Examples

前段时间做项目，需要gpio模拟i2c通信，最后参考了一些资料，然后编写了一个程序。现在发出来，以免以后忘记，也为一些需要的朋友提供参考。不喜勿喷哈。

/* 说明：该程序是基于atmel公司的sama5d35 MCU 用其中两个GPIO引脚模拟i2c通信。
* 其中两个引脚连接到了hd1650上面。然后检测按键扫描的驱动
* */

该程序可以作为gpio模拟i2c程序的参考。不同的平台，函数实现不同，但是i2c通信的时序和原理是相同的。希望对一些朋友有帮助。

#include<linux/init.h>
#include<linux/module.h>
#include<linux/kernel.h>
#include<linux/sched.h>
#include<linux/init.h>
#include<linux/sched.h>
#include<linux/completion.h>
#include <asm/system.h>
#include <linux/param.h>
#include<linux/gpio.h>
#include<linux/cdev.h>
#include<linux/fs.h>
#include<linux/device.h>
#include<linux/slab.h>
#include<asm/uaccess.h>
#include<linux/delay.h>
#include<linux/miscdevice.h>




/* 定义GPIO引脚值，这个在内核里面有定义 */
#define GPIO_PC30 94
#define GPIO_PC31 95


/* 定义GPIO引脚结构体，用于和上层进行通信 */
typedef struct gpio_ctrl_blk{
    int pin;
    int value;
}gpio_cblk_t;


#define HD1650_DEV_ID 'k'
#define GET_KEY             _IOWR (HD1650_DEV_ID,0x34,int)


/* 定义延时函数，用于i2c通信 */
#define DELAY_BUILD()    udelay(10)
#define DELAY()            udelay(10)

/* this define copy from datasheet */
#define CMD_SYSOFF    0x4800
#define CMD_SYSON    0x4801
#define CMD_SLEEPOFF    0x4800
#define CMD_SLEEPON    0x4804
#define CMD_7SEGON    0x4809
#define CMD_8SEGON    0x4801

#define CMD_7SEGON1    0x4819
#define CMD_7SEGON2    0x4829
#define CMD_7SEGON3    0x4839
#define CMD_7SEGON4    0x4849
#define CMD_7SEGON5    0x4859
#define CMD_7SEGON6    0x4869
#define CMD_7SEGON7    0x4879
#define CMD_7SEGON8    0x4809

#define CMD_8SEGON1    0x4811
#define CMD_8SEGON2    0x4821
#define CMD_8SEGON3    0x4831
#define CMD_8SEGON4    0x4841
#define CMD_8SEGON5    0x4851
#define CMD_8SEGON6    0x4861
#define CMD_8SEGON7    0x4871
#define CMD_8SEGON8    0x4801

#define CMD_DIG0(x)    0x6800 | (x)
#define CMD_DIG1(x)    0x6A00 | (x)
#define CMD_DIG2(x)    0x6C00 | (x)
#define CMD_DIG3(x)    0x6E00 | (x)
#define CMD_GETKEY    0x4F00

/*show define*/
/******************************************************************
  a
  __
f|__|b
e|__|c .dop  中间那段为g
d
*******************************************************************/

//数码管末一段的值
#define BA        0x1
#define BB        0x1<<1
#define BC        0x1<<2
#define BD        0x1<<3
#define BE        0x1<<4
#define BF        0x1<<5
#define BG        0x1<<6
#define BP        0x1<<7

//数码管显示的字符的值
#define TM_A        BF | BA | BB | BG | BE | BC
#define TM_B        BF | BE | BG | BD | BC
#define TM_C        BG | BE | BD
#define TM_D        BB | BC | BD | BE | BG
#define TM_E        BA | BF | BG | BE | BD
#define TM_G        BA | BF | BE | BD | BC
#define TM_F        BA | BF | BG | BE
#define TM_H        BF | BE | BG | BC
#define TM_I        BB | BC
#define TM_J        BB | BC | BD | BE
#define TM_K        BF | BG | BE | BC | BB
#define TM_L        BF | BE | BD
#define TM_M        0
#define TM_N        BE | BG | BC
#define TM_O        BG | BC | BD | BE
#define TM_P        BA | BB |BG | BF |BE
#define TM_Q        BF | BA | BB | BG | BC
#define TM_R        BE | BG
#define TM_S        BA | BF | BG | BC | BD
#define TM_T        BF | BG | BE | BD
#define TM_U        BF | BE | BD | BC | BB
#define TM_V        BE | BD | BC
#define TM_W        0
#define TM_X        0
#define TM_Y        0
#define TM_Z        0

#define TM_0        BA | BB | BC | BD | BE | BF
#define TM_1        BB | BC
#define TM_2        BA | BB | BG | BE | BD
#define TM_3        BA | BB | BC | BD | BG
#define TM_4        BF | BG | BB | BC
#define TM_5        BA | BF | BG | BC | BD
#define TM_6        BA | BF | BG | BE | BD | BC
#define TM_7        BF | BA | BB | BC
#define TM_8        BA | BB | BC | BD | BE | BF | BG
#define TM_9        BA | BB | BC | BD | BG | BF

unsigned char TM_NUM[] = {TM_0, TM_1, TM_2, TM_3, TM_4,
TM_5, TM_6, TM_7, TM_8, TM_9}; //定义键值

unsigned char TM_CHAR[] = {TM_A, TM_B, TM_C, TM_D, TM_E, TM_F, TM_G,
TM_H, TM_I, TM_J, TM_K, TM_L, TM_M, TM_N, 
TM_O, TM_P, TM_Q, TM_R, TM_S, TM_T, TM_U, 
TM_V, TM_W, TM_X, TM_Y, TM_Z};


/*对i2c操作函数*/
static void i2c_start(void);
static void i2c_stop(void);
static void i2c_send(unsigned char data);
static unsigned char i2c_recv(unsigned char *data);
static int i2c_get_ack(void);
static int i2c_get_ack_getkey(void);


static void CLK_OUT(void); 
static void SDA_IN(void);
static void SDA_OUT(void);
static int GET_SDA(void);
static void CLK_H(void);
static void CLK_L(void);
static void SDA_H(void);
static void SDA_L(void);

static unsigned char hd1650_sendcmd(unsigned short cmd);


/*************函数实现******************/


/* 设置时钟引脚为输出引脚 */
static void CLK_OUT(void) 
{
    gpio_cblk_t gpio_dev;
    gpio_dev.pin = GPIO_PC31;
    gpio_dev.value = 1;

    at91_set_gpio_output(gpio_dev.pin,gpio_dev.value); 
}

/* 设置数据引脚为输出引脚 */
static void SDA_OUT(void)
{
    gpio_cblk_t gpio_dev;

    gpio_dev.pin = GPIO_PC30;
    gpio_dev.value = 1;
    
    at91_set_gpio_output(gpio_dev.pin,gpio_dev.value);
}

/* 设置数据引脚为输入引脚 */
static void SDA_IN(void)
{
    gpio_cblk_t gpio_dev;

    gpio_dev.pin = GPIO_PC30;
    gpio_dev.value = 1;

    at91_set_gpio_input(gpio_dev.pin,gpio_dev.value);
}

/* 取数据引脚的值 */
static int GET_SDA(void)
{
    gpio_cblk_t gpio_dev;

    gpio_dev.pin = GPIO_PC30;
    gpio_dev.value = at91_get_gpio_value(gpio_dev.pin);

    return gpio_dev.value;
}

/* 设置时钟引脚为高 */
static void CLK_H(void)
{
    gpio_cblk_t gpio_dev;
    gpio_dev.pin = GPIO_PC31;
    gpio_dev.value = 1;

    at91_set_gpio_value(gpio_dev.pin,gpio_dev.value);
}

/* 设置时钟引脚为低*/
static void CLK_L(void)
{
    gpio_cblk_t gpio_dev;
    gpio_dev.pin = GPIO_PC31;
    gpio_dev.value = 0;

    at91_set_gpio_value(gpio_dev.pin,gpio_dev.value);
}

/* 设置数据引脚为高 */
static void SDA_H(void)
{
    gpio_cblk_t gpio_dev;
    gpio_dev.pin = GPIO_PC30;
    gpio_dev.value = 1;

    at91_set_gpio_value(gpio_dev.pin,gpio_dev.value);
}

/* 设置数据引脚为低 */
static void SDA_L(void)
{
    gpio_cblk_t gpio_dev;
    gpio_dev.pin = GPIO_PC30;
    gpio_dev.value = 0;

    at91_set_gpio_value(gpio_dev.pin,gpio_dev.value);
}




/*****************************global function *********************************/
void hd1650_init(void)
{
    hd1650_sendcmd(CMD_8SEGON);

    /* clear 4 segment */
    hd1650_sendcmd(CMD_DIG0(0x00));
    hd1650_sendcmd(CMD_DIG1(0x00));
    hd1650_sendcmd(CMD_DIG2(0x00));
    hd1650_sendcmd(CMD_DIG3(0x00));
}

unsigned char asc2code(unsigned char src)
{
    
    if(src <= 9)
        return TM_NUM[src];
    else if(src >= '0' && src <= '9')
        return TM_NUM[src - '0'];
    else if(src >= 'a' && src <= 'z')
        return TM_CHAR[src - 'a'];
    else if(src >= 'A' && src <= 'Z')
        return TM_CHAR[src - 'A'];
    else
        return 0;
    
}

/*data : 0-6
 * pos: 2
 * dot_flag:数码管的点的亮灭*/
void hd1650_show_each(unsigned char data, unsigned char pos,unsigned char dot_flag)
{
    unsigned char tmpData;
    //tmpData = asc2code(data);
    switch(pos)
    {
        case 1:
            hd1650_sendcmd(CMD_DIG0(tmpData));
            break;
        case 2:
            if(dot_flag)
                hd1650_sendcmd(CMD_DIG1(tmpData|0x80));
            else
                //hd1650_sendcmd(CMD_DIG1(tmpData&0x7f));
                hd1650_sendcmd(CMD_DIG1(data));
            break;
        case 3:
            hd1650_sendcmd(CMD_DIG2(tmpData));
            break;
        case 4:
            hd1650_sendcmd(CMD_DIG3(tmpData));
            break;
    }
}



unsigned char hd1650_getkey(unsigned char *key)
{
    unsigned char tmp = 0;

    
    tmp = hd1650_sendcmd( CMD_GETKEY );

    if((tmp & 0x40)== 0)
        tmp = 0x2e;

    if( key )
        *key = tmp;

    return tmp;
}



/*****************************local function implemention*********************************/
/*****************************DO NOT MODIFY*********************************/
static void i2c_start(void)
{
    CLK_OUT();
    SDA_OUT();

    SDA_H();
    DELAY();
    CLK_H();
    DELAY_BUILD();
    SDA_L();
    DELAY();
}

static void i2c_stop(void)
{
    SDA_OUT();
    SDA_L();
    DELAY();

    CLK_H();
    DELAY_BUILD();
    SDA_H();
    DELAY();


}

/* MSB */
static void i2c_send(unsigned char data)
{
    unsigned char i = 0;
    for(; i < 8 ; i++)
    {
        CLK_L();
        DELAY_BUILD();
        if( data & 0x80 )
            SDA_H();
        else
            SDA_L();
        data <<= 1;
        DELAY();
        CLK_H();
        DELAY();
    }
}

static unsigned char i2c_recv(unsigned char *data)
{
    unsigned char i = 0, tmp=0;
    SDA_IN();
    for(; i < 8 ; i++)
    {
        CLK_L();
        DELAY();
        CLK_H();
        DELAY_BUILD();
        tmp <<= 1;
        tmp |= GET_SDA();
        
        DELAY();
    }
    SDA_OUT();

    if( data )
        *data = tmp;
    return tmp;
}

static int i2c_get_ack(void)
{
    int i = 30;

    CLK_L();
    SDA_IN();
    DELAY_BUILD();
    
    CLK_H();
    DELAY();
    while(GET_SDA() && i-- );
    CLK_L();
    SDA_OUT();

    return 1;/*!!!Fixme. this should return the right value, but sometimes the ack cannot get */
}

static int i2c_get_ack_getkey(void)
{
    int i = 30;

    CLK_L();
    SDA_IN();
    DELAY_BUILD();
    
    CLK_H();
    DELAY();
    while(!GET_SDA() && i-- );
    CLK_L();
    SDA_OUT();

    return 1;/*!!!Fixme. this should return the right value, but sometimes the ack cannot get */
}


static unsigned char hd1650_sendcmd(unsigned short cmd)
{
    unsigned char tmp_data = cmd>>8;

    i2c_start();
    i2c_send(tmp_data);
    if(1 != i2c_get_ack() )
    {
        /* printk some error
        * hd1650 didnot send the ack
        */
    }

    if( cmd == CMD_GETKEY )
    {
        i2c_recv(&tmp_data);
        if(1 != i2c_get_ack_getkey())
        {
            /* printk some error
            * hd1650 didnot send the ack
            */
        }
    }else{
        tmp_data = cmd&0x0ff;
        i2c_send(tmp_data);
        if(1 != i2c_get_ack())
        {
            /* printk some error
            * hd1650 didnot send the ack
            */
        }
    }

    
    i2c_stop();

    return tmp_data;/* just valid for the CMD_GETKEY */
}




/*******END OF THE FILE *********/

static int hd1650_ctrl_drv_open(struct node *node, struct file *file )
{
    return 0;
}

static int hd1650_ctrl_drv_release(struct node *node, struct file *file )
{
    return 0;
}

static long hd1650_ctrl_drv_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    unsigned char key = 0;

    int ret = 0;
    
    switch (cmd) {
    case GET_KEY:
            hd1650_getkey(&key);
            ret = put_user(key,(int *)arg);
            break;
    default:
        return -EINVAL;

    }

    
    
    return 0;
}

static struct file_operations hd1650_ctl_drv_fileops = {
    .owner = THIS_MODULE,
    .open = hd1650_ctrl_drv_open,
    .unlocked_ioctl = hd1650_ctrl_drv_unlocked_ioctl,
    .release = hd1650_ctrl_drv_release
};

static struct miscdevice hd1650_dev = {
    MISC_DYNAMIC_MINOR,
    "hd1650_dev",
    &hd1650_ctl_drv_fileops,
};
int gpio_ctrl_drv_module_init(void)
{
    int ret = 0;


    ret = misc_register(&hd1650_dev);
    if(ret != 0)
    {
        ret = -EFAULT;
        return ret;
    }
    hd1650_init();
    hd1650_show_each(0x40 ,2,0);
    printk("hd1650_drv_init ok
");
    return 0;
}


void gpio_ctrl_drv_module_exit(void)
{

    misc_deregister(&hd1650_dev);
    printk("gpio_drv_exit ok
");
}



module_init(gpio_ctrl_drv_module_init);
module_exit(gpio_ctrl_drv_module_exit);
MODULE_LICENSE("GPL");