A different approach is SPI. Introduced in the late 1980s, this technology aimed to replace asynchronous serial communication towards peripherals, by introducing a number of improvements:
- Serial clock line to synchronize the endpoints
- Master-slave protocol
- One-to-many communication over the same three-wire bus
The master device, usually the microcontroller, shares the bus with one or more slaves. To trigger the communication, a separate slave select (SS) signal is used to address each slave connected to the bus. The bus uses two independent signals for data transfer, one per direction, and a shared clock line that synchronizes the two ends of the communication. Due to the clock line being generated by the master, the data transfer is ...
