imx6ul i2c调试（代码）

叁歲伎倆 2022-12-30 03:57 167阅读 0赞

i2c这里的调试要注意的是管脚的功能配置，需要更改设备树文件；

更改设备树文件：[https://blog.csdn.net/cao849861802/article/details/111604277][https_blog.csdn.net_cao849861802_article_details_111604277]

设备树文件修改好了，才能在/dev下看到i2c设备比如i2c-0，i2c-1；

我这边读写设备是个e2prom，然后注意地址和传入长度，代码中的设备地址是从第七位开始的，因为读写位已经整合到了其他地方，所以地址有效的只有七位，第一位设置一定为0

#include <errno.h>
    #include <stdio.h>
    #include <stdlib.h>
    #include <fcntl.h>
    #include <unistd.h>
    #include <sys/ioctl.h>
    #include <linux/i2c.h>
    #include <linux/i2c-dev.h>
    #include <string.h>
    
    #define I2C_WRITE_DATA  0
    #define I2C_READ_DATA   1
    
    
    
    struct i2cMsg
    {
    	unsigned short addr;
    	unsigned short flags;
    	unsigned short len;
    	unsigned char *buf;
    }; 
    
    struct i2c_ioctl_data
    {
    	struct i2cMsg *msgs;
    	int nmsgs;
    };
    
    
    int i2cfd[2];
    
    
    void i2cWrite(int fd,unsigned short devaddr,unsigned char *buf,unsigned short buflen)
    {
    	struct i2cMsg msg[2];
    	struct i2c_ioctl_data date;
    	int ret = 0;
    	
    	if(buf == NULL)
    		return ;
    	
    	msg[0].len = buflen;//buf len
    	msg[0].flags = I2C_WRITE_DATA;//0write  1read
    	msg[0].addr = devaddr;//dev addr
    	msg[0].buf = buf;
    	
    	date.nmsgs = 1;
    	date.msgs = (struct i2cMsg *)&msg;
    	
    	ret = ioctl(fd,I2C_RDWR,(unsigned long)&date);
    	if(ret < 0)
    	{
    		printf("i2c write date ioctrl set failed,ret = %d\r\n",ret);
    	}
    }
    
    
    
    void i2cRead(int fd,unsigned short devaddr,unsigned char *buf,unsigned short buflen,unsigned char *retbuf,unsigned short retbuflen)
    {
    	struct i2cMsg msg[2];
    	struct i2c_ioctl_data date;
    	int ret = 0;
    	
    	if(buf == NULL)
    		return ;
    	
    	msg[0].len = buflen;//buf len
    	msg[0].flags = I2C_WRITE_DATA;//0write  1read
    	msg[0].addr = devaddr;//dev addr
    	msg[0].buf = buf;
    
    	msg[1].len = retbuflen;//buf len
    	msg[1].flags = I2C_READ_DATA;//0write  1read
    	msg[1].addr = devaddr;//dev addr
    	msg[1].buf = retbuf;
    
    	date.nmsgs = 2;
    	date.msgs = (struct i2cMsg *)&msg;
    	
    	ret = ioctl(fd,I2C_RDWR,(unsigned long)&date);
    	if(ret < 0)
    	{
    		printf("i2c read date ioctrl set failed,ret = %d\r\n",ret);
    	}
    }
    
    
    void main()
    {
    	int i = 0;
    	int ret = 0;
    	unsigned char buf[64];
    	unsigned char retbuf[64];
    	unsigned short devaddr = 0x50;
    
    	
    	for(i = 0; i < 2; i++)
    	{
    		printf("i2c %d task start------\r\n",i);
    		memset(buf,0,sizeof(buf));
    		sprintf(buf,"/dev/i2c-%d",i);
    		i2cfd[i] = open(buf, O_RDWR);
    		if(i2cfd[i] < 0)
    		{
    			printf("i2c-%d fd open failed\r\n",i);
    			i2cfd[i] = -1;
    			return;
    		}
    
    		ioctl(i2cfd[i],I2C_TIMEOUT,1);/*超时时间*/
    		ioctl(i2cfd[i],I2C_RETRIES,2);/*重复次数*/
    		
    		memset(buf,0,sizeof(buf));
    		buf[0] = 0x00;//reg addr 0;
    		buf[1] = 0x01;//reg addr 1
    		buf[2] = 0x11;//data
    		i2cWrite(i2cfd[i],devaddr,buf,3);
    		
    		sleep(1);
    		
    		memset(buf,0,sizeof(buf));
    		memset(retbuf,0,sizeof(retbuf));
    		buf[0] = 0x00;//reg addr;
    		buf[1] = 0x01;//reg addr;
    		i2cRead(i2cfd[i],devaddr,buf,2,retbuf,1);
    		
    		printf("i2c %d buf = %x",i,retbuf[0]);
    		
    		close(i2cfd[i]);
    		close(i2cfd[i]);	
    		printf("i2c %d close\r\n",i);
    	}
    	
    
    }

[https_blog.csdn.net_cao849861802_article_details_111604277]: https://blog.csdn.net/cao849861802/article/details/111604277