Nrf SPI Timing Configurations

[rohit]

Hello sir,

I am a beginner on NRF52840. I am using Nrfx_spim example for interfacing sensor with NRF Board.

I have done some driver about Reg_read and Reg_write. I tried to read the device ID of the sensor through SPI yielding improper results.

Hence I probed on the SPI_SCK line and I found that the duty cycle of SPI_SCK is not proper and also set up and hold times are not proper. 

In my requirement timing of the SPI should be as in the attached image below. 

To be more specific I need to meet the timing requirements as of detailed in the image below.

Presently The waveform what I am observing on probing SPI_SCK is as below.

I am pretty sure that my SPI configurations are not proper, please provide me a pointer where I can do the SPI configurations to meet the timing requirements detailed above.

Expecting your kind help.

Thanks,

Rohit 

[rohit]

Hi,

Since  i am unable to find a function to change sampling rate in nRFX_SPIM code example.suggest me a exmple code in peripheral that can be merged in my original code and used in spi function to change sampling rate.

Thanks,

rohit

[Kenneth]

You misunderstand. The problem here is your logic analyzer that can't handle the SPI data stream, you must set the sample rate to higher in your "Hantek" analyzer.

Best regards,
Kenneth

[rohit]

Hi,

I tested out both that drivers (SPI and SPIM) I am unable to figure out how to meet the requirement as given in below diagram.

can you please share me APIs with configurations which can meet above diagram.

please share the waveforms capture by you to meet above requirement.

a project is quite critical quick help could be highly appreciated.

There is another pin named DCx as seen from data sheet which comes under SPIM interface. I want to work as legacy SPI with MISO MOSI SCLK CS PINS, Hence is SPIM Driver suitable for this.

Thanks,

Rohit

[rohit]

Please reply

Gentle reminder....

[Kenneth]

Hi,

We don't have any information other than what you can find through looking in the spi chapter in product specification, spi driver documentation and the spi example in the sdk. Combining the sources of information you should be able to make the spi work with any device that supports spi serial interface.

It is very rarely that anyone look into the detailed hold, setup, rise and fall times for the various signals you refer to. For instance the values you refer to are for most part minimum values in ns range, and I am sure they are not the cause to your current issues. 

Best regards,
Kenneth