WS281X: 3 Pin Led strips - D0, GND, +5 VCC Make Sure to give common Ground between RPI and the strip, regardless you are using an external power supply or not.

More often than not, an IoT master device uses the SPI (serial peripheral interface) and I 2 C (inter-integrated circuit) protocols to exchange data with EEPROMs or sensors that are operating in slave ...

While the Raspberry Pi has very good support for an I2C bus, a lot of very cool chips – including the in system programmer for just about every ATtiny and ATmega microcontroller – use an SPI bus.