Today, at the low end of the communication protocols, we find I²C (for ‘Inter-Integrated Circuit’,
protocol) and SPI (for ‘Serial Peripheral Interface’). Both protocols are well-suited for
communications between integrated circuits, for slow communication with on-board peripherals.
At the roots of these two popular protocols we find two major companies – Philips for I²C and
Motorola for SPI – and two different histories about why, when and how the protocols were
created.