DMA SCI RX/TX

Davor

Other Parts Discussed in Thread: HALCOGEN, RM48L950

I am just starting to fool around with DMA, need it for SCI. Are there any examples out there for how to send / receive a simple buffer using SCI and DMA? Using Halcogen generated files.

How do I assign SCI rx interrupt to a DMA request line and then to a DMA channel?

Likewise, how do I start a SCI TX DMA transfer?

Any examples would be appreciated. So far I find the manuals confusing on this topic.

over 12 years ago

0 Davor over 12 years ago

Intellectual 715 points

OK, so the DMA Request Map is in the Datasheet document, not in the technical reference manual. Less confusion now.

0 Chuck Davenport over 12 years ago in reply to Davor

TI__Guru 59540 points

Hello Davor,

I've forwarded your post to our Halcogen team so they can be assistance. The will reply soon.

0 Prathap over 12 years ago in reply to Chuck Davenport

TI__Genius 14205 points

Hi Davor,

4572.SCI_DMA.zip

Attached is a simple example is to demonstrate SCI TX DMA functionality.

* Device Targeted ( sys_main.c can be used for other platforms as well).
       - RM48L950 ( Little Endian Device)
* Module Targeted
      - SCI2 ( Compatibility mode of LIN1)
       - DMA
* Two data chucks are transmitted to demonstrate the varying length configuration of DMA data transfer.

Regards
Prathap

0 Agraj Jain over 12 years ago in reply to Prathap

Intellectual 370 points

Hi Prathap,

I wanted to know how to modify the above example to implement SCI RX DMA. Esp the /*Enable SCI TX DMA*/ part.

Thank you,

Agraj

0 Davor over 12 years ago in reply to Agraj Jain

Intellectual 715 points

I started playing with SCI RX DMA today myself. Can't really get it work. :(

I have the control packet setup, dma req assigned, ctrl packet assigned, channel enabled. I then SETINT: RX DMA and RX DMA ALL. Nothing happens as far as I can see.

POssible to get a working RX DMA example?

0 Davor over 12 years ago in reply to Davor

Intellectual 715 points

Correction, I seem to be getting data but dmaRAMREG->WCP[n].CTCOUNT is not giving me anything useful info.

From manual:

CTCOUNT register is only updated after a channel is arbitrated out of the priority queue.

Hmm, if only one channel,means it will never be arbitrated out of the queue?

0 Prathap over 12 years ago in reply to Davor

TI__Genius 14205 points

Hi Davor,

How do you intend to use SCI + DMA? Are you trying to poll the received data? Did you consider using Frame / Block transfer interrupt? Sorry I cannot give you good suggestion unless I get your used case.

0 Davor over 12 years ago in reply to Prathap

Intellectual 715 points

Hi Prathap,

The lenght of the msg varies (lenght info is included in the message).

I have this working now; DMA is first setup to receive 2 bytes and generate interrupt (this gives me the length of the mssage). DMA is then reprogrammed with this info and a second interrupt is generated at the end of the message.

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DMA SCI RX/TX