Revision as of 09:56, 11 September 2014

The Radxa Rock has 3 LEDs on board.

LED	GPIO ref.	GPIO number
Green	GPIO0_B4	172
Blue	GPIO0_B6	174
Red	GPIO0_B7	175

All are programmable using either LEDs class devices or GPIOs.

LEDs as class devices

On the latest kernel images (Ubuntu 14.04 server/desktop), the 3 LEDs are configured as LED class devices.

You can control them via /sys/class/leds/

Read the documentation for more information: https://www.kernel.org/doc/Documentation/leds/leds-class.txt

The default status of the three on board leds are:

Red: On when there is power
Green: Flash twice per second after the kernel booting, it's called heartbeat.
Blue: Flash when the uSD card is reading/writing.

You can change the behaviour of each LED by using the echo command on their trigger property.

   root@radxa:~ # echo none > /sys/class/leds/red/trigger
   root@radxa:~ # echo default-on > /sys/class/leds/red/trigger
   root@radxa:~ # echo timer > /sys/class/leds/red/trigger
   root@radxa:~ # echo heartbeat > /sys/class/leds/red/trigger

You can use cat on the trigger property to list all the available values.

   root@radxa:~ # cat /sys/class/leds/red/trigger
   none test_ac-online test_battery-charging-or-full test_battery-charging test_battery-full test_battery-charging-blink-full-solid mmc0 mmc1 timer [heartbeat] backlight gpio default-on sleep rfkill0

Here is the list of current triggers:

none
test_ac-online
test_battery-charging-or-full
test_battery-charging
test_battery-full
test_battery-charging-blink-full-solid
mmc0
mmc1
timer
heartbeat
backlight
gpio
default-on
sleep
rfkill0

LEDs as GPIOs

On the previous kernel images, the LEDs can be controlled as GPIOs.

Below is program in different languages to flash the green led on RR.

C

#include <stdio.h>

int main()
{
FILE *fp = fopen("/sys/class/gpio/export", "w");
if( !fp )
{
printf("error open export file");
return 1;
}
fprintf(fp, "%d", 172);
fclose(fp);

fp = fopen("/sys/class/gpio/gpio175/direction", "w");

if( !fp )
{
printf("error open export file");
return 1;
}
fprintf(fp, "%s", "out");
fclose(fp);

fp = fopen("/sys/class/gpio/gpio175/value", "w");

if( !fp )
{
printf("error open export file");
return 1;
}
fprintf(fp, "%d", 1);

}

Python

import time

def initpin(pinnum, mode):
'''
pinnum: pin number, eg. 172, 175 etc.
mode: pin mode, valid values: in or out
'''
with open('/sys/class/gpio/export', 'w') as f:
f.write(str(pinnum))

with open('/sys/class/gpio/gpio' + str(pinnum) + '/direction', 'w') as f:
f.write(str(mode))

def setpin(pinnum, value):

with open('/sys/class/gpio/gpio' + str(pinnum) + '/value', 'w') as f:
f.write(str(value))

if __name__ == '__main__':
initpin(172, 'out')
while True:
setpin(172, 0)
time.sleep(1)
setpin(172, 1)
time.sleep(1)

Shell

#!/bin/sh

# enable the gpio 172 -> green led
echo 172 > /sys/class/gpio/export

# set the direction to output
echo "out" > /sys/class/gpio/gpio172/direction
while true;
do
echo 0 > /sys/class/gpio/gpio172/value #led on
sleep 1
echo 1 > /sys/class/gpio/gpio172/value #led off
sleep 1
done

@@ Line 1: / Line 1: @@
-The RR has 3 LEDs: green(172), blue(174), red(175).
+The Radxa Rock has 3  LEDs on board.
-All can be programmable.
+{| class="wikitable" style="width:25%; white-space:nowrap; text-align:center"
+! scope="col" | LED
+! scope="col" | GPIO ref.
+! scope="col" | GPIO number
+|-
+! scope="row" | <span style="color: green;">Green</span>
+| GPIO0_B4 || 172
+|-
+! scope="row" | <span style="color: blue;">Blue</span>
+| GPIO0_B6 || 174
+|-
+! scope="row" | <span style="color: red;">Red</span>
+| GPIO0_B7 || 175
+|}
+All are programmable using either LEDs class devices or GPIOs.
 __TOC__
@@ Line 14: / Line 29: @@
 The default status of the three on board leds are:
-    RED: On when there is power
+* <span style="color: red;">Red</span>: On when there is power
-    GREEN: Flash twice per second after the kernel booting, it's called heartbeat.
+* <span style="color: green;">Green</span>: Flash twice per second after the kernel booting, it's called heartbeat.
-    BLUE: Flash when the uSD card is reading/writing.
+* <span style="color: blue;">Blue</span>: Flash when the uSD card is reading/writing.
+You can change the behaviour of each LED by using the '''echo''' command on their '''trigger''' property.
+    root@radxa:~ # echo none > /sys/class/leds/red/trigger
+    root@radxa:~ # echo default-on > /sys/class/leds/red/trigger
+    root@radxa:~ # echo timer > /sys/class/leds/red/trigger
+    root@radxa:~ # echo heartbeat > /sys/class/leds/red/trigger
+You can use '''cat''' on the '''trigger''' property to list all the available values.
+    root@radxa:~ # cat /sys/class/leds/red/trigger
+    none test_ac-online test_battery-charging-or-full test_battery-charging test_battery-full test_battery-charging-blink-full-solid mmc0 mmc1 timer [heartbeat] backlight gpio default-on sleep rfkill0
+Here is the list of current triggers:
+* none
+* test_ac-online
+* test_battery-charging-or-full
+* test_battery-charging
+* test_battery-full
+* test_battery-charging-blink-full-solid
+* mmc0
+* mmc1
+* timer
+* heartbeat
+* backlight
+* gpio
+* default-on
+* sleep
+* rfkill0
 = LEDs as GPIOs =
-On the previous kernel images, the LEDs can be controled as GPIOs.
+On the previous kernel images, the LEDs can be controlled as GPIOs.
 Below is program in different languages to flash the green led on RR.

Difference between revisions of "Rock/LED"

Revision as of 09:56, 11 September 2014

Contents

LEDs as class devices

LEDs as GPIOs

C

Python

Shell