The primary topologies for SPI, I²C, CAN, UART, and USART
are fundamentally defined by how they manage device addressing and communication flow.
- SPI (Serial Peripheral Interface): Star Topology (Single Master, Multiple Slaves). The master controls individual chip select (CS) lines for each slave.
- I²C (Inter-Integrated Circuit): Bus Topology (Multi-master or Multi-slave). All devices are connected in parallel to the same two wires (SDA and SCL).
- CAN Bus (Controller Area Network): Linear Bus Topology. All nodes are connected to a single, main trunk line with two termination resistors at the ends.
- UART (Universal Asynchronous Receiver/Transmitter): Point-to-Point Topology. It typically connects only two devices directly (one transmitter to one receiver).
- USART (Universal Synchronous/Asynchronous Receiver/Transmitter): Point-to-Point Topology. It behaves like UART, with an optional added clock line, usually forming a direct 1-to-1 connection.
Detailed Breakdown
| Protocol | Primary Topology | Key Characteristic | Typical Application |
|---|---|---|---|
| SPI | Star | Dedicated Chip Select (CS/SS) for each device | High-speed, short distance (SD cards, displays) |
| I²C | Bus | Shared 2-wire bus, device addressing | Many low-speed sensors, EEPROMs |
| CAN | Linear Bus | Two-wire differential bus, multi-master | Automotive, industrial, noisy environments |
| UART | Point-to-Point | 2-wire dedicated link (TX/RX) | Debugging, MCU-to-Module communication |
| USART | Point-to-Point | Synchronous or Asynchronous, 1-to-1 | MCU-to-MCU, high-speed serial |
Topology Notes:
- SPI Daisy-Chain: SPI can also be configured in a daisy-chain topology, where data moves from one device to the next rather than directly from the master.
- CAN Stubs: While linear is the standard, small stub lines (drop lines) can be used to connect devices, but these should be kept minimal to prevent signal reflection.