TMS320F280049 ECAP OVERFLOW not set in CAP continuous mode though seen on overflowing on debugger

user4565873

Expert 1250 points

Helllo,

I am using the ECAP on cascade of an CMPSS to compute some electrical motor speed.

The measure is working fine but when the motor stops i expected to read an overflow flag and set my speed to 0.

But no overflow flag is raised.

Here s my config:

// continuous mode, wrap around after event 4.

ECAP_setCaptureMode(ECAP1_BASE, ECAP_CONTINUOUS_CAPTURE_MODE, ECAP_EVENT_2);

ECAP_selectECAPInput(ECAP1_BASE,ECAP_INPUT_CMPSS3_CTRIP_LOW);

ECAP_setEventPolarity(ECAP1_BASE, ECAP_EVENT_1, ECAP_EVNT_RISING_EDGE);

ECAP_setEventPolarity(ECAP1_BASE, ECAP_EVENT_2, ECAP_EVNT_RISING_EDGE);

ECAP_enableCounterResetOnEvent(ECAP1_BASE, ECAP_EVENT_1);

ECAP_enableCounterResetOnEvent(ECAP1_BASE, ECAP_EVENT_2);

ECAP_enableLoadCounter(ECAP1_BASE);

ECAP_startCounter(ECAP1_BASE);

ECAP_enableTimeStampCapture(ECAP1_BASE);

I then read the CTROVF bit of the ECFLG register.

I see the raised flag for CEVT1 and CEVT2, but nothing on the CTROVF.

When i look at the Counter , i do see it overflow... (transition from FFFFFFFF to 00000000)

Can you explain what could be the reason i sont see any OVF flag?

Thank you,

PA.

over 7 years ago

0 Frank Ankapong over 7 years ago

TI__Mastermind 28275 points

Hi user,

That's weird. The OVF should definitely always set when the counter wraps around to 0. How are you confirming that the counter goes from 0xFFFFFFFF to 0x00000000?

0 Frank Ankapong over 7 years ago in reply to Frank Ankapong

TI__Mastermind 28275 points

Also need to add that your post has some contradiction to it. Since you are enabling counter reset on event -> ECAP_enableCounterResetOnEvent(), as long as CEVT1 and CEVT2 are happening, the counter will reset so CTROVF will never happen. Since you are seeing CEVT1 and CEVT2 being set, CTROVF not being set is normal.

0 user4565873 over 7 years ago in reply to Frank Ankapong

Expert 1250 points

Exactlyn, you are right

I should precise CEVT1 and CEVT2 "were" set...

They are not set any more (but i didnt clear the flags) as the nevent does not occur any more. (speed is null and hence emf is null...)

Should i clear those flags to get the CTROVF flag?

Should i enable the interrupt from CTROVF?

0 user4565873 over 7 years ago in reply to user4565873

Expert 1250 points

I check the transition from 00000000 to FFFFFFFF with the debugger..

0 Frank Ankapong over 7 years ago in reply to user4565873

TI__Mastermind 28275 points

Ok. This is what i need you to try. In your application code, wait till CEVT1 and CEVT2 are both set. After, clear CEVT1 and CEVT2. If no additional events happen, you should see the counter transition from 0xFFFFFFFF to 0 in the watch window and CTROVF should be set. This takes about 43 secs at 100MHz CPU clock.

0 user4565873 over 7 years ago in reply to Frank Ankapong

Expert 1250 points

Thank you,
I m going to try this flag clearing tomorrow.
Nevertheless, i need a faster timeout than 43s. So if the flag does occur, it s going to be much later than i need.
I thought i could use the Phase counter reload but i m not sure when to reload it..
By a software reload each time i clear one of my CEVT1 and CEVT2 flag, it could delay by one sampling period my speed computation and i have to check if my speed computation is then accurate enough.
By "SYNC_IN" reload , i dont see exactly what input to use beside a PWM SYNCO.. but i get then the same delay...
I need more or less a timeout of some ms... around 4000rpm... and i m sampling at 66µs.

Thank you very much for your support!
PA.

0 Frank Ankapong over 7 years ago in reply to user4565873

TI__Mastermind 28275 points

PA,

Yes, you are on the right track. If you need the time to elapse quicker than 43s, you will need to utilize the phase load. Write the value you need into the CTRPHS register and enable SYNCI with the SYNCI_EN register. When a SYNCI pulse comes in or if you force a sync through SWSYNC, the contents of CTRPHS will be loaded into TSCTR. I believe TSCTR is writable so you could also easily just write to it.

0 Frank Ankapong over 7 years ago in reply to user4565873

TI__Mastermind 28275 points

Hi PA,

Is this working now or do you still have questions?

0 user4565873 over 7 years ago in reply to Frank Ankapong

Expert 1250 points

Thank you, Franck.
I use a software timer finally... because we loose speed computation accuracy when using CTRPHS register.

Thanks again for the support,
PA N.

0 Frank Ankapong over 7 years ago in reply to user4565873

TI__Mastermind 28275 points

Hi PA,

Glad to hear you have everything working! Let us know if you ran into anymore issues.

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TMS320F280049 ECAP OVERFLOW not set in CAP continuous mode though seen on overflowing on debugger