C语言spi代码

以下是一个基本的C语言SPI通信代码示例，以向AD5541写入数据为例：

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

#define SPI_DEVICE "/dev/spidev0.0"
#define SPI_MODE SPI_MODE_0
#define SPI_BITS_PER_WORD 8
#define SPI_SPEED_HZ 1000000

int main(int argc, char *argv[])
{
    int spi_fd, ret;
    unsigned char tx_buf[3];

    // 打开SPI设备
    spi_fd = open(SPI_DEVICE, O_RDWR);
    if (spi_fd < 0) {
        printf("Failed to open SPI device!\n");
        return -1;
    }

    // SPI模式设置
    ret = ioctl(spi_fd, SPI_IOC_WR_MODE, &SPI_MODE);
    if (ret == -1) {
        printf("Failed to set SPI mode!\n");
        return -1;
    }

    // SPI字长设置
    ret = ioctl(spi_fd, SPI_IOC_WR_BITS_PER_WORD, &SPI_BITS_PER_WORD);
    if (ret == -1) {
        printf("Failed to set SPI bits per word!\n");
        return -1;
    }

    // SPI时钟频率设置
    ret = ioctl(spi_fd, SPI_IOC_WR_MAX_SPEED_HZ, &SPI_SPEED_HZ);
    if (ret == -1) {
        printf("Failed to set SPI speed!\n");
        return -1;
    }

    // 向AD5541写入数据
    tx_buf[0] = 0x01;  // 控制字节
    tx_buf[1] = 0x12;  // 数据高8位
    tx_buf[2] = 0x34;  // 数据低8位
    ret = write(spi_fd, tx_buf, 3);
    if (ret == -1) {
        printf("Failed to write to SPI device!\n");
        return -1;
    }

    // 关闭SPI设备
    close(spi_fd);

    return 0;
}

在以上代码中，需要根据实际情况修改SPI_DEVICE、SPI_MODE、SPI_BITS_PER_WORD和SPI_SPEED_HZ这四个参数，以及向AD5541写入数据的内容。