以非 root 用户身份访问 beaglebone 上的 GPIO？

Question

我四处询问，但我尝试的任何 udev 规则都不起作用。

我需要的是能够访问 gpio 引脚作为 root 以外的其他用途。

例如，从 Adafruit 执行 python 脚本，它应该从传感器读取温度，我得到了这个：

$ python Adafruit_Python_DHT/examples/simpletest.py 
Traceback (most recent call last):
  File "Adafruit_Python_DHT/examples/simpletest.py", line 39, in <module>
    humidity, temperature = Adafruit_DHT.read_retry(sensor, pin)
  File "build/bdist.linux-armv7l/egg/Adafruit_DHT/common.py", line 90, in read_retry
  File "build/bdist.linux-armv7l/egg/Adafruit_DHT/common.py", line 77, in read
  File "build/bdist.linux-armv7l/egg/Adafruit_DHT/Beaglebone_Black.py", line 213, in read
RuntimeError: Error accessing GPIO. Make sure program is run as root with sudo!

我尝试了许多不同的技巧来解决这个问题，但它只有在我以 root 身份使用时才有效 我试过这个：https://gist.github.com/metasoarous/a7308779837f9dcba662 和这个https://github.com/metasoarous/strange-coop/tree/master/etc

还有其他一些 udev/rules.d，但到目前为止没有任何效果...

知道怎么改吗？

Answer 1

我根据this 尝试了以下说明并成功了：

1. 运行nano /etc/udev/rules.d/80-gpio-permissions.rules

2. 写

   KERNEL=="gpio*", SUBSYSTEM=="gpio", ACTION=="add", PROGRAM="/usr/local/bin/udev-gpio-permissions.sh"
   

3. 运行nano /usr/local/bin/udev-gpio-permissions.sh

4. 复制

   #!/bin/bash
   
   # Result: chown debian:root /sys/class/gpio
   
   chown -R debian:root /sys/devices/gpio
   chown -R debian:root /sys/class/gpio
   chown -R debian:root /sys/devices/platform/ocp
   chown -R debian:root /sys/class/pwm
   
   #GPIO ( active_low device direction edge power subsystem uevent value )
   find /sys/class/gpio -type d -exec chmod 2770 {} \;
   find /sys/class/gpio -name "direction" -exec chmod 0660 {} \;
   find /sys/class/gpio -name "edge" -exec chmod 0660 {} \;
   find /sys/class/gpio -name "value" -exec chmod 0660 {} \;
   find /sys/class/gpio -name "active_low" -exec chmod 0660 {} \;
   find /sys/class/gpio -name "device" -exec chmod 0660 {} \;
   find /sys/class/gpio -name "power" -exec chmod 0660 {} \;
   find /sys/class/gpio -name "subsystem" -exec chmod 0660 {} \;
   
   chmod 0220 /sys/class/gpio/export
   chmod 0220 /sys/class/gpio/unexport
   
   find /sys/class/gpio -name "uevent" -exec chmod 0660 {} \;
   find /sys/class/gpio -name "autosuspend_delay_ms" -exec chmod 0660 {} \;
   find /sys/class/gpio -name "control" -exec chmod 0660 {} \;
   

5. 运行 chmod +x /usr/local/bin/udev-gpio-permissions.sh

6. 运行 udevadm control --reload-rules

7. 重启