SPI for NanoPi

SPI for NanoPi

#include <stdint.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <getopt.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/types.h>
#include <linux/spi/spidev.h>

static const char *device = "/dev/spidev1.0";   // /dev/spidev0.0 or /dev/spidev0.1
static uint8_t mode = 0;                        // SPI_MODE_0 (see text)
static uint8_t bits = 8;                        // 8 or 9
static uint32_t speed = 1000000;                // Clock frequency [Hz]
static uint16_t delay = 0;                      // Time between end of data and CS de-assert

// Exit and print error code
static void exit_on_error (const char *s) {
    perror(s);
    abort();
}

int main(int argc, char *argv[]) {
    int fd;
    int Buffer_size;
    uint8_t tx[] = {0x01, 0x02, 0x04, 0x08, 0x55, 0x00, 0xAA, 0xFF, };  // Data to send
    Buffer_size = sizeof(tx);                                           // Size of TX (and RX) buffer
    uint8_t rx[sizeof(tx)] = {0, };                                     // RX buffer

    struct spi_ioc_transfer tr = {
        .tx_buf = (unsigned long)tx,
        .rx_buf = (unsigned long)rx,
        .len = Buffer_size,
        .delay_usecs = delay,
        .speed_hz = speed,
        .bits_per_word = bits,
        .cs_change = 0,
    };

    // Open SPI device
    if ((fd = open(device, O_RDWR)) < 0) exit_on_error ("Can't open SPI device");

    // Set SPI mode
    if (ioctl(fd, SPI_IOC_WR_MODE, &mode) == -1) exit_on_error ("Can't set SPI mode");

    // Read and write data (full duplex)
    if (ioctl(fd, SPI_IOC_MESSAGE(1), &tr) < 1) exit_on_error ("Can't send SPI message");

    printf ("Data from SPI Rx buffer: ");
    for (int i = 0; i < Buffer_size; i++) printf("%.2X ", rx[i]);
    printf ("\n");

    close(fd);
    return (0);
}