How to use SPI with ESP32 and Arduino - arduino

Question

I'm trying to send out data from SPI, but can't get it to work. There appear no data on the SPI ports (D12, 13, 14; checked with an oscilloscope) and the ESP32 seems to hang. I would like to use the HSPI port.
I am also wondering whether I need a special driver for SPI to work on ESP32 and if so, how can I check if I already have that and how do I install it. When I look in the library manager, I see no special SPI driver.
I have tried using this program (copied from https://diyi0t.com/spi-tutorial-for-arduino-and-esp8266/). It's apparently intended for esp8266. Should it work out of the box also for ESP32?
#include "SPI.h"
char buff[]="Hello Slave\n";
void setup() {
SPI.begin();
}
void loop() {
for(int i=0; i<sizeof buff; i++)
{
SPI.transfer(buff[i]);
}
delay(1000);
}
and also with this program:
#include "SPI.h"
char buff[]="Hello Slave\n";
SPIClass SPI1(HSPI);
void setup() {
SPI1.begin();
SPI1.setClockDivider(80);
}
void loop() {
for(int i=0; i<sizeof buff; i++)
{
SPI1.transfer(buff[i]);
}
delay(1000);
}
I am using a 30 pin ESP32 dev board, Arduino version 1.8.13. In preferences-->more board managers, it says:
http://arduino.esp8266.com/stable/package_esp8266com_index.json, https://dl.espressif.com/dl/package_esp32_index.json

Answer 1

For ESP32, you need to declare which SPI instance you want to use, like so:
#include <SPI.h>
SPIClass SPI1(HSPI);
SPI1.begin();
// Optional
// SPI1.beginTransaction(SPISettings(3000000, MSBFIRST, SPI_MODE2));
The rest is the same as ESP8266

Answer 2

#include <SPI.h>
#define HSPI_MISO 12
#define HSPI_MOSI 13
#define HSPI_SCLK 14
#define HSPI_CS 15
static const int spiClk = 240000000; // 1 MHz
SPIClass * hspi = NULL;
char buff[]="Hello Slave\n";
//byte buff[] = {0xAA, 0xBB, 0xAA, 0x01,
0x89, 0xAB, 0xCD, 0xEF};
void setup() {
Serial.begin(9600);
hspi = new SPIClass(HSPI);
hspi->begin();
hspi->begin(HSPI_SCLK, HSPI_MISO, HSPI_MOSI, HSPI_CS); //SCLK, MISO, MOSI, SS
pinMode(HSPI_CS, OUTPUT); //HSPI SS
}
void loop() {
for(int i=0; i<sizeof buff; i++)
{
SPI.transfer(buff[i]);
Serial.println(buff[i]);
}
delay(1000);
}

Answer 3

Assuming that you use the ESP32 Arduino Core, under the docs it is written that SPI is has a suppported Arduino API implementation. Thus using the Arduino SPI API, it should work, like all other devices (the ESP32 Arduino Core implementation conforms to the API defined by Arduino, of course I would check if your board's pinout corresponds to the Espressif defined ESP32 pinout).
If you want to see some examples, you can find one here. All supported APIs have examples on the ESP32 Arduino Core repo on GitHub.
I also want to point out that in the Arduino IDE (or the VSCode plugin) you can find examples for SPI, I would take a look as well for that.