SPIS of nrf52 could not read the data accuracy

[hzhuxin]

I am working with SPIS example ( sdk version 15.3). SPI master send data regulaly. For example, it sent 5ms cs low, but there are only two bytes transferred, the first byte at begin of 5ms, other one at the end. SPIS of nrf52 not read the second one, what can I do with it?

[Edvin]

Hello,

Is the nRF SPI master or slave?

Did you analyze the SPI lines to get the figure in your question, or did you create this based on the observed behavior? 

[hzhuxin]

[Edvin]

hzhuxin said:

SPIS means SPI slave mode

 Hehe, thanks. I know, but I just wanted to check whether you used an nRF as Master as well, or not.

You probably also know that "MOSI" stands for "Master Out Slave In", so it looks like the master doesn't send all the data, only the first and last byte. That is also why I asked you whether you have actually analyzed the lines using an oscilloscope or a logic analyzer, or if you have come to this conclusion based on the behavior of the slave application?

If this is a trace from an oscilloscope or a logic analyzer, then I think you need to find out why the master doesn't send all the data. Does it expect the slave to respond, perhaps? What does your MISO line look like? And what is your SPIM?

[hzhuxin]

The SPIM is another mcu， i couldn't change it's behavior.
In fact, i just want the spis to read the data normally without any bytes lost.

This is almost the same trace from my osilloscope, but i only have two probe, so draw it myself to make it clear reflect the relationship of cs\data\clk and timing.

What i ask is, if master send these data to me, i should received two bytes, am i right?
But in fact, only one bytes could be received.

How can i got the second byte?

[hzhuxin]

“Does it expect the slave to respond, perhaps?What does your MISO line look like?And what is your SPIM?”

No, it not need any response.

MISO is not connected!

SPIM is from another MCU which i coudn't change!