New in NRF52 : SPI slave clock out Def as first byte on MISO

[MBarazz]

Hi, 

for my PCB, i'm using an NRF52832 as SPI slave, i send an array of 4 bytes {0xA5,0x00,0x01,ff},  but my SPI master receives always a byte (0xff) before 0xA5.

this ff byte corresponds to DEF byte, but i don't understand why its sent always before my frame ?! 

The SPI master clock freq = 4 MHz 

and i use the same main of sdk v11 spis example.

[Martin Lesund]

Hi Mohcine,

Have you checked the lines with a logic analyser, to see what is going on? (please provide this)

Also, could you provide the settings for your slave? (mode etc.)

 

Best Regards,

Martin L.

[MBarazz]

Thank you for replying to my question.

Blue : CS / Yellow : MISO

as you see, my master is reading 3 bytes (SOF) -> cs is low to receive 3 firt bytes, normally it should be (0xA50001), but finally my nrf spi slave clock out (0xffA500)

My SPI slave settings : 

* MISO_PIN : 16

* MOSI_PIN : 15

* SCK_PIN : 17

* CS_PIN : 23

----------------

Mode : Mode_0

DEF : 0xFF

ORC : 0xFF

[Martin Lesund]

Hi Mohcine, 

I think this can be related to nRF52_PAN_109_add_v1.1.pdf, which have a workaround incorporated in SDK v13. (workaround in chapter 3.9 in included .pdf)

 

Do you have to use SDK v11? (if so, try adding a dummy first byte to SPIS transmit data)

If not, could you try that same example from SDK v15 and see if the problem consist?