/** Initialize the high frequency ticker
*
*/
void us_ticker_init(void)
{
/* Common for ticker/timer. */
uint32_t busClock;
/* Structure to initialize PIT. */
pit_config_t pitConfig;
PIT_GetDefaultConfig(&pitConfig);
PIT_Init(PIT, &pitConfig);
busClock = CLOCK_GetFreq(kCLOCK_BusClk);
/* Let the timer to count if re-init. */
if (!us_ticker_inited) {
PIT_SetTimerPeriod(PIT, kPIT_Chnl_0, busClock / 1000000 - 1);
PIT_SetTimerPeriod(PIT, kPIT_Chnl_1, 0xFFFFFFFF);
PIT_SetTimerChainMode(PIT, kPIT_Chnl_1, true);
PIT_StartTimer(PIT, kPIT_Chnl_0);
PIT_StartTimer(PIT, kPIT_Chnl_1);
}
/* Configure interrupt generation counters and disable ticker interrupts. */
PIT_StopTimer(PIT, kPIT_Chnl_3);
PIT_StopTimer(PIT, kPIT_Chnl_2);
PIT_SetTimerPeriod(PIT, kPIT_Chnl_2, busClock / 1000000 - 1);
PIT_SetTimerChainMode(PIT, kPIT_Chnl_3, true);
NVIC_SetVector(PIT3_IRQn, (uint32_t) pit_isr);
NVIC_EnableIRQ(PIT3_IRQn);
PIT_DisableInterrupts(PIT, kPIT_Chnl_3, kPIT_TimerInterruptEnable);
us_ticker_inited = true;
}
void us_ticker_disable_interrupt(void)
{
PIT_DisableInterrupts(PIT, kPIT_Chnl_3, kPIT_TimerInterruptEnable);
}
