Serial Peripheral Interface

[yugeswar]

Hi team,

             I am trying to work on SPI peripheral on the nordic development board nRF52840. How many SPI compatible ICs are present on the board. And how to identify them?

Thanks.

[Karl Ylvisaker]

Hello,

There is no devices on the nRF52840 DK that uses an SPI interface. The closest thing would be the external memory that uses QSPI, but not SPI. 
You can check this directly in the DK Hardware files.

Best regards,
Karl

[yugeswar]

Thank You Karl.

[Karl Ylvisaker]

Hello,

yugeswar said:

However, like You have mentioned that the MCU is connected to external memory via SPI

This is not quite accurate - I said that the MCU is connected to external memory through QSPI, which is not SPI.
If you would like to test the usage of the external memory mounted on the DK you can check out the QSPI example in the SDK.

Best regards,
Karl

[yugeswar]

Thanks for the reply Karl.

I agree that the external memory is connected to MCU through QSPI. But in the nRF52840_DK_User_Guide,

 https://infocenter.nordicsemi.com/pdf/nRF52840_DK_User_Guide_v1.2.pdf , it is mentioned that both SPI and QSPI are connected to the external memory.

If it is so, and if we configure SPI with the external memory GPIO pins, which APIs can I use to read and write data?

Regards,

Yugeswar

[Karl Ylvisaker]

Hello again, Yungeswar

My apologies, it seems that I misunderstood your intentions earlier.

The answer to your question about which API you could use is indeed either the QSPI peripheral API, or the SPIM peripheral API.
If you would like a reference on how to communicate with the external memory you could look at the Fatfs storage SD Card Example.
If I could ask, however, why is it that you would like to use SPI for the transfers to the external memory, when you could be using QSPI?

The pinout/connection to the external memory could also be helpful for you to take a look at, and it is described in the DKs external memory documentation.

Best regards,
Karl

[yugeswar]

Hello Karl,

Thank You for the suggestions. I am a newbie to the SPI communication protocol. Without implementation of data transfer via SPI, I felt understanding QSPI is a little complicated. Hence I have been focussing my queries on SPI alone.

I will check with both the SPIM and QSPI APIs as suggested and also refer to the SD card example.

Thanks again.

[Karl Ylvisaker]

No problem at all - I am happy to help! :) 

While QSPI might be more daunting to familiarize with initially it comes with a lot of advantages when used to interface with external memory.

Please do not hesitate to open another ticket if you should encounter any issues or questions in the future, or if you should have any follow-up questions about the QSPI usage.

Good luck with your development!

Best regards,
Karl

[yugeswar]

Hello Karl,

Now I have ordered an external SPI slave device (EEPROM), as there are no slave devices on board that supports SPI peripheral. Does the APIs given in https://infocenter.nordicsemi.com/index.jsp?topic=%2Fsdk_nrf5_v16.0.0%2Fgroup__nrfx__spi.html&anchor=gaa882c9d38c2a3c714123cc807757d9bb sufficient to interface with the external device? How can I write and read data from the slave device? Kind advice please.

Thanks.