嵌入式linux应用读写spi简单示例

1、打开spi设备文件
2、配置模数、速度、位数等
3、读写操作
4、关闭

spi.c

#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 int fd = 0;

int spi_init(char *spi_dev,int mode,int nits,int speed)
{
    
    
	fd = open(spi_dev, O_RDWR);
	if (fd < 0)
	{
    
    
		printf("[%s]:[%d] open spi file error\r\n", __FUNCTION__, __LINE__);
		return -1;
	}
	//设置模式
	ret = ioctl(fd, SPI_IOC_WR_MODE, &mode);
	if (ret == -1)
		pabort("can't set spi mode");

	ret = ioctl(fd, SPI_IOC_RD_MODE, &mode);
	if (ret == -1)
		pabort("can't get spi mode");

	//设置一次多少位
	ret = ioctl(fd, SPI_IOC_WR_BITS_PER_WORD, &bits);
	if (ret == -1)
		pabort("can't set bits per word");

	ret = ioctl(fd, SPI_IOC_RD_BITS_PER_WORD, &bits);
	if (ret == -1)
		pabort("can't get bits per word");

	//设置最大速度
	ret = ioctl(fd, SPI_IOC_WR_MAX_SPEED_HZ, &speed);
	if (ret == -1)
		pabort("can't set max speed hz");

	ret = ioctl(fd, SPI_IOC_RD_MAX_SPEED_HZ, &speed);
	if (ret == -1)
		pabort("can't get max speed hz");

	printf("spi mode: %d\n", mode);
	printf("bits per word: %d\n", bits);
	printf("max speed: %d Hz (%d KHz)\n", speed, speed/1000);
	return 0;
}

int spi_readwrte(unsigned char *txbuf, unsigned char *rxbuf, int len)
{
    
    
	struct spi_ioc_transfer tr =
	 {
    
    
		.tx_buf = (unsigned long *)txbuf,        //发送缓存区
		.rx_buf = (unsigned long *)rxbuf,        //接收缓存区
		.len = len/4,
		.delay_usecs = delay,               //发送时间间隔
		.speed_hz = speed,                  //总线速率
		.bits_per_word = bits,              //收发的一个字的二进制位数
	};

	ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);
	if (ret < 1)
		pabort("can't send spi message");

	for (ret = 0; ret < len/4; ret++) 
	{
    
    
		if (!(ret % 6))
			puts("");
		printf("%.2X ", rx[ret]);
	}
	
	return 0;
}

int spi_close()
{
    
    
	close(fd);
	return 0;
}

main.c

int main()
{
    
    
	unsigned char txbuf[] = "hello",rxbuf[50] = {
    
    0};
	spi_init("/dev/spi1.0",SPI_CPHA|SPI_CPOL,int nits,short long speed);
	spi_readwrte(txbuf,  rxbuf,5);
	printf("spi rcv %x%x%x%x%x\n",rxbuf[0],rxbuf[1],rxbuf[2],rxbuf[3],rxbuf[4]);
	spi_close();
	return 0;
}