Regarding SPI

[Alan Ajit]

Dear nordic,

I need a advise from your side. my custom board has two spi device both are working same line. one is SD card interface and other is sensor which works in DMA(also i use softdevice in my application).

i have some question regarding this.

1. How i enable DMA in spi which example i refer?

2.if i enable DMA. Is it makes any problem in working of SD card?

3. I want to receive around 150 bytes from host spi using DMA. how i transfer this byte can you help me how i achieve this using DMA.

                                             1. which macros i enabled?

                                             2. what function i use to transfer byte through DMA?

                                             3. is this event handler triggered after completion of DMA transfer?

[haakonsh]

1. You need to see the nrfx SPI Master Example of SDK15.3. 
2. DMA with SPI just means that the transfer is non-blocking with respect to the CPU. There should be no difference as seen from the SD Card.
3. Yes, the event handler set up by the SPIM driver will be called after an SPI transfer has been completed and the received data has been moved to RAM. 

 
 

[Alan Ajit]

Thanks for your replay. I see the example but i am little bit confusing.

1. I want to enable SPI DMA. I think for enabling DMA SPIX_USE_EASY_DMA set to 1 is it right?

2. if I enable this which API i used to transfer the data through spi?

as per above example i didn't see SPIX_USE_EASY_DMA  not set but i see NRFX_SPIM_EXTENDED_ENABLED is enabled. Is this both are same?

3. From your replay you said the event is triggered when full byte transfer complete.is it right?

i need your help i want to know which API used to DMA tranfer ?

[haakonsh]

1. Yes. NRFX_SPIM_EXTENDED_ENABLED  is only used for D/CX functionality.

2. nrfx_spim_xfer

3. You will get an event when all bytes has been transferred and all received bytes are present in RAM.

[liuluan1984]

thank you, I will check