Easily add a few more I/O or A/D channels to your project through I2C Do complex tasks with a few simple calls to the API available for download through the IDE Library Manager Many support videos and extensive documentation available online. See the User Guide pdf in the "Product guides and documents" at the bottom of this lisiting 3 Input/Output and 1 Input Only pin on each chip. Each pin can be assigned a specific function such as Servo, Quadrature Encoder, A/D conversion, UART Bridge Use all 4 chips together, or in 4 different projects. 100nF capacitors included. Uncut decal strip with 8 decals included. Upgradable Open Source Firmware available on GitHub.