Linux UserButtons
From Variscite Wiki
User Buttons
To test any event device, run the following and the available devices will be listed and numbered:
# evtest
Then, select the device event number you want to test, and use the device - in this case, push the button.
For example, on the VAR-SOM-MX7:
root@imx7-var-som:~# evtest
No device specified, trying to scan all of /dev/input/event*
Available devices:
/dev/input/event0: 30370000.snvs:snvs-powerkey
/dev/input/event1: ADS7846 Touchscreen
/dev/input/event2: ft5x06_ts
/dev/input/event3: gpio-keys
Select the device event number [0-3]: 3
Input driver version is 1.0.1
Input device ID: bus 0x19 vendor 0x1 product 0x1 version 0x100
Input device name: "gpio-keys"
Supported events:
Event type 0 (EV_SYN)
Event type 1 (EV_KEY)
Event code 102 (KEY_HOME)
Event code 139 (KEY_MENU)
Event code 158 (KEY_BACK)
Properties:
Testing ... (interrupt to exit)
Event: time 1474554375.147272, type 1 (EV_KEY), code 158 (KEY_BACK), value 1
Event: time 1474554375.147272, -------------- SYN_REPORT ------------
Event: time 1474554375.247234, type 1 (EV_KEY), code 158 (KEY_BACK), value 0
Event: time 1474554375.247234, -------------- SYN_REPORT ------------
Event: time 1474554376.217208, type 1 (EV_KEY), code 102 (KEY_HOME), value 1
Event: time 1474554376.217208, -------------- SYN_REPORT ------------
Event: time 1474554376.337219, type 1 (EV_KEY), code 102 (KEY_HOME), value 0
Event: time 1474554376.337219, -------------- SYN_REPORT ------------
Event: time 1474554377.317246, type 1 (EV_KEY), code 139 (KEY_MENU), value 1
Event: time 1474554377.317246, -------------- SYN_REPORT ------------
Event: time 1474554377.427249, type 1 (EV_KEY), code 139 (KEY_MENU), value 0
Event: time 1474554377.427249, -------------- SYN_REPORT ------------