NCS - Devicetree & nrfx coexistence

[eyalasko]

Hi,

I have an application based on the "peripheral_uart" sample code (nRF52840DK, NCS2.70)

As I use interchangeably the same pins as GPIOs and UARTE1, I use UARTE1 with NRFX drivers:

nrfx_uarte_t uarte1_inst = NRFX_UARTE_INSTANCE(1)

This seems to work well.  Note that UARTE1 is not defined in the default devicetree file (nrf52840dk_nrf52840.dts) so I didn't modify app.overlay

My questions are -

1. What should I do if I want to use NRFX peripherals that ARE defined in the default dts file (specifically - TWIM0 & TWIM1)
   I added the following to prj.cnf

   CONFIG_I2C=y

   CONFIG_I2C_NRFX=y

   CONFIG_NRFX_TWI0=y

   CONFIG_NRFX_TWI1=y

   But I fail to instantiate TWI instance:

       nrfx_twim_t twim_inst = NRFX_TWIM_INSTANCE(0); // Macro expansion error

2. Is there a way to make a 'pure' NRFX project and get rid of all Devicetree references?

Thanks

[Elfving]

Hello Eyelasko,

As I use interchangeably the same pins as GPIOs and UARTE1, I use UARTE1 with NRFX drivers:

So if I understand you correctly, you want to use nrfx because you want to programmatically change when you use the same pins for multiple different peripherals?

I have to say also that creating a pure nrfx project without dts is not recommended. NCS relies on Zephyr, which is heavily dependent on dts. Disabling a few specific peripherals in order to take control with nrfx however is considered fine.

What should I do if I want to use NRFX peripherals that ARE defined in the default dts file (specifically - TWIM0 & TWIM1)

I believe you would have to change the dts to disable these peripherals, so that nrfx can take control of them directly. Ie. something like this:

&i2c0 {
    status = "disabled";
};

&i2c1 {
    status = "disabled";
};

Regards,

Elfving

[eyalasko]

Thanks Elfving  for your reply.

The answer lies in this post -  Turning on TWIM/TWIS without devicetree

in short -

• Add the following to app.overlay
  
  &i2c0 {

      status = "okay";

      compatible = "nordic,nrf-twim"; // this is the secret (apparently)

  };

  
  

  &i2c1 {

      status = "okay";

      compatible = "nordic,nrf-twim";

  };
  
  

• add the following to prj.conf
  
  CONFIG_I2C=y

[Elfving]

Oh, I see.

Glad you found a solution that worked for you, and thanks for sharing it in case anyone else runs into the same problem

Regards,

Elfving