SPI Implementation with source code in C++

To work with the SPI, you also need to add a specific Kernel module: Spidev. The Raspberry Pi supports this module, you need to configure it by invoking raspi-config, and then select 3 Interfacing Options and P4 SPI.

To access SPI functions with C/C++, you can use the spidev wrapper library. Following the example code, you need to configure the SPI connection, then open the device that you want to connect to, and then use the library method for reading and writing data.

//SOURCE: https://raw.githubusercontent.com/milekium/spidev-lib/master/sample/spidev-testcpp.cc
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <spidev_lib++.h>

spi_config_t spi_config;
uint8_t tx_buffer[32];
uint8_t rx_buffer[32];

int  main( void)
{

  SPI *mySPI = NULL;

  spi_config.mode=0;
  spi_config.speed=1000000;
  spi_config.delay=0;
  spi_config.bits_per_word=8;

  mySPI=new SPI("/dev/spidev1.0",&spi_config);

  if (mySPI->begin())
  {
    memset(tx_buffer,0,32);
    memset(rx_buffer,0,32);
    sprintf((char*)tx_buffer,"hello world");
    printf("sending %s, to spidev2.0 in full duplex \n ",(char*)tx_buffer);
    mySPI->xfer(tx_buffer,strlen((char*)tx_buffer),rx_buffer,strlen((char*)tx_buffer));
    printf("rx_buffer=%s\n",(char *)rx_buffer);
    //mySPI->end();
    delete mySPI;
  }
 return 1;
}