28BYJ-48 电机驱动(Linux)

17、28BYJ-48 电机驱动

什么，学完了pinctrl子系统和GPIO子系统还只会点灯？
今天就来个高级点的点灯

这个电机驱动程序说白了就是点灯

1、28BYJ-48 电机是四相八拍电机，所以需要4个GPIO来控制

简介：

28：步进电机的有效最大外径是28毫米

B：表示是步进电机

Y：表示是永磁式

J：表示是减速型（减速比1:64)

48：表示四相八拍

内部结构示意图

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1、相数：是指产生不同对极N、S磁场的激磁线圈对数。常用m表示例如上图有四对线圈 A、B、C、D

2、拍数：完成一个磁场周期性变化所需脉冲数，以四相电机为例，

有单相四拍运行方式即A-B-C-D，

有双相四拍运行方式即AB-BC-CD-DA

有四相八拍运行方式即A-AB-B-BC-C-CD-D-DA

3、步进角：

步进电机的定子绕组每改变一次通电状态，转子转过的角度称步进角。

转子磁极数越多，步进角越小

定子相数越多，步进角越小

通电方式节拍越多，步进角越小

例如八拍模式下 360/(4 * 8 * 2) = 5.625

关于启动频率，也就是pps 这里间隔时间最好是大于1200us

与开发板的管脚连接

第一步在pinctrl子系统中，对这几个管脚进行配置

exynos4412-pinctrl.dtsi 文件中

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     mymoter: mymoter {samsung,pins = "gpj0-3", "gpj0-4", "gpj0-5", "gpj0-6";samsung,pin-function = <EXYNOS_PIN_FUNC_OUTPUT>; //设置为输出模式samsung,pin-val = <0x0>;  //默认输出低电平//  samsung,pin-pud = <EXYNOS_PIN_PULL_UP>;};

2、第二步在根节点下添加MOTOR节点

exynos4412-itop-elite.dts 文件中在根节点中添加节点

 /*motor*/my_motor:my_motor{compatible = "motor";         //描述pinctrl-names = "default";       pinctrl-0 = <&mymotor>;      status = "okay"/*GPIO管脚  "gpj0-3", "gpj0-4", "gpj0-5", "gpj0-6";*/motorA-gpios = <&gpj0 3 GPIO_ACTIVE_HIGH>;  //GPJ0_3 GPIO_ACTIVE_HIGH 表示高电平有效motorB-gpios = <&gpj0 4 GPIO_ACTIVE_HIGH>;motorC-gpios = <&gpj0 5 GPIO_ACTIVE_HIGH>;motorD-gpios = <&gpj0 6 GPIO_ACTIVE_HIGH>;}

3、编写driver程序

#include <linux/init.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/of.h>
#include <linux/device.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/cdev.h>#include <linux/pinctrl/consumer.h>
#include <dt-bindings/pinctrl/samsung.h>#include <linux/of_gpio.h>/*  字符设备框架1、注册 platform driver2、构建file_operations3、获取硬件资源4、注册字符设备驱动4、生成字符设备节点
*/
/*  定义各个管脚的命令
*/
#define MOTOR_CMD_A _IOW('M',0,long)
#define MOTOR_CMD_B _IOW('M',1,long)
#define MOTOR_CMD_C _IOW('M',2,long)
#define MOTOR_CMD_D _IOW('M',3,long)struct device *device_cdev;
struct class *class_cdev;int GPIO_ID_A;
int GPIO_ID_B;
int GPIO_ID_C;
int GPIO_ID_D;int motor_open(struct inode *inode, struct file *file)
{printk("open is success!\n");return 0;
}
int motor_release (struct inode *inode, struct file *file)
{printk("release is success!\n");return 0;
}
long motor_ioctrl(struct file *file, unsigned int cmd, unsigned long value)
{switch(cmd){case MOTOR_CMD_A:gpio_set_value(GPIO_ID_A, value);break;case MOTOR_CMD_B:gpio_set_value(GPIO_ID_B, value);break;     case MOTOR_CMD_C:gpio_set_value(GPIO_ID_C, value);break;case MOTOR_CMD_D:gpio_set_value(GPIO_ID_D, value);break;}
}/*2、获取硬件资源 */
int motor_probe(struct platform_device *pdev)
{int ret;/*1、获取GPIO号*/GPIO_ID_A = of_get_named_gpio(pdev->dev.of_node, "motorA-gpios", 0);//index=0 ,因为在设备树中只引用了一个if (GPIO_ID_A < 0){printk("of get named gpio is error!\n");return -1;}GPIO_ID_B = of_get_named_gpio(pdev->dev.of_node, "motorB-gpios", 0);//index=0 ,因为在设备树中只引用了一个if (GPIO_ID_B < 0){printk("of get named gpio is error!\n");return -1;}GPIO_ID_C = of_get_named_gpio(pdev->dev.of_node, "motorC-gpios", 0);//index=0 ,因为在设备树中只引用了一个if (GPIO_ID_C< 0){printk("of get named gpio is error!\n");return -1;}GPIO_ID_D = of_get_named_gpio(pdev->dev.of_node, "motorD-gpios", 0);//index=0 ,因为在设备树中只引用了一个if (GPIO_ID_D< 0){printk("of get named gpio is error!\n");return -1;}/*2、申请一个GPIO管脚*/ret = gpio_request(GPIO_ID_A, "motor_A_GPIO");if (ret != 0){printk("gpio request is error!\n");return -1;}ret = gpio_request(GPIO_ID_B, "motor_B_GPIO");if (ret != 0){printk("gpio request is error!\n");return -1;}ret = gpio_request(GPIO_ID_C, "motor_C_GPIO");if (ret != 0){printk("gpio request is error!\n");return -1;}ret = gpio_request(GPIO_ID_D, "motor_D_GPIO");if (ret != 0){printk("gpio request is error!\n");return -1;}/*3、 将管脚设置为输出*//* 这里先不设置，因为在pinctrl复用中已经将管脚设置为了OUTPUT*/return 0;
}
int motor_remove(struct platform_device *pdev)
{return 0;
}struct of_device_id of_match_table = {      // 与设备树节点进行匹配.compatible = "motor"
};/*1、初始化platform driver*/
struct platform_driver pdev = {.probe = motor_probe,          // 与 of_match_table 匹配成功后进入probe函数获取硬件资源.remove = motor_remove,.driver = {.name = "motor",     //无设备树时 使用.name 与device进行匹配.owner = THIS_MODULE,.of_match_table = &of_match_table,}
};
//3、注册字符设备驱动
/*3.1 分配设备号*/
dev_t dev_number;
/*3.2 定义cdev*/
struct cdev cdev_;/*3.3 构建file_operation结构体*/
struct file_operations fop = {.owner = THIS_MODULE,.open    = motor_open,.release = motor_release,.unlocked_ioctl = motor_ioctrl
};
static int char_driver_init(void)
{/*1、注册platform driver*/int ret = platform_driver_register(&pdev);if (0 != ret){   printk("platform driver register is error!\n");return -1;}/*3.1 分配设备号(动态分配设备号)*/ret = alloc_chrdev_region(&dev_number, 0, 1, "my_motor");if (0 != ret){printk("alloc chrdev region is error!\n");return ret;}/*3.4 初始化cdev*/cdev_.owner = THIS_MODULE;cdev_init(&cdev_, &fop);/*3.5 注册字符设备到内核*/ret = cdev_add(&cdev_, dev_number, 1);if (0 != ret){printk("cdev add is error!\n");return -1;}/*4、生成设备节点*//*4.1 创建字符设备类*/class_cdev =  class_create(THIS_MODULE, "motor");if (NULL == class_cdev){printk("class create is error!\n");return -1;}/*生成设备节点*/device_cdev = device_create (class_cdev, NULL, dev_number, NULL,  "my_motor");if (NULL == device_cdev){printk("device create is error!\n");}return 0;
};static void char_driver_exit(void)
{gpio_free(GPIO_ID_A);  gpio_free(GPIO_ID_B);    gpio_free(GPIO_ID_C);    gpio_free(GPIO_ID_D);    //释放GPIOdevice_destroy(class_cdev, dev_number); // 卸载设备节点class_destroy(class_cdev);              //卸载设备类cdev_del(&cdev_);                       //卸载cdev//   iounmap(led_con);                       // 取消地址映射//   iounmap(led_dat);                   unregister_chrdev_region(dev_number, 1);// 注销设备号 platform_driver_unregister(&pdev);       // 注销platform driver}module_init(char_driver_init);
module_exit(char_driver_exit);
MODULE_LICENSE("GPL");

4、应用程序

#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <sys/types.h>#include <sys/ioctl.h>
#define MOTOR_DEV "/dev/my_motor"/* 一个节拍 转动 5.625*/#define MOTOR_CMD_A _IOW('M',0,long)
#define MOTOR_CMD_B _IOW('M',1,long)
#define MOTOR_CMD_C _IOW('M',2,long)
#define MOTOR_CMD_D _IOW('M',3,long)#define HIGH 1
#define LOW 0#define NUMBER 10000
#define SPEED 1500
//SPEED 越小转速越快
int fd;
int motor_off(void)
{ioctl(fd, MOTOR_CMD_A, LOW);ioctl(fd, MOTOR_CMD_B, LOW);ioctl(fd, MOTOR_CMD_C, LOW);ioctl(fd, MOTOR_CMD_D, LOW);}
static int meter_turn(int n)
{switch(n){case 0:ioctl(fd, MOTOR_CMD_A, LOW);ioctl(fd, MOTOR_CMD_B, HIGH);ioctl(fd, MOTOR_CMD_C, HIGH);ioctl(fd, MOTOR_CMD_D, HIGH);break;case 1:ioctl(fd, MOTOR_CMD_A, LOW);ioctl(fd, MOTOR_CMD_B, LOW);ioctl(fd, MOTOR_CMD_C, HIGH);ioctl(fd, MOTOR_CMD_D, HIGH);break;case 2:ioctl(fd, MOTOR_CMD_A, HIGH);ioctl(fd, MOTOR_CMD_B, LOW);ioctl(fd, MOTOR_CMD_C, HIGH);ioctl(fd, MOTOR_CMD_D, HIGH);break;case 3:ioctl(fd, MOTOR_CMD_A, HIGH);ioctl(fd, MOTOR_CMD_B, LOW);ioctl(fd, MOTOR_CMD_C, LOW);ioctl(fd, MOTOR_CMD_D, HIGH);break;case 4:ioctl(fd, MOTOR_CMD_A, HIGH);ioctl(fd, MOTOR_CMD_B, HIGH);ioctl(fd, MOTOR_CMD_C, LOW);ioctl(fd, MOTOR_CMD_D, HIGH);break;case 5:ioctl(fd, MOTOR_CMD_A, HIGH);ioctl(fd, MOTOR_CMD_B, HIGH);ioctl(fd, MOTOR_CMD_C, LOW);ioctl(fd, MOTOR_CMD_D, LOW);break;case 6:ioctl(fd, MOTOR_CMD_A, HIGH);ioctl(fd, MOTOR_CMD_B, HIGH);ioctl(fd, MOTOR_CMD_C, HIGH);ioctl(fd, MOTOR_CMD_D, LOW);break;case 7:ioctl(fd, MOTOR_CMD_A, LOW);ioctl(fd, MOTOR_CMD_B, HIGH);ioctl(fd, MOTOR_CMD_C, HIGH);ioctl(fd, MOTOR_CMD_D, LOW);break;}return 0;
}void motor_direction(const char direction, int number)
{int i ;int step ;if (direction == 'R')step = -1;elsestep = 8;for (i = 0; i < number; i++){if (direction == 'R'){step++;if (step > 7)step = 0;}else {if (step == 0)step = 8;step--;}meter_turn(step);usleep(SPEED);}}
int main(int argc, char * argv[])
{fd = open(MOTOR_DEV, O_RDWR);if (-1 == fd){perror("open");return -1;}printf("open success!\n");motor_direction('L', NUMBER);motor_off();return 0;
}