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Difference between revisions of "Rock/LED"

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{{rock_header}}
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{{Languages| rock/LED}}
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The Radxa Rock has 3  LEDs on board.
 
The Radxa Rock has 3  LEDs on board.
  
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__TOC__
 
__TOC__
  
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= LEDs as class devices =
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== LEDs as class devices ==
  
 
On the latest kernel images (Ubuntu 14.04 server/desktop), the 3 LEDs are configured as LED class devices.
 
On the latest kernel images (Ubuntu 14.04 server/desktop), the 3 LEDs are configured as LED class devices.
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* rfkill0
 
* rfkill0
  
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= LEDs as GPIOs =
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'''The GPIO control external LEDs is moved to [[rock/GPIO|GPIO]] page.'''
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On the previous kernel images, the LEDs can be controlled as GPIOs.
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Below is program in different languages to flash the green led on RR.
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== C ==
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<syntaxhighlight lang="c" enclose="div">
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#include <stdio.h>
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int main()
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{
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  FILE *fp = fopen("/sys/class/gpio/export", "w");
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  if( !fp )
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  {
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    printf("error open export file");
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    return 1;
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  }
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  fprintf(fp, "%d", 172);
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  fclose(fp);
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  fp = fopen("/sys/class/gpio/gpio175/direction", "w");
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  if( !fp )
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  {
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    printf("error open export file");
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    return 1;
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  }
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  fprintf(fp, "%s", "out");
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  fclose(fp);
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  fp = fopen("/sys/class/gpio/gpio175/value", "w");
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  if( !fp )
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  {
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    printf("error open export file");
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    return 1;
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  }
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  fprintf(fp, "%d", 1);
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}
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</syntaxhighlight>
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== Python ==
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<syntaxhighlight lang="python" enclose="div">
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import time
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def initpin(pinnum, mode):
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  '''
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  pinnum: pin number, eg. 172, 175 etc.
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  mode: pin mode, valid values: in or out
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  '''
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  with open('/sys/class/gpio/export', 'w') as f:
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    f.write(str(pinnum))
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  with open('/sys/class/gpio/gpio' + str(pinnum) + '/direction', 'w') as f:
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    f.write(str(mode))
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def setpin(pinnum, value):
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  with open('/sys/class/gpio/gpio' + str(pinnum) + '/value', 'w') as f:
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    f.write(str(value))
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if __name__ == '__main__':
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  initpin(172, 'out')
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  while True:
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    setpin(172, 0)
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    time.sleep(1)
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    setpin(172, 1)
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    time.sleep(1)
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</syntaxhighlight>
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== Shell ==
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== turn off LEDs ==
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<syntaxhighlight lang="bash" enclose="div">
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#!/bin/sh
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use "none" trigger for triggered LEDs or just turn off for non-triggered LEDs.
  
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# enable the gpio 172 -> green led
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e.g.
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echo 172 > /sys/class/gpio/export
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# set the direction to output
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    echo none > /sys/class/leds/blue/trigger
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echo "out" > /sys/class/gpio/gpio172/direction
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    echo none > /sys/class/leds/green/trigger
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while true;
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    echo 0 > /sys/class/leds/red/brightness
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do
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echo 0 > /sys/class/gpio/gpio172/value #led on
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sleep 1
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echo 1 > /sys/class/gpio/gpio172/value #led off
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sleep 1
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done
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</syntaxhighlight>
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you can modify [https://github.com/radxa/linux-rockchip/blob/889bc07b6e62705a8ea04b021db3cc73a786c2d4/arch/arm/mach-rk3188/board-rk3188-box.c#L1330 kernel] to change default state at boot.

Latest revision as of 05:23, 6 January 2015

English
中文（中国大陆）‎
español
Deutsch
português do Brasil

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

The GPIO control external LEDs is moved to GPIO page.

turn off LEDs

use "none" trigger for triggered LEDs or just turn off for non-triggered LEDs.

e.g. 

   echo none > /sys/class/leds/blue/trigger
   echo none > /sys/class/leds/green/trigger
   echo 0 > /sys/class/leds/red/brightness

you can modify kernel to change default state at boot.

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