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chaining DMA question ( Linkport, SDRAM)

Question asked by bombardiero on Nov 8, 2011
Latest reply on Nov 9, 2011 by jeyanthi.jegadeesan

Hi, I would like to  continously recieve data from external device (ExtCLK 25 MHz ) using link port  on EZ-KIT ADSP21161N  to internal memory ( unsigned int buffer[1000];)


DSP has 100MHz clock. After recieved 1000 datas I move them to SDRAM also using chaining dma.

I am not sure about this

ADSP-21161 datasheet , Managing DMA Channel Priority

"Because more than one DMA channel can make a DMA request in a particular

cycle, the I/O processor prioritizes DMA channel service. DMA

channel prioritization determines which channel can use the IOD (I/O

Data) bus to access memory"


DMA_External will start moving data from internal  to external memory after DMA_linkport completes (4000 DSP ticks) (so i will loose data  during SDRAM writing(?))  or between  next recieved Linkport data?


And what will happen if i start reading from buffer[1000] when Linport is writing it (who will use IOD)?


How many cycles is between appear interrupt and its service ( I can find it in datasheet,where shoud i look?)