# Appendix A: Glossary

The embedded ecosystem is full of different protocols, hardware components and vendor-specific things that use their own terms and abbreviations. This Glossary attempts to list them with pointers for understanding them better.

Term | Meaning
--- | ---
I2C | Sometimes referred to as `I² C` or Inter-IC. It is a protocol meant for hardware communication within a single integrated circuit. See i2c.info for more details
SPI | Serial Peripheral Interface
USART | Universal synchronous and asynchronous receiver-transmitter
UART | Universal asynchronous receiver-transmitter
FPU | Floating-point Unit. A 'math processor' running only operations on floating-point numbers
PAC | Peripheral Access Crate