# BUS - BIU = Bus Interface Unit, connected to [[microcontroller]] to manage `ADDR`, `DATA`, `CTRL` buses. - Shared Bus types - Master/Slave - [[spi|SPI]], [[i2c|I2C]], Bluetooth, cellular - Distributed Coordination Function (DCF) - Ethernet (CSMA/CD), WiFi (CSMA/CA) - Arbitration style - [[can|CAN]], deterministic access