API Application Example


API Header file

  #ifndef	__KEY_BACK_LIGHT_H__
  #define	__KEY_BACK_LIGHT_H__
  
  #include	<stdint.h>		/* uint??_t */
  #include	<stdbool.h>		/* Bool */
  /***************************************************************************/
  /*	For Key Pad Back Light
  */
  /***************************************************************************/
  //	#define	DEVICE_KEY_BACK_LIGHT_DEBUG_MESSAGE
  
  #define	DEVICE_LED_KEY_BACK_LIGHT	"/sys/class/leds/key_light/brightness"
  
  
  /*	Key Back Light On/Off
  Input
  	true = Key Back Light On
  	false= Key Back Light Off
  Return
  	0	= Ok to control(On/Off)
  	-1	= Input Parameter Error
  	-2	= Fail to Access Device
  	-3	= Fail to Operation
  */
  extern	int	key_back_light(bool Switch/*true=on, false=Off*/);
  
  /*	get Key Back Light state
  Return
  	0	= Ok to read state
  	-1	= Input Parameter Error
  	-2	= Fail to Access Device
  	-3	= Fail to Operation
  
  *pIsOn	: true = Key Back Light is On, false = Key Back Light is Off
  */
  extern	int key_back_light_is_on(bool *pIsOn);
  
  #endif	/* __KEY_BACK_LIGHT_H__ */

API Source File

  #include	<stdio.h>
  #include	<stdint.h>		/* uint??_t */
  #include	<stdbool.h>		/* bool */
  #include	<stdlib.h>		/* strtoul */
  #include	<string.h>		/* for memset */
  #include	<unistd.h>		/* for open/close .. */
  #include	<fcntl.h>		/* for O_RDWR */
  #include	<sys/ioctl.h>	/* for ioctl */
  #include	<sys/fcntl.h>	/* for O_RDWR */
  
  #include	"KeyBackLight.h"
  
  /*	Key Back Light On/Off
  Input
  	true = Key Back Light On
  	false= Key Back Light Off
  Return
  	0	= Opened
  	-1	= Input Parameter Error
  	-2	= Fail to Access Device
  	-3	= Fail to Operation
  */
  int	key_back_light(bool Switch/*true=on, false=Off*/)
  {
  	FILE *	pDeviceFile;
  	char	pString[2] = { 0, 0 };
  	int		StringLength;
  
  	pDeviceFile = fopen ( DEVICE_LED_KEY_BACK_LIGHT, "w+");
  	if ( pDeviceFile == (FILE *)0 )
  	{
  #ifdef	DEVICE_KEY_BACK_LIGHT_DEBUG_MESSAGE
  		printf ( "Failed To Access Key Pad Back Light Device : %s\n", DEVICE_LED_KEY_BACK_LIGHT );
  #endif	/* DEVICE_KEY_BACK_LIGHT_DEBUG_MESSAGE */
  		return	-2;
  	}
  
  	if ( Switch == true )
  	{
  		pString[0] = '1';
  	}
  	else
  	{
  		pString[0] = '0';
  	}
  	StringLength = (int)strlen(pString);
  	if ( fwrite ( pString, StringLength, 1, pDeviceFile ) < 0 )
  	{
  #ifdef	DEVICE_KEY_BACK_LIGHT_DEBUG_MESSAGE
  		printf ( "Failed To Control Key Pad Back Light\n" );
  #endif	/* DEVICE_KEY_BACK_LIGHT_DEBUG_MESSAGE */
  		return	-3;
  	}
  
  	fclose ( pDeviceFile );
  
  	return	0;
  }
  
  
  /*	get Key Back Light state
  Return
  	0	= Opened
  	-1	= Input Parameter Error
  	-2	= Fail to Access Device
  	-3	= Fail to Operation
  
  *pIsOn	: true = Key Back Light is On, false = Key Back Light is Off
  */
  int key_back_light_is_on(bool *pIsOn)
  {
  	FILE *	pDeviceFile;
  	char	pCommand[128] = {0};
  	char	pString[10] = {0};
  	int		Value;
  
  	if ( pIsOn == (bool *)0 )
  	{
  #ifdef	DEVICE_KEY_BACK_LIGHT_DEBUG_MESSAGE
  		printf( "key_back_light_is_on() : Input Parameter Error\n" );
  #endif	/* DEVICE_KEY_BACK_LIGHT_DEBUG_MESSAGE */
  		return	-1;
  	}
  
  	sprintf(pCommand, "cat %s", DEVICE_LED_KEY_BACK_LIGHT);
  	pDeviceFile = popen(pCommand, "r");
  	if ( pDeviceFile == (FILE *)0 )
  	{
  #ifdef	DEVICE_KEY_BACK_LIGHT_DEBUG_MESSAGE
  		printf ( "Failed To Access Key Pad Back Light Device : %s\n", DEVICE_LED_KEY_BACK_LIGHT );
  #endif	/* DEVICE_KEY_BACK_LIGHT_DEBUG_MESSAGE */
  		return	-2;
  	}
  
  	while( fgets (pString, 10, pDeviceFile) );
  	Value = (uint32_t) strtoul( pString, NULL, 10 );
  	fclose (pDeviceFile);
  
  	*pIsOn = ((Value == 0) ? false:true);
  
  	return	0;
  }