with any other micro-controller, including Arduino boards.

It is based on the MCP23017 chip DATASHEET and is compatible with the Adafruit MCP20317 Arduino library found HERE.

The shield has 2 LEDS and a momentary tactile switch for testing or signaling and has 2 interrupt lines that can be jumpered to NodeMCU pins to allow for interrupt-on-change functionality. The LEDs can be disconnected from the IO ports via slide switches.

A 90-degree triple-row connector on the end breaks out every port and also provides a convenient pin for +3.3v and GND for each port. It can sink or source up to 20ma of current per pin, so it can drive LEDs and other such devices.

NOTE2: Make sure to use a resistor when syncing or sourcing current to keep the current under 20ma or you can burn out the pin!

It comes with a stackable header and is addressable via solder-jumper to allow you to stack up to 8 shields for a total of 128 digital IO ports!

This board requires some light soldering to mount headers and connectors with the SMD components pre-assembled.

Features

• 16-Bit Remote Bidirectional I/O Port
• I/O pins default to input
• High-Speed I2C Control Interface supports 100Khz/400Khz/1.7MHz
• Three Hardware Address Pins to allow up to eight shields to be stacked
• Two interrupt output pins configurable as active-high, active-low or open-drain
• INTA and INTB can be configured to Operate independently or together
• Configurable interrupt source: Interrupt-on-change from configured register defaults or pin changes
• Polarity inversion register to configure the polarity of the input port data
• Low Standby Current: 1 µA (max.)