Question

我正在尝试在i.MX6板上连接LSM330加速度计/陀螺仪模块。模块连接到I2C总线，设备树文件的相关部分如下：

SELECT x, Y, count(*) AS Amount  FROM Table1 
UNION ALL
SELECT X, Y, count(*) AS Amount  FROM Table2 
GROUP BY x, y;

模块显示加速度计&i2c1 { clock-frequency = <100000>; pinctrl-names = "default"; pinctrl-0 = <&pinctrl_i2c1_2>; status = "okay"; /* LSM330 motion detector (accelerometer) */ lsm330_accel: lsm330_accel@0x1e { compatible = "st,lsm330-accel"; st,drdy-int-pin = <1>; reg = <0x1e>; }; /* LSM330 motion detector (gyroscope) */ lsm330_gyro: lsm330_gyro@0x6a { compatible = "st,lsm330-gyro"; st,drdy-int-pin = <2>; reg = <0x6a>; }; };和陀螺仪/dev/iio:device0。它们还会显示为/dev/iio:device1和/sys/bus/iio/devices/iio:device0。我可以通过/sys/bus/iio/devices/iio:device1等获取传感器读数。但是，运行cat in_accel_x_raw会立即返回并且不会产生任何输出。

在互联网上搜索后，我也尝试了命令：

cat /dev/iio:device0

这应该设置通道，启用缓冲区并获取一些读数到缓冲区。据我所知，cd /sys/bus/iio/devices/iio_sysfs_trigger echo 0 > add_trigger cd /sys/bus/iio/devices/iio:device0 echo 1 > scan_elements/in_accel_x_en echo 1 > scan_elements/in_accel_y_en echo 1 > scan_elements/in_accel_z_en echo 1 > scan_elements/in_timestamp_en echo sysfstrig0 > trigger/current_trigger echo 100 > buffer/length echo 1 > buffer/enable echo 1 > /sys/bus/iio/devices/trigger0/trigger_now应显示缓冲区，但它会给我cat /dev/iio:device0。使用Device or resource busy从内核进一步读取不再有效并提供相同的错误消息。

我是linux内核的新手，我的目标是将传感器数据暴露给Android系统，以便用户可以旋转屏幕等。如何让Android从模块中获取传感器读数？

Answer 1

在查看android logcat之后，事实证明Android HAL没有读取或写入sysfs目录的权限。我最终在init.rc文件中放了一堆chmod命令，以便Android可以访问传感器数据。

# Change permissions for the LSM330 sysfs entries (accelerometer)
chmod 0666 /sys/bus/iio/devices/iio\:device0/sampling_frequency
chmod 0666 /sys/bus/iio/devices/iio\:device0/buffer/enable
chmod 0666 /sys/bus/iio/devices/iio\:device0/buffer/length
chmod 0666 /sys/bus/iio/devices/iio\:device0/trigger/current_trigger
chmod 0666 /sys/bus/iio/devices/iio\:device0/scan_elements/in_accel_x_en
chmod 0666 /sys/bus/iio/devices/iio\:device0/scan_elements/in_accel_y_en
chmod 0666 /sys/bus/iio/devices/iio\:device0/scan_elements/in_accel_z_en
chmod 0666 /sys/bus/iio/devices/iio\:device0/scan_elements/in_timestamp_en
chmod 0666 /dev/iio\:device0

希望这有助于某人。

如何从/ dev / iio中的LSM330读取数据：deviceX？

1 个答案: