How to read/get SPI csn pin logical level ?

[Romain]

Hi all,

I am using a nRF52840-DK as SPI slave with a MSP430 as host SPI master for a nRF8001 replacement application.

As I am absolutely not familiar with high level functions (threading, etc.) used within zephyr\samples\bluetooth\hci_spi\, I would start with a simple simulation of nRF8001 behaviour.

Thus I want to manage NREQ (CSN) and NRDY lines.

I set SPI slave driver through prj.conf

# Common SPI driver
CONFIG_SPI=y                            # SPI hardware bus
CONFIG_SPI_SLAVE=y                      # SPI slave support [EXP]
#CONFIG_SPI_ASYNC=y                     # to use later...

# Zephyr SPI driver
#CONFIG_SPI_2=y
#CONFIG_SPI_2_OP_MODES=2

# Nordic SPI driver
CONFIG_NRFX_SPIS=y                      # Not needed here as overlay specifies compatible = "nordic,nrf-spis" ?
CONFIG_NRFX_SPIS2=y                     # Not needed here as overlay specifies compatible = "nordic,nrf-spis" ?

and overlay

&spi2 {
    compatible = "nordic,nrf-spis"; 
    #address-cells = <1>;
    #size-cells = <0>;
    reg = <0x40023000 0x1000>;
    interrupts = <35 1>;                /* correspond to peripheral ID (PS 4.2.4) */
    status = "okay";
    label = "SPI_2";
    sck-pin = <36>;
    mosi-pin = <37>;
    miso-pin = <38>;
    csn-pin = <35>;                    /* depend on SPIS */
    def-char = <0xff>;                 /* depend on SPIS */
};

At this point I want to read NREQ (CSN) logical level to set NRDY active (low) and call spi_transceive().

I tried gpio_pin_get(dev_spi, 35) but it returns invalid parameters error since dev_spi is not a gpio instance, I guess.

I read that there is no way to get event when CSN goes low here ...

If the above is still true, what would be the simplest configuration to catch CSN event ?

If there is no way, can I use the SPI driver interrupt ? How this information "interrupts = <35 1>" should be used ?

Thank you.

Development setup:

• Windows 10
• nRF Connect SDK 1.4.0
• SES V5.10d
• PCA10056

[Didrik Rokhaug]

Hi,

Have you considered moving the BLE host layer to the MSP430, and just running the BLE controller on the nRF52?

That would let you use one of the hci_<transport> samples on the nRF52 without any modifications to the sample.

Depending on the availabel libraries etc. on the MSP430, that might be easier than to emulate the behavior of the nRF8001.

Best regards,

Didrik

[Romain]

Hi Didrik,

I assume there is no simple answer to my questions above and will evaluate

Didrik Rokhaug said:

moving the BLE host layer to the MSP430

About driver interrupt (here SPI with id 35): is this id intended to be referred in the code or it just appears within dts files for building ?

Thank you.

Best regards,

Romain

[Didrik Rokhaug]

Romain said:

About driver interrupt (here SPI with id 35): is this id intended to be referred in the code or it just appears within dts files for building ?

 The interrupts field is already set in the .dtsi file for the SoC, so you do not need to set it in your overlay file.

The field is used by the driver to know which interrupt to use for the peripheral, but it is not something you need to use yourself.