void pwmout_init(pwmout_t* obj, PinName pin)
{
PWMName pwm = (PWMName)pinmap_peripheral(pin, PinMap_PWM);
MBED_ASSERT(pwm != (PWMName)NC);
obj->pwm_name = pwm;
uint32_t pwm_base_clock;
/* Set the TPM clock source to be IRC 48M */
CLOCK_SetTpmClock(1U);
pwm_base_clock = CLOCK_GetFreq(kCLOCK_McgIrc48MClk);
float clkval = (float)pwm_base_clock / 1000000.0f;
uint32_t clkdiv = 0;
while (clkval > 1) {
clkdiv++;
clkval /= 2.0f;
if (clkdiv == 7) {
break;
}
}
pwm_clock_mhz = clkval;
uint32_t channel = pwm & 0xF;
uint32_t instance = pwm >> TPM_SHIFT;
tpm_config_t tpmInfo;
TPM_GetDefaultConfig(&tpmInfo);
tpmInfo.prescale = (tpm_clock_prescale_t)clkdiv;
/* Initialize TPM module */
TPM_Init(tpm_addrs[instance], &tpmInfo);
tpm_chnl_pwm_signal_param_t config = {
.chnlNumber = (tpm_chnl_t)channel,
.level = kTPM_HighTrue,
.dutyCyclePercent = 0,
};
// default to 20ms: standard for servos, and fine for e.g. brightness control
TPM_SetupPwm(tpm_addrs[instance], &config, 1, kTPM_EdgeAlignedPwm, 50, pwm_base_clock);
TPM_StartTimer(tpm_addrs[instance], kTPM_SystemClock);
// Wire pinout
pinmap_pinout(pin, PinMap_PWM);
}
void pwmout_free(pwmout_t* obj)
{
TPM_Deinit(tpm_addrs[obj->pwm_name >> TPM_SHIFT]);
}
/*!
* @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);
}
}
}
