Can DMA settings be changed "on the fly" on TMS320C5505?

Todd Anderson78572

During initialization and first interrupt, one buffer size is needed. However, after that, ideally, it would be required to change the buffer size to line up interrupts with incoming data stream.

Can the buffer size for a transmit DMA and receive DMA be changed after the first interrupt?

This would be set up to overcome the errata for I2S "Transmit Path Internal Delays" and DMA "Receive Path Internal Delays."

over 12 years ago

0 Steve Tsang over 12 years ago

TI__Mastermind 23785 points

Are you are referring to the transfer size?

0 Todd Anderson78572 over 12 years ago in reply to Steve Tsang

Guru 14640 points

Yes, transfer size of both the transmit side of DMA and receive side of DMA, and possibly the contents of the transmit buffer as well.

0 Steve Tsang over 12 years ago in reply to Todd Anderson78572

TI__Mastermind 23785 points

The Transfer CVontrol register, source and destination addresses of a channel can be changed after setting the EN = 0. The DMA controller will always complete any on-going burst transfer before stopping channel activity.

Hope this help.

Regards.

0 Todd Anderson78572 over 12 years ago in reply to Steve Tsang

Guru 14640 points

All:

When I get an DMA interrupt, I tried reseting EN to 0, making changes in length and SSAL register for source. When I re-enable EN (inside of ISR), I no longer get interrupts.

However, if I comment out code that resets EN and re-enables EN, I do get interrupts.

BUT, the autoreload needs to be changes, and when I touch the TCR2 register, I no longer get interrupts.

Any ideas of what I am doing wrong? Thanks!

0 Todd Anderson78572 over 12 years ago in reply to Todd Anderson78572

Guru 14640 points

It turns out if you are not in AUTORLD mode, you can then set up the TCR2 register(s), because EN is turned off after the DMA (and subsequent interrupt). So, I have been able to set up for the first interrupt, get the interrupt to be in the "right" spot, and then set up the length and source start address.

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Can DMA settings be changed "on the fly" on TMS320C5505?