GPIO口状态查询
定制的上位机（Android系统） 外接的传感器，需要使用距离感应器功能，定位问题原因，采用分段调试：
- 先查看上位机板子是否可以正常返回距离感应的状态
- 检查传输线
- 检查感应头是否正常
我这里是第一步的问题，线和感应头都正常，所以先说一下如何来返回正常的感应状态
距离传感器在检测到距离变化或者物体靠近时候会有高低电压的变化，并将信息通过数据线传输到上位机，adb shell 命令来进入到上位机，查看gpio口的状态变化
C:\Users\Administrator>adb shell
rk3399_mid:/ $ su
rk3399_mid:/ # cd sys/class/gpio
rk3399_mid:/sys/class/gpio # ls -al
total 0
drwxr-xr-x 2 root root 0 2013-01-18 16:54 .
drwxr-xr-x 73 root root 0 2013-01-18 16:54 ..
--w------- 1 root root 4096 2013-01-18 17:27 export
lrwxrwxrwx 1 root root 0 2013-01-18 17:28 gpio1058 -> ../../devices/platform/pinctrl/gpio/gpio1058
lrwxrwxrwx 1 root root 0 2013-01-18 17:14 gpio1069 -> ../../devices/platform/pinctrl/gpio/gpio1069
lrwxrwxrwx 1 root root 0 2013-01-18 16:55 gpio1154 -> ../../devices/platform/pinctrl/gpio/gpio1154
lrwxrwxrwx 1 root root 0 2013-01-18 17:14 gpiochip1000 -> ../../devices/platform/pinctrl/gpio/gpiochip1000
lrwxrwxrwx 1 root root 0 2013-01-18 17:14 gpiochip1032 -> ../../devices/platform/pinctrl/gpio/gpiochip1032
lrwxrwxrwx 1 root root 0 2013-01-18 17:14 gpiochip1064 -> ../../devices/platform/pinctrl/gpio/gpiochip1064
lrwxrwxrwx 1 root root 0 2013-01-18 17:14 gpiochip1096 -> ../../devices/platform/pinctrl/gpio/gpiochip1096
lrwxrwxrwx 1 root root 0 2013-01-18 17:14 gpiochip1128 -> ../../devices/platform/pinctrl/gpio/gpiochip1128
--w------- 1 root root 4096 2013-01-18 17:14 unexport
以上命令 查看所有gpio口的信息
格式化显示信息：
rk3399_mid:/sys/class/gpio # cat /d/gpio
rk3399_mid:/sys/class/gpio # cat /d/gpio
GPIOs 1000-1031, platform/pinctrl, gpio0:
gpio-1001 ( |WK_iqr_int ) in hi
gpio-1004 ( |bt_default_wake_host) in lo
gpio-1005 ( |power ) in hi
gpio-1008 ( |enable ) out hi
gpio-1009 ( |bt_default_reset ) out lo
gpio-1010 ( |reset ) out hi
gpio-1011 ( |? ) out hi
gpio-1012 ( |? ) out lo
GPIOs 1032-1063, platform/pinctrl, gpio1:
gpio-1034 ( |reset ) out hi
gpio-1042 ( |WK_cs_int ) out hi
gpio-1045 ( |enable ) out lo
gpio-1046 ( |vsel ) out lo
gpio-1049 ( |vsel ) out lo
gpio-1058 ( |sysfs ) in lo
GPIOs 1064-1095, platform/pinctrl, gpio2:
*gpio-1068 ( |gpio_radar ) in hi*
gpio-1069 ( |pic_int ) in hi
gpio-1083 ( |bt_default_rts ) in hi
gpio-1090 ( |bt_default_wake ) in hi
GPIOs 1096-1127, platform/pinctrl, gpio3:
gpio-1112 ( |mdio-reset ) out hi
GPIOs 1128-1159, platform/pinctrl, gpio4:
gpio-1153 ( |vcc5v0_host ) out hi
gpio-1154 ( |ex_enable ) out lo
gpio-1155 ( |enable ) out hi
其中 gpio-1068 ( |gpio_radar ) in hi
就是定制的上位机板子所用的距离传感器的命名 这里显示的hi 即为高电压状态，然后感应头的 地线与a4（我们用的是A4脚）短接 ，短接以后再次查询以上命令
gpio-1068 ( |gpio_radar ) in lo
此时 就显示的是低电量 说明板子本身没有问题，项目中用普通的传感器api调用即可
