NRF52832 DMA HALF TRANSFER INTERRUPT AND EASYDMA ARRAYLIST

Question

Hi , 
 1-) Is there any dma half transfer interrupt ? if there is where it is in documents ? ( i check this link but i couldnt see anything about this https://infocenter.nordicsemi.com/index.jsp?topic=%2Fcom.nordic.infocenter.nrf52832.ps.v1.1%2Feasydma.html 
 2-) How is that ArrayList organised by EasyDma? 
 Lets assume that i am reading 32bytes from spi to ram . i have prepared 2 array with 16bytes in size. So how is it organized by dma ; 
 - 1,3,5,7,9... byte will go 1st array and 2,4,6,8... to second array ? 
 -OR 1-16th Bytes will be stored in 1st array and 17-32th will be in second array ? 
 - or what ? 
 Thank you all. 
 
 Best regards.

haakonsh · Accepted Answer

I updated my previous post before I noticed that you had answered, I suggest you read it. 1) The Maximum buffer size is 255 bytes, therefore I suggest 32 x 128bytes (4096bytes), or 17 x 241(4097bytes). 
 2) Since the list feature auto-increment the DMA address pointer, we can immediately start another transfer. DMA is handled by the SPIM HW automatically. 
 3) Correct, this will keep track of how many arrays have been filled. The "fork" is a feature of a PPI — Programmable peripheral interconnect channel where one EVENT can trigger one additional TASK without having to create an additional channel. 
 4)You can set up another compare event. By setting the CC[1] register to half of CC0, and enabling the interrupt for CC1 by writing to the INTENSET register. The TIMER driver should forward an event to the application's TIMER callback after half the arrays have been transferred. The callback is provided as the event handler in nrfx_timer_init .

MCB · Answer

haakonsh said: Yes. The Array List feature is fairly simple, the pointer register in f.ex. the SPIM: RXD.PTR , is incremented by the RXD.MAXCNT size after the EVENTS_END has been fired. It is then up to you to trigger another TASKS_START in order to fill the next array of RXD.MAXCNT size. 
 i read whole Saadc section in document but i couldnt see such specification. i have also tested it by real code. But RESULT.PTR did not changed after END event .Is there any specific bit to activate auto increment of xxx.PTR ? 
 
 Sorry , does this auto increment of xxx.PTR behavior belong to only some peripherals such as spi ? or any peripheral with EasyDma?

NRF52832 DMA HALF TRANSFER INTERRUPT AND EASYDMA ARRAYLIST

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