AM2434: Timing and PWM

Cherry Zhou

Part Number: AM2434

Hi Team,

Here's an issue from the customer may need your help:

1) The timer is set and interrupts are turned on, but interrupts cannot be triggered. The program is as follows, is it just required to initialize and TimerP_start(gTimerBaseAddr[TIMER0_WU])?

2) Set PWM interrupt: EPWM_etIntrCfg(epwmBaseAddr, ePWM_et_INTR_EVT_CNT_EQ_ZRO,
EPWM_et_INTR_period_first_EVT); GPIO is asserted when flag==2 is determined in the interrupt service function.

The behavior is not asserted high at the second PWM and the trigger point is not at the point that counts to 0.

(Note: the upper part of the figure is the trigger point, while the lower arrow indicates the actual trigger point)

Could you help check this case? Thanks.

Best Regards,

Cherry

over 2 years ago

0 Sri Vidya Gunturi over 2 years ago

TI__Expert 7586 points

Could you please provide more details?

The timer interrupts are not being triggered?

Cherry Zhou said:
TimerP_start(gTimerBaseAddr[TIMER0_WU])?

Yes you have to start the timer if the time start button is not checked in the syscfg Timer Configuration.

Cherry Zhou said:
EPWM_etIntrCfg(epwmBaseAddr, ePWM_et_INTR_EVT_CNT_EQ_ZRO,
EPWM_et_INTR_period_first_EVT)

Could you please tell how is the EPWM and Timer are interconnected in the configuration? Are those two separate questions?

Cherry Zhou said:
(Note: the upper part of the figure is the trigger point, while the lower arrow indicates the actual trigger point)

I assume the yellow line is the PWM waveform and the blue line is the time when EPWM Interrupt at CTR = 0 is entered.

Regarding the Interrupt being triggered after some time after the CTR = 0 event. This is because the software will have some interrupt latency which is close to 600 nsec to handle and service the actual Application ISR. This 600 nsec is in Release mode.

For more information, please refer below links:

To create interrupt from Timer, refer to the below example:

https://software-dl.ti.com/mcu-plus-sdk/esd/AM263X/latest/exports/docs/api_guide_am263x/EXAMPLES_KERNEL_DPL_INTERRUPT_PRIORITIZATION.html

In this example, you can see 3 timer interrupts with priorities: