使用Linux通过I2C读写EEPROM

概述我尝试通过I2C读取和写入带有Raspberry Pi B的 Atmel 24C256 EEPROM,但是我无法正常工作. 这是我到目前为止的代码： #include <stdio.h>#include <stdlib.h>#include <linux/i2c-dev.h>#include <fcntl.h>#include <string.h>#include <sys/ioctl. 我尝试通过I2C读取和写入带有RaspBerry Pi B的 Atmel 24C256 EEPROM,但是我无法正常工作.

这是我到目前为止的代码：

#include <stdio.h>#include <stdlib.h>#include <linux/i2c-dev.h>#include <fcntl.h>#include <string.h>#include <sys/ioctl.h>#include <sys/types.h>#include <sys/stat.h>#include <unistd.h>#include <errno.h>#include <linux/i2c.h>#define DEVICE_PATH "/dev/i2c-1"#define PAGE_SIZE 64#define DEVICE_ADDR 0x50 // 0b1010xxxxint file_desc;char buffer[PAGE_SIZE + 2]; // 64 bytes + 2 for the addressvoID teardownI2C(){    int result = close(file_desc);}voID setupI2C(){    file_desc = open(DEVICE_PATH,O_RDWR);    if(file_desc < 0)    {    printf("%s\n",strerror(errno));    exit(1);    }    if(ioctl(file_desc,I2C_SLAVE,DEVICE_ADDR) < 0)    {    printf("%s\n",strerror(errno));    teardownI2C();    exit(1);    }}int write_to_device(char addr_hi,char addr_lo,char * buf,int len){     struct i2c_rDWr_ioctl_data msg_rDWr;     struct i2c_msg i2CMSg;     char my_buf[PAGE_SIZE + 2];     if(len > PAGE_SIZE + 2)     {     printf("Can't write more than %d bytes at a time.\n",PAGE_SIZE);     return -1;     }     int i;     my_buf[0] = addr_hi;     my_buf[1] = addr_lo;     for(i= 0; i < len; i++)     {     my_buf[2+i] = buf[i];     }     msg_rDWr.msgs = &i2CMSg;     msg_rDWr.nmsgs = 1;     i2CMSg.addr  = DEVICE_ADDR;     i2CMSg.flags = 0;     i2CMSg.len   = 2+len;     i2CMSg.buf   = my_buf;    if(ioctl(file_desc,I2C_RDWR,&msg_rDWr)<0)    {    printf("write_to_device(): %s\n",strerror(errno));    return -1;    }    return 0;}int read_from_device(char addr_hi,int len){    struct i2c_rDWr_ioctl_data msg_rDWr;    struct i2c_msg             i2CMSg;    if(write_to_device(addr_hi,addr_lo,NulL,0)<0)    {    printf("read_from_device(): address reset dID not work\n");    return -1;    }    msg_rDWr.msgs = &i2CMSg;    msg_rDWr.nmsgs = 1;    i2CMSg.addr  = DEVICE_ADDR;    i2CMSg.flags = I2C_M_RD;    i2CMSg.len   = len;    i2CMSg.buf   = buf;    if(ioctl(file_desc,&msg_rDWr)<0)    {    printf("read_from_device(): %s\n",strerror(errno));    return -1;    }    return 0;}voID fill_buffer(char *buf){    int i = 0;    while(i < PAGE_SIZE && *buf)    {    buffer[i+2] = *buf++;    }    while(i++ < PAGE_SIZE-1)    {    buffer[i+2] = '*'; // fill the buffer with something    }}int main(){    setupI2C(); //setup    fill_buffer("Here are some words.");    write_to_device(0x01,0x00,buffer,PAGE_SIZE);    char newbuf[PAGE_SIZE];    if(read_from_device(0x01,newbuf,PAGE_SIZE)>0)    {    printf("%s\n",newbuf);    }    teardownI2C(); //cleanup    return EXIT_SUCCESS;}

写入设备,如行write_to_device(0x01,PAGE_SIZE);不会产生任何错误但是当我尝试从设备读取时,我必须根据规格表写一个“虚拟”字节,然后尝试从设备读取但由于某种原因写入虚拟字节会导致错误“输入/输出错误”.我无法弄清楚它是如何工作的.我正在使用两个资源来指导我,Linux I2C-Dev documentation和similar EEPROM device.的一个例子我有点卡在这里,不知道该尝试什么.任何建议或指针都非常感谢！

解决方法 或者,如果您能够为RaspBerry Pi编译和安装不同的内核设备树,则可以通过内核at24.c驱动程序访问它.

内核设备树需要指定EEPROM的类型和地址,以及它连接的I²C总线.我不确定RaspBerry Pi,但对于BeagleBone Black EEPROM,它是这样的：

&i2c0 {    eeprom: eeprom@50 {        compatible = "at,24c32";        reg = <0x50>;    };};

对于您的设备,您需要指定compatible =“at,24c256”;

确保内核配置指定CONfig_EEPROM_AT24 = y(或= m).

然后,您应该能够从/ sys / bus / i2c / devices / 0-0050 / eeprom或/ sys / bus / i2c / drivers / at24 / 0-0050 / eeprom等用户空间访问EEPROM存储器.

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