void us_ticker_free(void)
{
PIT_StopTimer(PIT, kPIT_Chnl_1);
PIT_StopTimer(PIT, kPIT_Chnl_0);
TPM_DisableInterrupts(TPM2, kTPM_TimeOverflowInterruptEnable);
NVIC_DisableIRQ(TPM2_IRQn);
us_ticker_inited = false;
}
void us_ticker_init(void)
{
/* Common for ticker/timer. */
uint32_t busClock;
/* Structure to initialize PIT. */
pit_config_t pitConfig;
if (us_ticker_inited) {
/* calling init again should cancel current interrupt */
TPM_DisableInterrupts(TPM2, kTPM_TimeOverflowInterruptEnable);
return;
}
PIT_GetDefaultConfig(&pitConfig);
PIT_Init(PIT, &pitConfig);
busClock = CLOCK_GetFreq(kCLOCK_BusClk);
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. */
tpm_config_t tpmConfig;
TPM_GetDefaultConfig(&tpmConfig);
/* Set to Div 32 to get 1MHz clock source for TPM */
tpmConfig.prescale = kTPM_Prescale_Divide_32;
TPM_Init(TPM2, &tpmConfig);
NVIC_SetVector(TPM2_IRQn, (uint32_t)tpm_isr);
NVIC_EnableIRQ(TPM2_IRQn);
us_ticker_inited = true;
}
/*!
* @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);
}
}
}
void us_ticker_disable_interrupt(void)
{
TPM_DisableInterrupts(TPM2, kTPM_TimeOverflowInterruptEnable);
}
