zoukankan      html  css  js  c++  java
  • Linux i2c 读写程序

    /*
    This software uses a BSD license.

    Copyright (c) 2010, Sean Cross / chumby industries
    All rights reserved.
    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions
    are met:

    * Redistributions of source code must retain the above copyright
       notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright
       notice, this list of conditions and the following disclaimer in the
       documentation and/or other materials provided with the
       distribution. 
    * Neither the name of Sean Cross / chumby industries nor the names
       of its contributors may be used to endorse or promote products
       derived from this software without specific prior written
       permission.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
    A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
    HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
    OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
    AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
    WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
    POSSIBILITY OF SUCH DAMAGE.
    */

    #include <stdio.h>
    #include <linux/i2c.h>
    #include <linux/i2c-dev.h>
    #include <fcntl.h>
    #include <stdlib.h>
    #include <unistd.h>
    #include <sys/ioctl.h>
    #include <string.h>

    #define I2C_FILE_NAME "/dev/i2c-1"
    #define USAGE_MESSAGE
        "Usage: "
        "  %s r [addr] [register]   "
            "to read value from [register] "
        "  %s w [addr] [register] [value]   "
            "to write a value [value] to register [register] "
        ""

    static int set_i2c_register(int file,
                                unsigned char addr,
                                unsigned char reg,
                                unsigned char value) {

        unsigned char outbuf[2];
        struct i2c_rdwr_ioctl_data packets;
        struct i2c_msg messages[1];

        messages[0].addr  = addr;
        messages[0].flags = 0;
        messages[0].len   = sizeof(outbuf);
        messages[0].buf   = outbuf;

        /* The first byte indicates which register we'll write */
        outbuf[0] = reg;

        /*
         * The second byte indicates the value to write.  Note that for many
         * devices, we can write multiple, sequential registers at once by
         * simply making outbuf bigger.
         */
        outbuf[1] = value;

        /* Transfer the i2c packets to the kernel and verify it worked */
        packets.msgs  = messages;
        packets.nmsgs = 1;
        if(ioctl(file, I2C_RDWR, &packets) < 0) {
            perror("Unable to send data");
            return 1;
        }

        return 0;
    }

    static int get_i2c_register(int file,
                                unsigned char addr,
                                unsigned char reg,
                                unsigned char *val) {
        unsigned char inbuf, outbuf;
        struct i2c_rdwr_ioctl_data packets;
        struct i2c_msg messages[2];

        /*
         * In order to read a register, we first do a "dummy write" by writing
         * 0 bytes to the register we want to read from.  This is similar to
         * the packet in set_i2c_register, except it's 1 byte rather than 2.
         */
        outbuf = reg;
        messages[0].addr  = addr;
        messages[0].flags = 0;
        messages[0].len   = sizeof(outbuf);
        messages[0].buf   = &outbuf;

        /* The data will get returned in this structure */
        messages[1].addr  = addr;
        messages[1].flags = I2C_M_RD/* | I2C_M_NOSTART*/;
        messages[1].len   = sizeof(inbuf);
        messages[1].buf   = &inbuf;

        /* Send the request to the kernel and get the result back */
        packets.msgs      = messages;
        packets.nmsgs     = 2;
        if(ioctl(file, I2C_RDWR, &packets) < 0) {
            perror("Unable to send data");
            return 1;
        }
        *val = inbuf;

        return 0;
    }

    int main(int argc, char **argv) {
        int i2c_file;

        // Open a connection to the I2C userspace control file.
        if ((i2c_file = open(I2C_FILE_NAME, O_RDWR)) < 0) {
            perror("Unable to open i2c control file");
            exit(1);
        }

        if(argc > 3 && !strcmp(argv[1], "r")) {
            int addr = strtol(argv[2], NULL, 0);
            int reg = strtol(argv[3], NULL, 0);
            unsigned char value;
            if(get_i2c_register(i2c_file, addr, reg, &value)) {
                printf("Unable to get register! ");
            }
            else {
                printf("Register %d: %d (%x) ", reg, (int)value, (int)value);
            }
        }
        else if(argc > 4 && !strcmp(argv[1], "w")) {
            int addr = strtol(argv[2], NULL, 0);
            int reg = strtol(argv[3], NULL, 0);
            int value = strtol(argv[4], NULL, 0);
            if(set_i2c_register(i2c_file, addr, reg, value)) {
                printf("Unable to get register! ");
            }
            else {
                printf("Set register %x: %d (%x) ", reg, value, value);
            }
        }
        else {
            fprintf(stderr, USAGE_MESSAGE, argv[0], argv[0]);
        }

        close(i2c_file);

        return 0;
    }

    参考链接:http://blog.csdn.net/zfzf294990051/article/details/17322621

  • 相关阅读:
    配置secondarynamenode主机名masters
    配置secondarynamenode主机名masters
    Redis 数据备份与恢复
    Redis 数据备份与恢复
    以太坊:Go、Java、Python、Ruby、JS客户端介绍
    以太坊:创建安全多签名钱包及高级设置
    以太坊:导入预售钱包,更新、备份、恢复账号
    以太坊客户端的选择与安装
    以太坊:C++客户端的安装与定制(一)
    2019最受欢迎数据库:MySQL居首PostgreSQL第二Oracle位列第八
  • 原文地址:https://www.cnblogs.com/klcf0220/p/4337143.html
Copyright © 2011-2022 走看看