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LEDs can be turned on and off by writing an appropriate value to the brightness file under the LED class directory. A value between 0 and 255 can be written to the brightness file.

Writing any value apart from 0 to the brightness file turns the LED on. As the Armadillo-400 Series LEDs do not have brightness control functionality, the value has no effective meaning.

[armadillo ~]# echo 1 > /sys/class/leds/yellow/brightness

Writing 0 to the brightness file turns the LED off.

[armadillo ~]# echo 0 > /sys/class/leds/yellow/brightness

The current state of the LED can be obtained by reading the brightness file. 0 represents the off state, and any other value represents an on state.

[armadillo ~]# cat /sys/class/leds/yellow/brightness
0

A trigger to turn the LED on and off can be set by writing an appropriate value to the trigger file under the LED class directory. For values supported by the trigger file, refer to 表9.1「LEDs and LED Class Directories」.

Executing the commands below will cause LED3 to repeatedly turn on for 1 second and then off for 500 milliseconds.

[armadillo ~]# echo timer > /sys/class/leds/red/trigger
[armadillo ~]# echo 1000 > /sys/class/leds/red/delay_on
[armadillo ~]# echo 500 > /sys/class/leds/red/delay_off

The current trigger of the LED can be obtained by reading the trigger file. The value enclosed in [] is the current trigger.

[armadillo ~]# cat /sys/class/leds/yellow/trigger
[none] mmc0 timer heartbeat default-on

The I/O direction can be changed by writing an appropriate value to the direction file under the GPIO class directory. For values supported by the direction file, refer to 表9.4「direction Configuration」.

The input level can be obtained by reading the value file under the GPIO class directory. 0 represents a LOW level and 1 a HIGH level. The input level can be obtained both when the I/O direction is set to INPUT and OUTPUT.

[armadillo ~]# cat /sys/devices/virtual/gpio/CON9_1/value
0

The input level can be set by writing an appropriate value to the value file under the GPIO class directory. 0 represents a LOW level and 1 a HIGH level. Input level configuration can only be carried out when the I/O direction is set to OUTPUT.

[armadillo ~]# echo 1 > /sys/devices/virtual/gpio/CON9_2/value

The time format used as an argument to the date command is: MMDDhhmmCCYY.ss. In the example below, the date and time are set to 1/23/2000 4:56:00.

[armadillo ~]#date Displays the current system clock
[armadillo ~]#date 012304562000.00
[armadillo ~]#date
Check that the system clock was set correctly
      

The system clock can be set using the NTP client. For more information, refer to 「NTP Client」.

[armadillo ~]#hwclock Displays the hardware clock
[armadillo ~]#hwclock --utc --systohc Sets hardware clock in UTC
[armadillo ~]#hwclock
Check that the hardware clock was set correctly