A somewhat humorous app note describing the common IC interface protocols like I2C, SPI, and GPIO. Also covered are some problem with these interfaces that turn happy faces to sad.
How can an interface change a happy face to a sad face? Engineers have happy faces when an interface works properly. Sad faces indicate failure somewhere. Because interfaces between microprocessors and ICs are simple—even easy—they are often ignored until interface failure causes sad faces all around. In this article, we discuss a common SPI error that can be almost impossible to find in a large system. Links to interface tutorial information are provided for complete information. Noise as a system issue and ICs to minimize its effects are also described.