Stuck with DMA between a FIFO in a UDB and memory

[AlFr_4739666]

What I'm trying to do is to transfer 80 bytes from a buffer to a FIFO. It kind of works, but not right. I'm using bursts of 4 bytes and a setting to have a DREQ on every burst. So I set the size of 80 and burst size of 4.

CyDmaChSetConfiguration(dmaCh,4, 1, 0,0,0); // avf 4 per burst, req every time

CyDmaTdSetConfiguration(dmaTd, X_BYTES , dmaTd, DMA__TD_TERMOUT_EN | TD_INC_SRC_ADR);

So it loops to the same Td.

My custom UDB gets triggered by a hardware signal every 30 usec and starts sending requests when the FIFO is empty. The DMA sends the data and I get an interrupt on NRQ after (what looks on the scope as) 20 bursts, that is 80 bytes as it should.  I change the pointer to the start of the new buffer to wait for the next trigger event. But I can see that the number of bytes sent is not always 80, so the data is being sent from wrong addresses.  It's possible that my UDB has a bug. If so I'll find it, Verilog is not a problem. The question is it possible that the misalignment happens elsewhere  and more importantly how can I make sure a new set of data will start from the right place?  In another thread I have seen an advice to disable, release and enable again the DMA channel. But will that not hit performance? Is there a way to just reset the address? Also am I right to chain the td to itself or should it be terminated and a new one started after one full set of 80 bytes?

Thanks.

[AlFr_4739666]

OK, have to reply myself. Setting DMA_DISABLE_TD and then doing

  CyDmaChSetInitialTd(dmaCh, dmaTd);

  CyDmaChEnable(dmaCh, 1);

before the next block helped. Next question: PSoC5 doesn't seem to have the "DMA channel" primitive to edit. How can I set up the DMA to transfer 16 bits at a time? Both to F0 and F1 in a single cycle?

[NoriTan · Accepted solution]

There are several kinds of 16-bit register window concatenating two 8-bit registers as follows.

The register address is declared in the cyfitter.h file like following.

You can use the register declaration in your API functions.

Regards,

Noriaki