ACS ACR89U-A1 User Manual download pdf (Page 113)

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ACR89U-A1 Application Programming Interface

Version 1.00

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Returns:

portBASE_TYPE

pdFAIL will be returned if the reset command could not be sent to the timer command

queue even after xBlockTime ticks had passed. pdPASS will be returned if the

command was successfully sent to the timer command queue. When the command is

actually processed will depend on the priority of the timer service/daemon task

relative to other tasks in the system, although the timers expiry time is relative to

when xTimerReset() is actually called.

Example usage:

/* When a key is pressed, an LCD back-light is switched on. If 5 seconds

pass

without a key being pressed, then the LCD back-light is switched off. In

this case, the timer is a one-shot timer. */

xTimerHandle xBacklightTimer = NULL;

/* The callback function assigned to the one-shot timer. In this case the

parameter is not used. */

void vBacklightTimerCallback( xTimerHandle pxTimer )

{

/* The timer expired, therefore 5 seconds must have passed since a key

was pressed. Switch off the LCD back-light. */

vSetBacklightState( BACKLIGHT_OFF );

}

/* The key press event handler. */

void vKeyPressEventHandler( char cKey )

{

/* Ensure the LCD back-light is on, then reset the timer that is

responsible for turning the back-light off after 5 seconds of

key inactivity. Wait 10 ticks for the command to be successfully sent

if it cannot be sent immediately. */

vSetBacklightState( BACKLIGHT_ON );

if( xTimerReset( xBacklightTimer, 10 ) != pdPASS )

{

/* The reset command was not executed successfully. Take appropriate

action here. */

}

/* Perform the rest of the key processing here. */

}

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ACS ACR89U-A1 User Manual Page 113

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