TMS320F28075: SDFM Sinc3 with two incorrect samples

Jordan Zhou

Part Number: TMS320F28075

Hi,

Do we have any walkaround for Sinc3 filter, two incorrect samples?

Customer want's to use Sinc3, with interrupt only on the third sample. There are some CPU resources to do, but no CLA. CLA is totally used for other tasks.

Thanks a lot.

Br, Jordan

over 5 years ago

0 Manoj Santha Mohan over 5 years ago

TI__Guru 55700 points

Jordon,

Are you using SDSYNC event? If so, we don't have a clean way to avoid first two incorrect samples on SDSYNC event from SDFM module.

There is however a way to get around this using either PWM (or) timer to interrupt SDFM to read the SDFM filter results. Most of our customers don't use SDFM data acknowledge interrupt, instead they use PWM (or) a timer interrupt which triggers only after atleast latency of sinc filter + 5 SD-Cx cycles after a SDSYNC event to read SDFM filter results. This way they can avoid two incorrect samples and can precisely time when they want to read SDFM filter results.

Regards,

Manoj

0 Jordan Zhou over 5 years ago in reply to Manoj Santha Mohan

TI__Genius 10180 points

Manoj,

You are right, we are thinking the same way to do it. But just one doubt: is it stable, from other customer's experience?

I mean that, the time cost for AMC130x + Sinc3, is it fixed? +5 cycles, where does it come from, other customers?

Thanks a lot.

Br, Jordan

0 Manoj Santha Mohan over 5 years ago in reply to Jordan Zhou

TI__Guru 55700 points

Jordan,

Yes, it is stable and is tested to work properly.

Time cost = Latency of Sinc filter + 5 SD-Cx cycles is the confirmation we received from SDFM designer based on simulation results. We need additional 5 SD-Cx period for SDFM data filter results to get updated.

Regards,

Manoj

0 Jordan Zhou over 5 years ago in reply to Manoj Santha Mohan

TI__Genius 10180 points

Thanks Manoj.

Br, Jordan

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TMS320F28075: SDFM Sinc3 with two incorrect samples