Application note - Example code for capturing power button event on fitlet2 running Linux
From fit-PC wiki
- This application note provides an example of how to capture a power button click event on Linux.
- It has been tested with the below setup:
Device: fitlet2 CPU: Intel(R) Atom(TM) Processor E3950 BIOS: 09/17/2018 American Megatrends Inc. FLT2.0.46.01.00 OS: Debian Buster (testing) Kernel: 4.16.0-2-amd64 ISO: debian-buster-DI-alpha3-amd64-netinst.iso
fitlet2: required BIOS settings
- Press [Delete] button after power-on to enter BIOS settings
- Set BIOS -> Main -> OS selection to [Linux]
Configure power button event handling
- Login as root user (root password required):
$ su - Password:
- Ignore power button events handling by systemd, then reboot:
sed -i s/".*HandlePowerKey.*"/"HandlePowerKey=ignore"/ /etc/systemd/logind.conf reboot <pre> * Install ACPI related software if not installed yet: <pre> $ apt install acpi-support-base acpid $ service acpid status ● acpid.service - ACPI event daemon Loaded: loaded (/lib/systemd/system/acpid.service; disabled; vendor preset: enabled) Active: active (running) since Wed 2018-10-17 03:53:36 EDT; 29s ago Main PID: 919 (acpid) Tasks: 1 (limit: 4389) Memory: 280.0K CGroup: /system.slice/acpid.service └─919 /usr/sbin/acpid Oct 17 03:53:36 x86-atp-master systemd[1]: Started ACPI event daemon. Oct 17 03:53:36 x86-atp-master acpid[919]: starting up with netlink and the input layer Oct 17 03:53:36 x86-atp-master acpid[919]: 1 rule loaded Oct 17 03:53:36 x86-atp-master acpid[919]: waiting for events: event logging is off
- Verify acpi events are visible in the system, run acpi_listen command and press power button 2-3 times:
$ acpi_listen button/power PBTN 00000080 00000000 button/power LNXPWRBN:00 00000080 00000007 button/power PBTN 00000080 00000000 button/power LNXPWRBN:00 00000080 00000008
NOTE: current power button handler is /etc/acpi/powerbtn-acpi-support.sh, but it does not work for some reason
- Create custom power button event rule:
$ cat > /etc/acpi/events/powerbtn-custom-rule << EOF event=power (PBTN) 00000080 action=/etc/acpi/powerbtn-custom-handler.sh EOF
- Create custom power button event handler and make it executable:
$ cat > /etc/acpi/powerbtn-custom-handler.sh << EOF #!/bin/sh echo "Hello from PBTN!" > /dev/tty1 EOF $ chmod +x /etc/acpi/powerbtn-custom-handler.sh
- Restart acpid service to activate the new functionality:
$ service acpid restart
- Press power button shortly, you should see "Hello from PBTN!" on the main console