Communication buses

SPI

Serial Peripheral Interface

4-wire bus (SCK + MOSI + MISO + CS), point-to-point per device, fast (10–50 MHz).

How it looks

Real geometry: CORE3588 copper, drawn from our board file (top and bottom layers; this net in amber)

An SPI bus on CORE3588: the motion sensor talking to the computer module.

1The motion sensor U11 at this end...
2...the computer module socket J1 at the other. Five amber wires: SCK, MOSI, MISO, CS and INT.

The wires are SCK, MOSI, MISO, CS and often INT. Faster than I2C; outputs are push-pull. With four data wires it becomes QSPI.