AM263P4: LP-AM263P4: Issue with Complementary PWM Generation

Part Number: AM263P4

Hello,

I am working with the LP-AM263P4 development board and am generating complementary PWM signals using PWM1 and PWM3.

My target configuration is:

• PWM Frequency: 20 kHz
• PWM Period: 50 µs

However, I am not getting the expected output. Initially, the PWM waveform matches the expected behavior, but after some time it changes unexpectedly. This pattern repeats at the same interval every time.

I have attached:

• Output waveform screenshots
• ti_driver_open_close.c source file

My main application code is shown below:

void configAQ(uint32_t base)
{
    EPWM_setActionQualifierAction(
        base,
        EPWM_AQ_OUTPUT_A,
        EPWM_AQ_OUTPUT_HIGH,
        EPWM_AQ_OUTPUT_ON_TIMEBASE_DOWN_CMPA);

    EPWM_setActionQualifierAction(
        base,
        EPWM_AQ_OUTPUT_A,
        EPWM_AQ_OUTPUT_LOW,
        EPWM_AQ_OUTPUT_ON_TIMEBASE_UP_CMPA);
}

void epwm_deadband_main(void *args)
{
    /* Open drivers to open the UART driver for console */
    Drivers_open();
    Board_driversOpen();

    DebugP_log("EPWM DeadBand Test Started ...\r\n");
    DebugP_log("EPWM DeadBand Example runs for 5 Secs \r\n");

    /* Start all the EPWM Timebase Counters */
    SOC_setMultipleEpwmTbClk(gEpwmTbClkSyncDisableMask, TRUE);

    configAQ(CONFIG_EPWM1_BASE_ADDR);
    configAQ(CONFIG_EPWM3_BASE_ADDR);

    uint16_t duty, duty2;
    duty = 40;
    duty2 = 40;

    EPWM_setCounterCompareValue(
        CONFIG_EPWM1_BASE_ADDR,
        EPWM_COUNTER_COMPARE_A,
        (5000 * duty) / 100);

    EPWM_setCounterCompareValue(
        CONFIG_EPWM3_BASE_ADDR,
        EPWM_COUNTER_COMPARE_A,
        (5000 * duty2) / 100);

    while(1);

    ClockP_sleep(5);

    /* Stop all the EPWM Timebase Counters */
    SOC_setMultipleEpwmTbClk(gEpwmTbClkSyncDisableMask, FALSE);

    DebugP_log("EPWM DeadBand Test Passed!!\r\n");
    DebugP_log("All tests have passed!!\r\n");

    Board_driversClose();
    Drivers_close();
}

I would appreciate your help in understanding the following:

1. Why does the PWM waveform change periodically after initially producing the expected output?
2. What could be causing this behavior?
3. Is there any issue with my Action Qualifier configuration or the overall PWM setup?
4. How can I fix this issue to obtain a stable 20 kHz complementary PWM output?

Additionally, I have another question:

• How can I independently control each PWM module (for example, PWM1 and PWM3) instead of operating them only as complementary outputs? I would appreciate any guidance or example demonstrating how to control each PWM separately.

Thank you for your support.
ANBURAJA A

Note:
0 is PWM1 A , 1 is PWM1 B

2 is PWM3 A, 3 is PWM3 B

ti_drivers_config.c ti_drivers_open_close.c