I.MX6 I2C DS1337 disable square-wave output

                   linux I2C DS1337 disable square-wave output

                        \\\\\\\\\\\-*- 目录 -*-//////////
                        |   一、DS1337访问寄存器说明：
                        |   二、cat main.c
                        |   三、cat i2c_data.c
                        |   四、cat i2c_data.h
                        |   五、cat Android.mk
                        --------------------------------

一、DS1337控制寄存器说明：
    . reference:
       . DS1337 I2C Serial Real-Time Clock
       . How to: wire the DS1337 RTC?
           http://forum.arduino.cc/index.php?topic=20937.0. SPECIAL-PURPOSE REGISTERS
       The DS1337 has two additional registers (control and status) that control the RTC, alarms, and square-wave output.
    . Control Register (0Eh)
       +-------+-------+-------+-------+-------+-------+-------+-------+
       | Bit  | Bit  | Bit  | Bit  | Bit  | Bit  | Bit  | Bit  |
       +-------+-------+-------+-------+-------+-------+-------+-------+
       | EOSC  |      |      | RS2   | RS1   | INTCN | A2IE  | A1IE  |
       +-------+-------+-------+-------+-------+-------+-------+-------+
       . Bit : Enable Oscillator (EOSC). This active-low bit when set to logic  starts the oscillator. When this bit is set to logic , the oscillator is stopped. This bit is enabled (logic ) when power is first applied.
       . Bits  and : Rate Select (RS2 and RS1). These bits control the frequency of the square-wave output when the square wave has been enabled. The table below shows the square-wave frequencies that can be selected with the RS bits. These bits are both set to logic  (32kHz) when power is first applied.
       . SQW/INTB Output:
           +------+-----+-----+-----------+------+
           | NTCN | RS2 | RS1 | SQW/INTB  | A2IE |
           |      |     |     |  OUTPUT   |      |
           +------+-----+-----+-----------+------+
           |     |    |    | 1Hz       | X    |
           +------+-----+-----+-----------+------+
           |     |    |    | .096kHz  | X    |
           +------+-----+-----+-----------+------+
           |     |    |    | .192kHz  | X    |
           +------+-----+-----+-----------+------+
           |     |    |    | .768kHz | X    |
           +------+-----+-----+-----------+------+
           |     | X   | X   | A2F       |     |
           +------+-----+-----+-----------+------+
       . Bit : Interrupt Control (INTCN). This bit controls the relationship between the two alarms and the interrupt output  pins. When the INTCN bit is set to logic , a match between the timekeeping registers and the alarm  registers l activates the INTA pin (provided that the alarm is enabled) and a match between the timekeeping registers and the alarm  registers activates the SQW/INTB pin (provided that the alarm is enabled). When the INTCN bit is set to logic , a square wave is output on the SQW/INTB pin. This bit is set to logic  when power is first applied.
       . Bit : Alarm  Interrupt Enable (A2IE). When set to logic , this bit permits the alarm  flag (A2F) bit in the status register to assert INTA (when INTCN = ) or to assert SQW/INTB (when INTCN = ). When the A2IE bit is set to logic , the A2F bit does not initiate an interrupt signal. The A2IE bit is disabled (logic ) when power is first applied.
       . Bit : Alarm  Interrupt Enable (A1IE). When set to logic , this bit permits the alarm  flag (A1F) bit in the status register to assert INTA. When the A1IE bit is set to logic , the A1F bit does not initiate the INTA signal. The A1IE bit is disabled (logic ) when power is first applied. 

二、cat main.c
    #include <stdio.h>
    #include <fcntl.h>
    #include <unistd.h>
    #include "i2c-dev.h"
    #include "i2c.h"
    #include "i2c_data.h"

    int main ( int argc, char ** argv ) {
        int fd,ret;

        fd = open( "/dev/i2c-2", O_RDWR );
        if ( fd <  ) {
            perror( "open error\n" );
        }

        unsigned char ch = ;
        // 通过测试秒数来判断访问芯片DS1337没问题
        // terminal output: get data from ds1337 0x00: 54
        i2c_data_read_byte( fd, 0x68, 0x00, &ch );
        printf( "get data from ds1337 0x00: %x\n", ch );

        i2c_data_read_byte( fd, 0x68, 0x0e, &ch );
        // terminal output: get data from ds1337 0x0e: 18
        printf( "get data from ds1337 0x0e: %x\n", ch );

        // 关闭方波输出
        ch = 0x98;
        i2c_data_write_byte( fd, 0x68, 0x0e, ch );

        i2c_data_read_byte( fd, 0x68, 0x0e, &ch );
        // terminal output: get data from ds1337 0x0e: 98
        printf( "get data from ds1337 0x0e: %x\n", ch );

        i2c_data_read_byte( fd, 0x68, 0x0F, &ch );
        // terminal output: get data from ds1337 0x0f: 0
        printf( "get data from ds1337 0x0f: %x\n", ch );

        close( fd );

        return ;
    }

三、cat i2c_data.c
    #include <stdio.h>
    #include <string.h>
    #include <linux/types.h>
    #include <stdlib.h>
    #include <fcntl.h>
    #include <unistd.h>
    #include <sys/types.h>
    #include <sys/ioctl.h>
    #include <errno.h>
    #include "i2c-dev.h"
    #include "i2c.h"
    #include "i2c_data.h"

    // A demo for test
    int eepromDemo ( int argc, char **argv ) {
        int fd,ret;

        fd = open("/dev/i2c-3",O_RDWR);
        if ( fd <  ) {
            perror("open error\n");
        }

        unsigned char buf[] = {'x', 'x', 'x', '', 'y', 'm', '\0'};
        i2c_data_write_byte( fd, 0x50, , 'z' );
        i2c_data_write_byte( fd, 0x50, , 'j' );
        i2c_data_write_byte( fd, 0x50, , 'f' );
        //printf("i2c function test: %s\n", buf);
        //i2c_data_write_byte (fd, 0x50, 3, buf[1]);
        //i2c_data_read_str (fd, 0x50, 0, buf, array_size(buf)-1);

        //unsigned char ch = 0;
        i2c_data_read_byte(fd, 0x50, , &ch);

        close(fd);

        return ;
    }

    /*****************************************************************************
     * 函数说明：
     *     往i2c设备写数据，写一串字节
     * 参数说明：
     *     1. fd：     文件描述符
     *     2. addr：   i2c设备地址
     *     3. offset： i2c设备内寄存器偏移地址
     *     4. buf：    字节数组
     *     5. count：  字节数组长度
     * 返回值：
     *     正常返回写入的个数，如果出错，返回错误码
     ****************************************************************************/
    int i2c_data_write_str (int fd, int addr, int offset, unsigned char *buf, int count) {
        int ret = ;
        struct i2c_rdwr_ioctl_data i2c_data;

        i2c_data.nmsgs = ;     /* 每次只写一个字节 */
        i2c_data.msgs  = (struct i2c_msg*)malloc(i2c_data.nmsgs*sizeof(struct i2c_msg));
        if(!i2c_data.msgs)
        {
            perror("i2c_data_write_str function malloc error.\n");
            return -;
        }

        ioctl(fd, I2C_TIMEOUT, ); /*超时时间*/
        ioctl(fd, I2C_RETRIES, ); /*重复次数*/

        (i2c_data.msgs[]).buf = (unsigned char*)malloc();

        int i = ;
        for (i = ; i < count; i++) {

            (i2c_data.msgs[]).len      = ;
            (i2c_data.msgs[]).addr     = addr;     //i2c 设备地址
            (i2c_data.msgs[]).flags    = ;        //write
            (i2c_data.msgs[]).buf[]   = (unsigned char)offset+i;   // i2c 写入目标的地址
            (i2c_data.msgs[]).buf[]   = (unsigned char)buf[i];     //the data to write

            ret = ioctl(fd, I2C_RDWR, (unsigned long)&i2c_data);
            if(ret < ) {
                perror("i2c_data_write_str ioctl error");
                return ret;
            }
        }   

        free((i2c_data.msgs[]).buf);
        free(i2c_data.msgs);
        return i;
    }

    /************************************************************************
     * 函数说明：
     *     往i2c设备写数据，写一个字节
     * 参数说明：
     *     1. fd：     文件描述符
     *     2. addr：   i2c设备地址
     *     3. offset： i2c设备内寄存器偏移地址
     *     4. buf：    要写入的字节
     * 返回值：
     *     正常返回0，出错，返回错误码；
     ************************************************************************/
    int i2c_data_write_byte (int fd, int addr, int offset, unsigned char buf) {

        int ret = ;
        struct i2c_rdwr_ioctl_data i2c_data;

        i2c_data.nmsgs = ; /* 每次只写一个字节 */
        i2c_data.msgs  = (struct i2c_msg*)malloc(i2c_data.nmsgs*sizeof(struct i2c_msg));
        if(!i2c_data.msgs)
        {
            perror("i2c_data_write_byte function malloc error.\n");
            return -;
        }

        ioctl(fd,I2C_TIMEOUT,); /*超时时间*/
        ioctl(fd,I2C_RETRIES,); /*重复次数*/

        (i2c_data.msgs[]).buf      = (unsigned char*)malloc();

        (i2c_data.msgs[]).len      = ;
        (i2c_data.msgs[]).addr     = addr;     //i2c 设备地址
        (i2c_data.msgs[]).flags    = ;        //write
        (i2c_data.msgs[]).buf[]   = (unsigned char)offset;    // i2c 写入目标的地址
        (i2c_data.msgs[]).buf[]   = (unsigned char)buf;       //the data to write

        ret = ioctl(fd, 0x0707, (unsigned long)&i2c_data);
        if(ret < ) {
            perror("i2c_data_write_byte ioctl error");
            return ret;
        }   

        free((i2c_data.msgs[]).buf);
        free(i2c_data.msgs);
        return ret;
    }

    /*************************************************************************
     * 函数说明：
     *     从i2c设备读数据，读一个字节
     * 参数说明：
     *     1. fd：     文件描述符
     *     2. addr：   i2c设备地址
     *     3. offset： i2c设备内寄存器偏移地址
     *     4. buf：    保存读出的字节指针
     * 返回值：
     *     正常返回0，出错，返回错误码；
     ************************************************************************/
    int i2c_data_read_byte (int fd, int addr, int offset, unsigned char *buf) {
        int ret;
        struct i2c_rdwr_ioctl_data i2c_data;

        i2c_data.nmsgs = ; /*读时序为2个开始信号*/
        i2c_data.msgs  = (struct i2c_msg*)malloc(i2c_data.nmsgs*sizeof(struct i2c_msg));
        if(!i2c_data.msgs) {
            perror("i2c_data_read_byte functionmalloc error");
            exit();
        }

        ioctl(fd,I2C_TIMEOUT,); /*超时时间*/
        ioctl(fd,I2C_RETRIES,); /*重复次数*/

        (i2c_data.msgs[]).len      = ;        //i2c 目标数据的地址
        (i2c_data.msgs[]).addr     = addr;     // i2c 设备地址
        (i2c_data.msgs[]).flags    = ;        //write
        (i2c_data.msgs[]).buf      = (unsigned char*)malloc();
        (i2c_data.msgs[]).buf[]   = offset;   //i2c 数据地址

        (i2c_data.msgs[]).len      = ;        //读出的数据
        (i2c_data.msgs[]).addr     = addr;     // i2c 设备地址
        (i2c_data.msgs[]).flags    = I2C_M_RD; //read
        (i2c_data.msgs[]).buf      = (unsigned char*)malloc();//存放返回值的地址。
        (i2c_data.msgs[]).buf[]   = ;        //初始化读缓冲

        ret = ioctl(fd, I2C_RDWR, (unsigned long)&i2c_data);
        if(ret<) {
            perror("i2c_data_read_byte ioctl error.\n");
            return ret;
        }

        //printf("buff[0] = %x\n",i2c_data.msgs[1].buf[0]);
        *buf = i2c_data.msgs[].buf[];

        free((i2c_data.msgs[]).buf);
        free((i2c_data.msgs[]).buf);
        free(i2c_data.msgs);

        return ret;
    }

    /**********************************************************************************
     * 函数说明：
     *     从i2c设备读数据，读一串字节
     * 参数说明：
     *     1. fd：     文件描述符
     *     2. addr：   i2c设备地址
     *     3. offset： i2c设备内寄存器偏移地址
     *     4. buf：    保存从i2c设备读出数据的字节数组指针
     *     5. count：  要读的字节个数
     * 返回值：
     *     正常返回0，如果出错，返回错误码
     **********************************************************************************/
    int i2c_data_read_str (int fd, int addr, int offset, unsigned char *buf, int count) {
        int ret;
        struct i2c_rdwr_ioctl_data i2c_data;

        i2c_data.nmsgs = ;
        i2c_data.msgs  = (struct i2c_msg*)malloc(i2c_data.nmsgs*sizeof(struct i2c_msg));
        if(!i2c_data.msgs) {
            perror("i2c_data_read_byte functionmalloc error");
            exit();
        }

        ioctl(fd, I2C_TIMEOUT, ); /*超时时间*/
        ioctl(fd, I2C_RETRIES, ); /*重复次数*/

        (i2c_data.msgs[]).len      = ;        //i2c 目标数据的地址
        (i2c_data.msgs[]).addr     = addr;     // i2c 设备地址
        (i2c_data.msgs[]).flags    = ;        //write
        (i2c_data.msgs[]).buf      = (unsigned char*)malloc();
        (i2c_data.msgs[]).buf[]   = offset;   //i2c 数据地址

        (i2c_data.msgs[]).len      = count;    //读出的数据
        (i2c_data.msgs[]).addr     = addr;     // i2c 设备地址
        (i2c_data.msgs[]).flags    = I2C_M_RD; //read
        (i2c_data.msgs[]).buf      = buf;      //存放返回值的地址。

        ret = ioctl(fd, I2C_RDWR, (unsigned long)&i2c_data);
        if(ret<) {
            perror("i2c_data_read_byte ioctl error.\n");
            return ret;
        }
        //buf[count] = 0;
        //printf("buf = %s\n", buf);

        free((i2c_data.msgs[]).buf);
        free(i2c_data.msgs);

        return ;
    }

四、cat i2c_data.h
    /**************************************************************************************
     * 声明：
     *     这个函数库主要用于读写i2c设备，提供了以下功能：
     *         1. 读一串字节：i2c_data_read_str()
     *         2. 读一个字节：i2c_data_read_byte()
     *         3. 写一串字节：i2c_data_write_str()
     *         4. 写一个字节：i2c_data_write_byte()
     *
     *
     *                                      write by zengjf     2015-4-28
     **************************************************************************************/
    #ifndef __I2C_DATA_H__
        #define __I2C_DATA_H__

    #define array_size(array_buffer) (sizeof(array_buffer)/sizeof(*array_buffer))

    /**********************************************************************************
     * 函数说明：
     *     往i2c设备写数据，写一串字节
     * 参数说明：
     *     1. fd：     文件描述符
     *     2. addr：   i2c设备地址
     *     3. offset： i2c设备内寄存器偏移地址
     *     4. buf：    字节数组
     *     5. count：  字节数组长度
     * 返回值：
     *     正常返回写入的个数，如果出错，返回错误码
     *********************************************************************************/
    int i2c_data_write_str (int fd, int addr, int offset, unsigned char *buf, int count);

    /**********************************************************************************
     * 函数说明：
     *     从i2c设备读数据，读一串字节
     * 参数说明：
     *     1. fd：     文件描述符
     *     2. addr：   i2c设备地址
     *     3. offset： i2c设备内寄存器偏移地址
     *     4. buf：    保存从i2c设备读出数据的字节数组指针
     *     5. count：  要读的字节个数
     * 返回值：
     *     正常返回0，如果出错，返回错误码
     **********************************************************************************/
    int i2c_data_read_str (int fd, int addr, int offset, unsigned char *buf, int count);

    /**********************************************************************************
     * 函数说明：
     *     往i2c设备写数据，写一个字节
     * 参数说明：
     *     1. fd：     文件描述符
     *     2. addr：   i2c设备地址
     *     3. offset： i2c设备内寄存器偏移地址
     *     4. buf：    要写入的字节
     * 返回值：
     *     正常返回0，出错，返回错误码；
     **********************************************************************************/
    int i2c_data_write_byte (int fd, int addr, int offset, unsigned char buf);

    /**********************************************************************************
     * 函数说明：
     *     从i2c设备读数据，读一个字节
     * 参数说明：
     *     1. fd：     文件描述符
     *     2. addr：   i2c设备地址
     *     3. offset： i2c设备内寄存器偏移地址
     *     4. buf：    保存读出的字节指针
     * 返回值：
     *     正常返回0，出错，返回错误码；
     **********************************************************************************/
    int i2c_data_read_byte (int fd, int addr, int offset, unsigned char *buf);

    #endif //__I2C_DATA_H__

五、cat Android.mk
    LOCAL_PATH := $(call my-dir)

    include $(CLEAR_VARS)

    LOCAL_MODULE    := linuxTest
    LOCAL_SRC_FILES := linuxTest.c i2c_data.c

    include $(BUILD_EXECUTABLE)