/****************************************************************************
*
* NAME: vTickTimerISR
*
* DESCRIPTION Timer interrupt service routine.
*
* Flash LED so we can see software is running.
*
* Check for data ready for transmission and initiate.
*
* PARAMETERS Name RW Usage
* None.
*
* RETURNS:
* None.
*
* NOTES:
* None.
*
*
****************************************************************************/
PUBLIC void vDongleInitTickTimer(void)
{
DBG_vPrintf(DEBUG_DEVICE_CONFIG,"vDongleInitTickTimer\n");
/* Initialise tick timer to give 10ms interrupt */
vAHI_TickTimerConfigure(E_AHI_TICK_TIMER_DISABLE);
vAHI_TickTimerWrite(0);
vAHI_TickTimerInterval(DONGLE_TICK_PERIOD_COUNT);
vAHI_TickTimerIntEnable(TRUE);
vAHI_TickTimerConfigure(E_AHI_TICK_TIMER_RESTART);
}
/****************************************************************************
*
* NAME: SetTickCompare
*
* DESCRIPTION:
* Set the tick timer compare register
*
* RETURNS:
* True if the compare register value is in the future
*
****************************************************************************/
OS_HWCOUNTER_SET_CALLBACK(APP_cbSetTickTimerCompare, u32CompareValue)
{
/* calculations are relative to the last compare register value to account for counter wrap around */
int32 s32NextDelta = u32CompareValue - s_u32LastExpiredTime;
uint32 u32CurDelta = u32AHI_TickTimerRead() - s_u32LastExpiredTime;
/*
* Race condition here. If the tick counter has incremented passed the compare point
* in the time between reading it and loading the compare register the interrupt will be missed.
* Increase the delta to take account of this time. To minimise this time, the number of
* instructions between the register read and write to the interval register should be minimised.
*/
u32CurDelta += 100;
if (s32NextDelta > 0 && u32CurDelta < s32NextDelta)
{
vAHI_TickTimerInterval(u32CompareValue);
s_u32CompareTime = u32CompareValue;
return TRUE;
}
return FALSE;
}
