How to use DMA Scatter/Gather?

[liujinhang]

Dear All,

            I want to use  DMA Scatter/Gather function of MPC5444P,but some experiment phenomenon Confused me,the following is my DMA configurations information:

      

Problem phenomenon：when the major loop completed,the value of DMA_0.TCD[18].DLASTSGA.B.DLASTSGA was added to the DMA_0.TCD[18].DADDR.B.DADDR rather than  the contents of TCD_SG1[]  is loaded into the TCD register, then a DMA Destination Bus Error occurred.

 Can anyone tell me how can i do to make the contents of TCD_SG1[] be loaded into the TCD register ?

here is the reference:http://cache.nxp.com/assets/documents/data/en/application-notes/AN4765.pdf?fromsite=zh-Hans 

thanks very much!

[enes]

Hi, we have same problem with scatter-gather method. Can u give more details about how to solve this problem. 

[petervlna]

Hi,

Just align your TCD in memory for 32bytes. Otherwise DMA will load incomplete or incorrect TCD.

PEter

[petervlna · Accepted solution]

Hi,

Do you have you scatter/gather descriptor 32bytes aligned in memory?

This is mandatory.

Peter

[liujinhang]

It maybe the problem,The addresses of TCD_SG0[] and TCD_SG1[] are really not 32bytes aligned in memory . I misunderstood  the meaning of "0-modulo-32-byte",  thank you for your reminding!

but I do not know how to make the scatter/gather descriptor 32bytes aligned  in memory. Can you give me an example?

 thanks very much!

[liujinhang]

hi, Peter 

I did it ,thanks for your reply.

Best Wishes