AM2732: Synchronisation of ePWMA and ePWMB

Hi Ito,

Thanks for reaching out to e2e.

Can you clarify if there is a waveform issue for the usecase? These two comments conflict, so I am unsure if the problem is in waveforms or only in the CCS.

-

K.Z said:

as the output waveform does not chang

-

K.Z said:

There is no problem with the output waveform

Secondly, it sounds like you are asking if the register settings and values from the screenshots are correct for TBCTR and TBPHS in mcu_plus_sdk_am273x_09_02_00_52\examples\drivers\epwm\epwm_duty_cycle. Is this correct?

Best,

Haley

Hi Alexander,

Thank you for your reply.

There is no problem with the attached waveform, but they are not sure if it will stay synchronised all the time.
What the customer wants to check is the correct register settings to synchronise ePWMA and ePWMB.

If “1” is put in TBPHS, the TBCTR of ePWMB should be set to “1” when the TBCTR of ePWMA is set to “0”.
However, the customer believes that the current setting is incorrect because the output waveform does not change.

-In other words, they dared to change the settings to check if the settings are correct and tried to change the waveform, but failed.

[Question]

Please check if the register settings in the first attached image can be synchronised without problems.

Haley Alexander said:

Secondly, it sounds like you are asking if the register settings and values from the screenshots are correct for TBCTR and TBPHS in mcu_plus_sdk_am273x_09_02_00_52\examples\drivers\epwm\epwm_duty_cycle. Is this correct?

yes.

Best Regards,

Ito

Hi Ito,

Thanks very much clarifying. This will take a bit of time. I will post an update on 4 April.

Best,

Haley

Hi Ito,

The ePWMB TBCTL_PHSEN value looks correct, but can you confirm if the values from the ePWMB screenshot are from before or after running epwm_duty_cycle example? And was epwm_duty_cycle example modified in anyway?

I am asking because the code calls "EPWM_tbSyncDisable()" which will disable the synchronization. (Even if sync-in event occurs the count value will not be reloaded. Link at the end of post.)

If ePWMB ran epwm_duty_cycle without any edits, this may explain the issue, but I still need time to check the other ePWMB items. I can give another update on 9 April.

Thanks,

Haley

https://dev.ti.com/tirex/content/mcu_plus_sdk_am273x_09_02_00_52/docs/api_guide_am273x/group__DRV__EPWM__MODULE.html#ga49bd10727c0dc4329e8bee9dd362f00b

Hi Haley,

Thank you for your reply.

Haley Alexander said:

The ePWMB TBCTL_PHSEN value looks correct, but can you confirm if the values from the ePWMB screenshot are from before or after running epwm_duty_cycle example? And was epwm_duty_cycle example modified in anyway?

ePWMB is the value after  running epwm_duty_cycle example.

Please see the code below for the modifications.

#include <kernel/dpl/DebugP.h>
#include <kernel/dpl/AddrTranslateP.h>
#include <kernel/dpl/SemaphoreP.h>
#include <kernel/dpl/HwiP.h>
#include <kernel/dpl/ClockP.h>
#include <drivers/epwm.h>
#include "ti_drivers_config.h"
#include "ti_drivers_open_close.h"
#include "ti_board_open_close.h"

//Stop the clock with MSS_EPWMCONFG, 
//ePWM settings and add #define to make it work.
#define ADDR_MSS_EPWMCONFIG             (*(volatile uint32_t*)(0x02120090))

/* Global variables and objects */
static HwiP_Object       gEpwmHwiObject_Pwm0;
static HwiP_Object       gEpwmHwiObject_Pwm1;
static SemaphoreP_Object gEpwmSyncSemObject;

/* Function Prototypes */
static void App_epwmIntrISR_Pwm0(void *handle);
static void App_epwmIntrISR_Pwm1(void *handle);
static void App_epwmConfig(void);

/* variable to hold base address of EPWM that is used */
uint32_t gGpioBaseAddr;

uint32_t gEpwmBaseAddr_Pwm0;
uint32_t gEpwmBaseAddr_Pwm1;
uint32_t gEpwmBaseAddr_Pwm2;


void epwm_duty_cycle_main(void *args)
{
    int32_t             status;
    HwiP_Params         hwiPrmsPwm0, hwiPrmsPwm1;

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

    DebugP_log("EPWM Duty Cycle Test Started ...\r\n");
    DebugP_log("Please refer EXAMPLES_DRIVERS_EPWM_DUTY_CYCLE example user \
guide for the test setup to probe EPWM signal. \r\n");
    DebugP_log("App will wait for 60 seconds (using PWM period ISR) ...\r\n");

    /* Get address after translation translate */
    gGpioBaseAddr = (uint32_t) AddrTranslateP_getLocalAddr(GPIO_LED_BASE_ADDR);
    GPIO_setDirMode(gGpioBaseAddr, GPIO_LED_PIN, GPIO_LED_DIR);

    /* Address translate */
    gEpwmBaseAddr_Pwm0 = (uint32_t)AddrTranslateP_getLocalAddr(CONFIG_EPWM0_BASE_ADDR);
    gEpwmBaseAddr_Pwm1 = (uint32_t)AddrTranslateP_getLocalAddr(CONFIG_EPWM1_BASE_ADDR);
    gEpwmBaseAddr_Pwm2 = (uint32_t)AddrTranslateP_getLocalAddr(CONFIG_EPWM2_BASE_ADDR);

    /* Stop all three channels with epwmconfig in MSS_CTRL */
    ADDR_MSS_EPWMCONFIG = 0x00000000;

    /* Configure PWM */
    App_epwmConfig();

    /* START */
    ADDR_MSS_EPWMCONFIG = 0x07000000;

    while(1)
    {
        ;
    }

    EPWM_etIntrDisable(gEpwmBaseAddr_Pwm0);
    EPWM_etIntrClear(gEpwmBaseAddr_Pwm0);
    EPWM_etIntrDisable(gEpwmBaseAddr_Pwm1);
    EPWM_etIntrClear(gEpwmBaseAddr_Pwm1);
    HwiP_destruct(&gEpwmHwiObject_Pwm0);
    HwiP_destruct(&gEpwmHwiObject_Pwm1);
    SemaphoreP_destruct(&gEpwmSyncSemObject);

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

    Board_driversClose();
    Drivers_close();
}

static void App_epwmConfig(void)
{
    /* ePWMA=triggerA */
    /* TBSTS phsen=0 */
    *(volatile uint32_t *)gEpwmBaseAddr_Pwm0      = 0x00018110;
    /* TBPRD */
    *(volatile uint32_t *)(gEpwmBaseAddr_Pwm0+8)  = 0x001F0000;
    /* CMPA */
    *(volatile uint32_t *)(gEpwmBaseAddr_Pwm0+16) = 0x00070000;
    /* AQCTLA + CMPB */
    *(volatile uint32_t *)(gEpwmBaseAddr_Pwm0+20) = 0x0121000F;
    
    /* ePWMB=triggerB */
    *(volatile uint32_t *)gEpwmBaseAddr_Pwm1      = 0x00018104;
    /* TBPRD */
    *(volatile uint32_t *)(gEpwmBaseAddr_Pwm1+8)  = 0x001F0000;
    /* CMPA */
    *(volatile uint32_t *)(gEpwmBaseAddr_Pwm1+16) = 0x00030000;
    /* AQCTLA + CMPB */
    *(volatile uint32_t *)(gEpwmBaseAddr_Pwm1+20) = 0x0121000B;

    /* ePWMC=12.5MHz output */
    *(volatile uint32_t *)gEpwmBaseAddr_Pwm2      = 0x00018000;
    /* TBPRD */
    *(volatile uint32_t *)(gEpwmBaseAddr_Pwm2+8)  = 0x000f0000;
    /* CMPA */
    *(volatile uint32_t *)(gEpwmBaseAddr_Pwm2+16) = 0x00070000;
    /* AQCTLA + CMPB */
    *(volatile uint32_t *)(gEpwmBaseAddr_Pwm2+20) = 0x02240007;
}

Best Regards,

Ito

Hi Haley,

Thank you for your reply.

I will check the information you have given me.

[Question]
Is the phenomenon correct that the TBCTR of ePWMB becomes “1” when the TBCTR of ePWMA is set to 0, even if TBPHS is changed to “1”?

Best Regards,

Ito