Chapter 9: Writing SPI Device Drivers
The Serial Peripheral Interface (SPI) is (at least) a 4-wire bus – Master Input Slave Output (MISO), Master Output Slave Input (MOSI), Serial Clock (SCK), and Chip Select (CS) – which is used to connect serial flash and analog-to-digital/digital-to-analog converters. The master always generates the clock. Its speed can reach up to 80 MHz, though there is no real speed limitation (this is much faster than I2C as well). The same applies to the CS line, which is always managed by the master.
Each of these signal names has a synonym:
- Whenever you see Slave Input Master Output (SIMO), Slave Data Input (SDI), or Data Input (DI), they refer to MOSI.
- Slave Output Master Input (SOMI), Slave Data Output (SDO), and Data Output (DO) refer to MISO.
- Serial Clock (SCK), Clock (CLK), and Serial Clock (SCL) refer to SCK.
- S̅ S̅ is the Slave Select line, also called CS. CSx can be used (where x is an index such as...
