TMS320F28375D: Regarding SFO function

Hi Takahashi,

naoki takahashi said:

I read the status of SFO () and returned 2 indicating an error.
What is the cause and the cause is 2? (Temperature, etc.)
Also, what should I do if 2 indicating an error is returned?

Have you created your own software application? If so, would it be possible to test using one of the HRPWM examples within C2000Ware? 

Best Regards,

Marlyn

Yes, I created my own software application.
We sell equipment to multiple end users, but only one end user has the symptom.
It does not occur with the equipment we own.
Therefore, it cannot be tested using one of the HRPWM examples in C2000Ware.
Therefore, I would like to know the cause and remedy for the phenomenon.

Hello,

This might indicate that the hrpwm is not enabled. Is there anyway to check if the hrpwm clock is enabled?

naoki takahashi said:

We sell equipment to multiple end users, but only one end user has the symptom.

Is it the same equipment across all of these users?

Best Regards,

Marlyn

Hello,

I checked the settings.hrpwm clock is enabled.

These users are all the same equipment.

SFO () errors do not occur from power up, but from time to time during operation.

Best regards,
Takahashi

Hi Takahashi,

Are you meeting the minimum frequency of 60MHz? 

It could be that there is a timeout happening if the clock is too slow.

Best Regards,

Marlyn

Hello,

HRPWMCLK is 100MHz.

Best regards,
Takahashi

The library states that a return value of 2 corresponds to a MEP_ScaleFactor which is greater than maximum value of 255. 
 

Is the end user that sees a return value of 2 using the equipment under higher or lower temperatures?

From the SFO appendix:
“The repetition rate at which an SFO function needs to be executed depends on the application's operating environment. As with all digital CMOS devices, temperature and supply voltage variations have an effect on MEP operation. However, in most applications these parameters vary slowly and therefore it is often sufficient to execute the SFO function once every 5 to 10 seconds. If more rapid variations are expected, then execution may have to be performed more frequently to match the application.”

The SFO() might need to be called more or less frequency depending on the variation of temperature.

Best Regards,

Marlyn

The end user is using at the specified temperature.
The SFO function is executed every 1ms.
After working normally, can sfo () return 2 even if it is normal?

For example, the cycle may be too early and sfo () may return 2.

Best regards,
Takahashi

Hi Takahashi, Marlyn is out of office today, you should expect a response tomorrow.  Sorry for the inconvenience and thank you for your patience.

Regards, Joe

Hi Takahashi,

I do think that is possible. Even so though, the HRMSTEP register will maintain the last MEP scale factor value that was less than 256 for auto conversion. The error function is placed in case you want to stop the PWM under this scenario, you could also use the FREE_SOFT bit within the TBCTL register. Not having an accurate MEP scale factor value may cause the HRPWM feature to not perform the way it is expected, but we don't categorize this behavior.

I recommend calling SFO at a different interval, if possible. Typically the frequency in which you need to call the SFO depends on your system's conditions. 

Best Regards,

Marlyn

Is it correct to understand that SFO() may return 2 even within the specified temperature?

Best regards,
Takahashi