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4.9 GPIO-LED
On a embbeded Linux system, the LEDs are commonly controlled by sysfs interface.
This example demonstrates how to control the LEDs by sysfs with
echo
command
or
led_test
application.
Hardware Preparation:
Hardware debugging environment to see chapter second.
MYD-AM335x series development board
Software Preparation:
Linux Kernel 4.1.18
echo, led_test application
Test Steps:
Copy cross compiled
<WORKDIR>/Examples/led/led_test
to
/usr/bin
directory of the
MYD-AM335x series development board.
View the device node of MYD-AM335X LED devices as below:
# ls /sys/class/leds
myc:green:user1 myd:green:user2 myd:green:user3
Control the MYD-AM335X LED by
echo
command as below:
D3
:
#echo "1" > /sys/class/leds/myc\:green\:user1/brightness
#echo "0" > /sys/class/leds/myc\:green\:user1/brightness
D39
:
#echo "1" > /sys/class/leds/myd\:green\:user2/brightness
#echo "0" > /sys/class/leds/myd\:green\:user2/brightness
D40
:
#echo "1" > /sys/class/leds/myd\:green\:user3/brightness
#echo "0" > /sys/class/leds/myd\:green\:user3/brightness
View the device node of MYD-AM335X-Y LED devices as below:
# ls /sys/class/leds
51