linux spi发数据

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

#define SPI_DEVICE "/dev/spidev0.0"
#define SPI_MODE 0
#define SPI_BITS_PER_WORD 8
#define SPI_SPEED 500000

int main() {
    int fd;
    uint8_t tx_buf[] = {0x01, 0x02, 0x03, 0x04};
    uint8_t rx_buf[4];
    struct spi_ioc_transfer tr = {
        .tx_buf = (unsigned long)tx_buf,
        .rx_buf = (unsigned long)rx_buf,
        .len = 4,
        .speed_hz = SPI_SPEED,
        .bits_per_word = SPI_BITS_PER_WORD,
    };

    fd = open(SPI_DEVICE, O_RDWR);
    if (fd < 0) {
        perror("Failed to open SPI device");
        return -1;
    }

    if (ioctl(fd, SPI_IOC_WR_MODE, &SPI_MODE) < 0) {
        perror("Failed to set SPI mode");
        close(fd);
        return -1;
    }

    if (ioctl(fd, SPI_IOC_MESSAGE(1), &tr) < 0) {
        perror("SPI transfer failed");
        close(fd);
        return -1;
    }

    printf("Received data: ");
    for (int i = 0; i < 4; i++) {
        printf("%02x ", rx_buf[i]);
    }
    printf("\n");

    close(fd);
    return 0;
}