三轴陀螺仪MPU3050驱动解析
MPU3050是invensense公司的三轴陀螺仪芯片,三轴陀螺仪最大的作用就是“测量角速度，以判别物体的运动状态，所以也称为运动传感器.
下图是MPU3050的系统框图,芯片有1个中断引脚,可以通过i2c来控制,获取x Gyro，y Gyro，z Gyro
设备驱动中用mpu3050_sensor结构体来描述MPU3050设备对象(对象中包含i2c客户端及输入设备来处理获取的x,y,z轴数据的传递)
struct mpu3050_sensor { //mpu3050传感器
struct i2c_client *client; //i2c客户端
struct device *dev; //设备文件
struct input_dev *idev; //输入设备
};struct axis_data { //轴数据
s16 x; //x轴
s16 y; //y轴
s16 z; //z轴
};module_i2c_driver(mpu3050_i2c_driver);static struct i2c_driver mpu3050_i2c_driver = {
.driver = {
.name = "mpu3050",
.owner = THIS_MODULE,
.pm = &mpu3050_pm,
.of_match_table = mpu3050_of_match,
},
.probe = mpu3050_probe, //i2c probe方法
.remove = __devexit_p(mpu3050_remove),
.id_table = mpu3050_ids,
};i2c设备与驱动匹配需要在板级驱动中注册i2c驱动
htc one max板的做法如下
static struct i2c_board_info __initdata mpu3050_GSBI12_boardinfo[] = {
{
I2C_BOARD_INFO("mpu3050", 0xD0 >> 1),
.irq = PM8921_GPIO_IRQ(PM8921_IRQ_BASE, PM_GYRO_INT),
.platform_data = &mpu3050_data,
},
};i2c_register_board_info(MSM8064_GSBI2_QUP_I2C_BUS_ID,
mpu3050_GSBI12_boardinfo,
ARRAY_SIZE(mpu3050_GSBI12_boardinfo));注册i2c板级信息
static int __devinit mpu3050_probe(struct i2c_client *client,const struct i2c_device_id *id)
{
struct mpu3050_sensor *sensor; //mpu3050传感器
struct input_dev *idev; //输入设备
int ret;
int error;
sensor = kzalloc(sizeof(struct mpu3050_sensor), GFP_KERNEL); //分配mpu3050数据
idev = input_allocate_device(); //分配输入设备
if (!sensor || !idev) {
dev_err(&client->dev, "failed to allocate driver data\n");
error = -ENOMEM;
goto err_free_mem;
}
sensor->client = client; //捆绑i2c客户端
sensor->dev = &client->dev; //捆绑设备文件
sensor->idev = idev; //捆绑输入设备
mpu3050_set_power_mode(client, 1); //设置设备正常电压模式
msleep(10); //睡眠
ret = i2c_smbus_read_byte_data(client, MPU3050_CHIP_ID_REG);//获取0x00寄存器值
if (ret < 0) {
dev_err(&client->dev, "failed to detect device\n");
error = -ENXIO;
goto err_free_mem;
}
if (ret != MPU3050_CHIP_ID) { //判断芯片ID值(0x69)是否MPU3050
dev_err(&client->dev, "unsupported chip id\n");
error = -ENXIO;
goto err_free_mem;
}
idev->name = "MPU3050"; //设置输入设备名
idev->id.bustype = BUS_I2C; //输入设备使用i2c总线
idev->dev.parent = &client->dev; //设置i2c设备为输入设备父设备
idev->open = mpu3050_input_open; //输入设备打开方法
idev->close = mpu3050_input_close; //输入设备关闭方法
__set_bit(EV_ABS, idev->evbit); //设置绝对位移事件标志位,设置各轴数据范围
input_set_abs_params(idev, ABS_X,MPU3050_MIN_VALUE, MPU3050_MAX_VALUE, 0, 0);
input_set_abs_params(idev, ABS_Y,MPU3050_MIN_VALUE, MPU3050_MAX_VALUE, 0, 0);
input_set_abs_params(idev, ABS_Z,MPU3050_MIN_VALUE, MPU3050_MAX_VALUE, 0, 0);
input_set_drvdata(idev, sensor); //&idev->dev->p->driver_data=sensor
pm_runtime_set_active(&client->dev);
error = mpu3050_hw_init(sensor); //初始化MPU3050固件
if (error)
goto err_pm_set_suspended;
//申请中断,上升沿触发
error = request_threaded_irq(client->irq,NULL, mpu3050_interrupt_thread,IRQF_TRIGGER_RISING,"mpu3050", sensor);
if (error) {
dev_err(&client->dev,"can't get IRQ %d, error %d\n", client->irq, error);
goto err_pm_set_suspended;
}
error = input_register_device(idev); //注册输入设备
if (error) {
dev_err(&client->dev, "failed to register input device\n");
goto err_free_irq;
}
pm_runtime_enable(&client->dev);
pm_runtime_set_autosuspend_delay(&client->dev, MPU3050_AUTO_DELAY);
return 0;
err_free_irq:
free_irq(client->irq, sensor);
err_pm_set_suspended:
pm_runtime_set_suspended(&client->dev);
err_free_mem:
input_free_device(idev);
kfree(sensor);
return error;
}设置电源模式:mpu3050有两种电压模式val=1为正常模式,val=0为低功耗模式
static void mpu3050_set_power_mode(struct i2c_client *client, u8 val)
{
u8 value;
value = i2c_smbus_read_byte_data(client, MPU3050_PWR_MGM);//获取0x3E寄存器数据
//根据val值设置0x3E寄存器第6位SLEEP
value = (value & ~MPU3050_PWR_MGM_MASK) |
(((val << MPU3050_PWR_MGM_POS) & MPU3050_PWR_MGM_MASK) ^ MPU3050_PWR_MGM_MASK);
i2c_smbus_write_byte_data(client, MPU3050_PWR_MGM,value);//设置0x3E寄存器数据
}static int __devinit mpu3050_hw_init(struct mpu3050_sensor *sensor)
{
struct i2c_client *client = sensor->client; //获取i2c客户端
int ret;
u8 reg;
/* Reset 设置0x3E寄存器第7位H_RESET*/
ret = i2c_smbus_write_byte_data(client, MPU3050_PWR_MGM,MPU3050_PWR_MGM_RESET);
if (ret < 0)
return ret;
//获取0x3E寄存器值
ret = i2c_smbus_read_byte_data(client, MPU3050_PWR_MGM);
if (ret < 0)
return ret;
ret &= ~MPU3050_PWR_MGM_CLKSEL; //清除0x3E寄存器0~2位CLK_SET值
ret |= MPU3050_PWR_MGM_PLL_Z; //设置0x3E寄存器CLK_SET值为0x03
ret = i2c_smbus_write_byte_data(client, MPU3050_PWR_MGM,ret);//设置0x3E寄存器
if (ret < 0)
return ret;
/* Output frequency divider. The poll interval 设置0x15寄存器值为119输出分频值*/
ret = i2c_smbus_write_byte_data(client, MPU3050_SMPLRT_DIV,MPU3050_DEFAULT_POLL_INTERVAL - 1);
if (ret < 0)
return ret;
/* Set low pass filter and full scale 设置低通滤波器和全扫描范围*/
reg = MPU3050_DEFAULT_FS_RANGE;
reg |= MPU3050_DLPF_CFG_42HZ << 3;
reg |= MPU3050_EXT_SYNC_NONE << 5;
ret = i2c_smbus_write_byte_data(client, MPU3050_DLPF_FS_SYNC, reg);//设置0x16寄存器
if (ret < 0)
return ret;
return 0;
}static irqreturn_t mpu3050_interrupt_thread(int irq, void *data)
{
struct mpu3050_sensor *sensor = data; //获取mpu3050传感器
struct axis_data axis;
mpu3050_read_xyz(sensor->client, &axis); //获取xyz轴数值
input_report_abs(sensor->idev, ABS_X, axis.x); //上报x轴事件
input_report_abs(sensor->idev, ABS_Y, axis.y); //上报y轴事件
input_report_abs(sensor->idev, ABS_Z, axis.z); //上报z轴事件
input_sync(sensor->idev); //同步事件
return IRQ_HANDLED;
}获取xyz轴数值,通过i2c命令去获取便可
static int mpu3050_xyz_read_reg(struct i2c_client *client,u8 *buffer, int length)
{
/*
* Annoying we can't make this const because the i2c layer doesn't
* declare input buffers const.
*/
char cmd = MPU3050_XOUT_H; //i2c读取0x1D~0x22寄存器值
struct i2c_msg msg[] = {
{
.addr = client->addr,
.flags = 0,
.len = 1,
.buf = &cmd,
},
{
.addr = client->addr,
.flags = I2C_M_RD,
.len = length,
.buf = buffer,
},
};
return i2c_transfer(client->adapter, msg, 2);
}static int mpu3050_input_open(struct input_dev *input)
{
struct mpu3050_sensor *sensor = input_get_drvdata(input); //获取mpu3050传感器
int error;
pm_runtime_get(sensor->dev);
/* Enable interrupts
使能中断,设置0x17寄存器MPU_RDY_EN,DMP_DONE_EN,RAW_RDY_EN位*/
error = i2c_smbus_write_byte_data(sensor->client, MPU3050_INT_CFG,
MPU3050_LATCH_INT_EN | MPU3050_RAW_RDY_EN | MPU3050_MPU_RDY_EN);
if (error < 0) {
pm_runtime_put(sensor->dev);
return error;
}
return 0;
}