ESP32 integrates four SPI peripherals.
- SPI0 and SPI1 are used internally to access the ESP32’s attached flash memory and thus are currently not open to users. They share one signal bus via an arbiter.
- SPI2 and SPI3 are general purpose SPI controllers, sometimes referred to as HSPI and VSPI, respectively. They are open to users. SPI2 and SPI3 have independent signal buses with the same respective names. Each bus has three CS lines to drive up to three SPI slaves.