S32K DMA

[hajianik]

Hi,

Is it possible to do a DMA transfer of the ADC result register on The COCO bit?

Not talking about hardware triggering(PDB or TRGMUX), I'm not there yet. Just start a conversion and use DMA transfer complete or MAJOR LOOP interrupt to move the result . just initialize the DMA_TCR properly and enable DMA transfer in the ADC module, Is this all there is to it?

How do I link the COCO bit with the DMA channel?

Thanks,

Koorosh Hajiani 

[PetrS]

Hi Koorosh,

you can refer to this example https://community.nxp.com/docs/DOC-333054 

BR, Petr

[hajianik]

Hi Petr,

Thanks for your response,

I  looked at your example, just a few questions please:

 In the following statement

DMAMUX->CHCFG[0] |= DMAMUX_CHCFG_SOURCE(40); // ADC0 COCO is the source of the DMA0 channel

There is a spread sheet attached to Reference manual that actually list the slot number as 42 . Do we need to change 40 to 42?

back to back  PDB indicates  TRIGERS  take place back to back?

Sorry this is my first attempt to do DMA in this Micro.

.

Thanks,

Koorosh Hajiani

[PetrS · Accepted solution]

Hi Koorosh,

It depends which MCU version do you have. There was changes in DMA request mapping across MCU revisions. The Excel sheet mentions this too. Thus use

Slot # 40 … for MCU rev 1 (mask 0N77P)

Slot # 42 … for MCU rev 2 (mask 0N47T) or rev2.1 (0N57U)

The back-to-back operation enables the ADC conversions complete to trigger the next PDB channel pre-trigger and trigger output.  In other words, next PDB trigger is started automatically once previous conversion is completed.

BR, Petr

[hajianik]

Hi Petr,

Thanks for the response.

Just one last question,

Why are we assigning the same input to 4 different channels?

for instance if we were doing 4 back to back conversions on 4 different inputs (ADC0_SE12,ADC0_SE13,ADC0_SE14,ADC0_SE15), It would look something like this:

ADC0->SC1[0] = ADC_SC1_ADCH(12); /* Select AD12 (ADC0_SE12) */

ADC0->SC1[1] = ADC_SC1_ADCH(13); /* Select AD13 (ADC0_SE13) */

ADC0->SC1[2] = ADC_SC1_ADCH(14); /* Select AD12 (ADC0_SE14) */

ADC0->SC1[3] = ADC_SC1_ADCH(15); /* Select AD12 (ADC0_SE15) */

Is that correct?

Thanks

[PetrS]

Yes, the same channel was used in the example, but you can select whatever channel.

BR, Petr