| Unlike I2C, SPI does not use bi-directional signals and therefore does not need tri-state buffers to control which device has access to the bus at any time. I2C is also a multi-master protocol, where any number of devices connected to the bus can initiate a data transfer, whereas SPI has only one master. I2C scales better when large numbers of components are used on the same bus, since SPI requires one chip-select signal for each component. Instead, I2C uses 7-bit addresses to identify which component on the bus is being communicated with. |