Need more pins on your Arduino? Maybe an I/O expander is what you need. These chips use the 2-pins of the i2c port to give 8 more in/out pins. You can have up to 8 of them share the same two pins for up to 64 additional pins! The trade off is speed (its about 50x slower to go through the expander than direct) and memory (the library takes up both RAM and flash). We wrote a handy library with examples of reading, writing and setting pullups for the inexpensive and easy-to-breadboard MCP23008.
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, or even use Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for MakeCode, CircuitPython, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.
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