SPI
About
For some APIs, the reference to be used is the same as the Arduino Core.
Example
To get started with SPI, you can try:
SPI Multiple Buses
/* The ESP32 has four SPi buses, however as of right now only two of * them are available to use, HSPI and VSPI. Simply using the SPI API * as illustrated in Arduino examples will use VSPI, leaving HSPI unused. * * However if we simply initialize two instance of the SPI class for both * of these buses both can be used. However when just using these the Arduino * way only will actually be outputting at a time. * * Logic analyzer capture is in the same folder as this example as * "multiple_bus_output.png" * * created 30/04/2018 by Alistair Symonds */ #include <SPI.h> // Define ALTERNATE_PINS to use non-standard GPIO pins for SPI bus #ifdef ALTERNATE_PINS #define VSPI_MISO 2 #define VSPI_MOSI 4 #define VSPI_SCLK 0 #define VSPI_SS 33 #define HSPI_MISO 26 #define HSPI_MOSI 27 #define HSPI_SCLK 25 #define HSPI_SS 32 #else #define VSPI_MISO MISO #define VSPI_MOSI MOSI #define VSPI_SCLK SCK #define VSPI_SS SS #define HSPI_MISO 12 #define HSPI_MOSI 13 #define HSPI_SCLK 14 #define HSPI_SS 15 #endif #if !defined(CONFIG_IDF_TARGET_ESP32) #define VSPI FSPI #endif static const int spiClk = 1000000; // 1 MHz //uninitialized pointers to SPI objects SPIClass *vspi = NULL; SPIClass *hspi = NULL; void setup() { //initialize two instances of the SPIClass attached to VSPI and HSPI respectively vspi = new SPIClass(VSPI); hspi = new SPIClass(HSPI); //clock miso mosi ss #ifndef ALTERNATE_PINS //initialize vspi with default pins //SCLK = 18, MISO = 19, MOSI = 23, SS = 5 vspi->begin(); #else //alternatively route through GPIO pins of your choice vspi->begin(VSPI_SCLK, VSPI_MISO, VSPI_MOSI, VSPI_SS); //SCLK, MISO, MOSI, SS #endif #ifndef ALTERNATE_PINS //initialize hspi with default pins //SCLK = 14, MISO = 12, MOSI = 13, SS = 15 hspi->begin(); #else //alternatively route through GPIO pins hspi->begin(HSPI_SCLK, HSPI_MISO, HSPI_MOSI, HSPI_SS); //SCLK, MISO, MOSI, SS #endif //set up slave select pins as outputs as the Arduino API //doesn't handle automatically pulling SS low pinMode(vspi->pinSS(), OUTPUT); //VSPI SS pinMode(hspi->pinSS(), OUTPUT); //HSPI SS } // the loop function runs over and over again until power down or reset void loop() { //use the SPI buses spiCommand(vspi, 0b01010101); // junk data to illustrate usage spiCommand(hspi, 0b11001100); delay(100); } void spiCommand(SPIClass *spi, byte data) { //use it as you would the regular arduino SPI API spi->beginTransaction(SPISettings(spiClk, MSBFIRST, SPI_MODE0)); digitalWrite(spi->pinSS(), LOW); //pull SS slow to prep other end for transfer spi->transfer(data); digitalWrite(spi->pinSS(), HIGH); //pull ss high to signify end of data transfer spi->endTransaction(); }