nrf52832 spi (PSEL.SCK) timing

[yanli_1226]

I want to use nrf52832 SPIM， In nRF52832_PS_V1.4 it described that "An SPI master transaction is started by triggering the START task.Following a START task, the SPI master will generate an END event when both ENDRX and ENDTX have been generated." ，then how can I know if one byte has been transmitted (not after all TX_BUF bytes is transmitted，because I want to add gaps between bytes)?

I used the code below(picture left)，and the SPI timing is like the picture right.

      

My question is I want to add gaps between each 8 clock, just like bellow?

[MartinBL]

Hi,

The whole point of EasyDMA and the ability to specify a buffer of a arbitrary length is to be able to transfer the entire buffer without CPU intervention or delays. If you need delays between every single byte, you will have to send 1 byte long buffers one at the time and make your delay in software. 

[yanli_1226]

Thanks.

when I send 1 byte long buffer at a time without delay, the gaps between bytes are 2.2us, I only want the gaps time to be less than 10ns. there is my code bellow, how can I get the gaps between bytes less than 100ns?

 

[yanli_1226]

Now I use NRF_SPIM0->SHORTS in order to cut short the time between bytes, but it still has 1.4us，I need the time to be less than 100ns?

[yanli_1226]

when I use NRF_SPIM0->SHORTS in order to cut short the time between bytes, but it still has 1.4us，I need the time to be less than 100ns?

[MartinBL]

Hi,

Unfortunately the SPI peripheral simply isn't designed to do what you want it to do. Using shorts as you suggest is probably the best way to go, but even then there will be signal propagation delays, etc. and implementing delays less than 100 ns is not possible.