AM13E23019: eCAP - in APWM mode to output a pulse-train using DMA?

Max Luc Balen

Part Number: AM13E23019

Hi Team,

I have a question posing a certain use case:

Can the eCAP, in APWM mode be used to output a pulse-train using DMA?
Such that the shadow compare register (CAP4) is updated from a buffer using DMA every time Counter==Period.

I've read through the TRM on the configurations for ECCTL2 and ECCTL1, which would enable this, but the wording doesn't make it clear if this can be done.

13 days ago

0 Nilabh Anand 12 days ago

TI__Guru 62200 points

Yes, this works. Here's why the TRM reads ambiguous.
Register field: ECCTL2[DMAEVTSEL] (bits 13:12) — this is the field that selects what event pulses the eCAP's internal DMA-request line. The TRM/register header labels its four encodings generically as "Event 1/2/3/4" because that same 2-bit field is shared between Capture mode (where Event1–4 = CEVT1–4, the four sequential capture-edge events) and APWM mode (where the same four encodings mean something completely different). The header text doesn't spell out the APWM-mode meaning, which is exactly the gap you ran into.

0 Max Luc Balen 2 days ago in reply to Nilabh Anand

TI__Intellectual 910 points

Hi Nilabh,

Thanks for clarifying this is possible - could I also ask how in practice this looks?

0 Nilabh Anand 21 hours ago in reply to Max Luc Balen

TI__Guru 62200 points

Hi Max,

Are you asking for implemnation code?

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AM13E23019: eCAP - in APWM mode to output a pulse-train using DMA?