void us_ticker_set_interrupt(timestamp_t timestamp)
{
/* We get here absolute interrupt time which takes into account counter overflow.
* Since we use additional count-down timer to generate interrupt we need to calculate
* load value based on time-stamp.
*/
const uint32_t now_ticks = us_ticker_read();
uint32_t delta_ticks =
timestamp >= now_ticks ? timestamp - now_ticks : (uint32_t)((uint64_t) timestamp + 0xFFFFFFFF - now_ticks);
if (delta_ticks == 0) {
/* The requested delay is less than the minimum resolution of this counter. */
delta_ticks = 1;
}
us_ticker_int_counter = (uint32_t)(delta_ticks >> 16);
us_ticker_int_remainder = (uint16_t)(0xFFFF & delta_ticks);
TPM_StopTimer(TPM2);
TPM2->CNT = 0;
if (us_ticker_int_counter > 0) {
TPM2->MOD = 0xFFFF;
us_ticker_int_counter--;
} else {
TPM2->MOD = us_ticker_int_remainder;
us_ticker_int_remainder = 0;
}
/* Clear the count and set match value */
TPM_ClearStatusFlags(TPM2, kTPM_TimeOverflowFlag);
TPM_EnableInterrupts(TPM2, kTPM_TimeOverflowInterruptEnable);
TPM_StartTimer(TPM2, kTPM_SystemClock);
}
/************************************************************************************
*************************************************************************************
* Public functions
*************************************************************************************
************************************************************************************/
void StackTimer_Init(void (*cb)(void))
{
IRQn_Type irqId;
#if FSL_FEATURE_SOC_FTM_COUNT
FTM_Type *ftmBaseAddr = (FTM_Type*)mFtmBase[gStackTimerInstance_c];
FTM_Init(ftmBaseAddr, &mFtmConfig);
FTM_StopTimer(ftmBaseAddr);
ftmBaseAddr->MOD = 0xFFFF;
/* Configure channel to Software compare; output pin not used */
FTM_SetupOutputCompare(ftmBaseAddr, (ftm_chnl_t)gStackTimerChannel_c, kFTM_NoOutputSignal, 0x01);
/* Install ISR */
irqId = mFtmIrqId[gStackTimerInstance_c];
FTM_EnableInterrupts(ftmBaseAddr, kFTM_TimeOverflowInterruptEnable | (1 << gStackTimerChannel_c));
#else
TPM_Type *tpmBaseAddr = (TPM_Type*)mTpmBase[gStackTimerInstance_c];
TPM_Init(tpmBaseAddr, &mTpmConfig);
TPM_StopTimer(tpmBaseAddr);
/* Set the timer to be in free-running mode */
tpmBaseAddr->MOD = 0xFFFF;
/* Configure channel to Software compare; output pin not used */
TPM_SetupOutputCompare(tpmBaseAddr, (tpm_chnl_t)gStackTimerChannel_c, kTPM_NoOutputSignal, 0x01);
/* Install ISR */
irqId = mTpmIrqId[gStackTimerInstance_c];
TPM_EnableInterrupts(tpmBaseAddr, kTPM_TimeOverflowInterruptEnable | (1 << gStackTimerChannel_c));
#endif
/* Overwrite old ISR */
OSA_InstallIntHandler(irqId, cb);
/* set interrupt priority */
NVIC_SetPriority(irqId, gStackTimer_IsrPrio_c >> (8 - __NVIC_PRIO_BITS));
NVIC_ClearPendingIRQ(irqId);
NVIC_EnableIRQ(irqId);
}
/*!
* @brief Main function
*/
int main(void)
{
tpm_config_t tpmInfo;
tpm_chnl_pwm_signal_param_t tpmParam;
tpm_pwm_level_select_t pwmLevel = kTPM_LowTrue;
/* Configure tpm params with frequency 24kHZ */
tpmParam.chnlNumber = (tpm_chnl_t)BOARD_TPM_CHANNEL;
tpmParam.level = pwmLevel;
tpmParam.dutyCyclePercent = updatedDutycycle;
/* Board pin, clock, debug console init */
BOARD_InitPins();
BOARD_BootClockRUN();
BOARD_InitDebugConsole();
/* Select the clock source for the TPM counter as kCLOCK_PllFllSelClk */
CLOCK_SetTpmClock(1U);
/* Print a note to terminal */
PRINTF("\r\nTPM example to output center-aligned PWM signal\r\n");
PRINTF("\r\nYou will see a change in LED brightness if an LED is connected to the TPM pin");
PRINTF("\r\nIf no LED is connected to the TPM pin, then probe the signal using an oscilloscope");
TPM_GetDefaultConfig(&tpmInfo);
/* Initialize TPM module */
TPM_Init(BOARD_TPM_BASEADDR, &tpmInfo);
TPM_SetupPwm(BOARD_TPM_BASEADDR, &tpmParam, 1U, kTPM_CenterAlignedPwm, 24000U, TPM_SOURCE_CLOCK);
/* Enable channel interrupt flag.*/
TPM_EnableInterrupts(BOARD_TPM_BASEADDR, TPM_CHANNEL_INTERRUPT_ENABLE);
/* Enable at the NVIC */
EnableIRQ(TPM_INTERRUPT_NUMBER);
TPM_StartTimer(BOARD_TPM_BASEADDR, kTPM_SystemClock);
while (1)
{
/* Use interrupt to update the PWM dutycycle */
if (true == tpmIsrFlag)
{
/* Disable interrupt to retain current dutycycle for a few seconds */
TPM_DisableInterrupts(BOARD_TPM_BASEADDR, TPM_CHANNEL_INTERRUPT_ENABLE);
tpmIsrFlag = false;
/* Disable channel output before updating the dutycycle */
TPM_UpdateChnlEdgeLevelSelect(BOARD_TPM_BASEADDR, (tpm_chnl_t)BOARD_TPM_CHANNEL, 0U);
/* Update PWM duty cycle */
TPM_UpdatePwmDutycycle(BOARD_TPM_BASEADDR, (tpm_chnl_t)BOARD_TPM_CHANNEL, kTPM_CenterAlignedPwm,
updatedDutycycle);
/* Start channel output with updated dutycycle */
TPM_UpdateChnlEdgeLevelSelect(BOARD_TPM_BASEADDR, (tpm_chnl_t)BOARD_TPM_CHANNEL, pwmLevel);
/* Delay to view the updated PWM dutycycle */
delay();
/* Enable interrupt flag to update PWM dutycycle */
TPM_EnableInterrupts(BOARD_TPM_BASEADDR, TPM_CHANNEL_INTERRUPT_ENABLE);
}
}
}