nrf91 how to use twi(i2c)?

[john.liu]

ncs v1.9.1

Reference nrf\applications\serial_lte_modem\src\twi

This example does not see how to configure the pin.so how to config SCK and SDA Pin?

Thanks!!!

[john.liu]

  Reference zephyr.dts

  

  i2c0: i2c@8000 {

                compatible = "nordic,nrf-twim";

                #address-cells = < 0x1 >;

                #size-cells = < 0x0 >;

                reg = < 0x8000 0x1000 >;

                clock-frequency = < 0x186a0 >;

                interrupts = < 0x8 0x1 >;

                status = "disabled";

                label = "I2C_0";

            };

But no define SCK and SDA pin.

[Sigurd Hellesvik]

Hi

You can add them yourself, using the syntax seen in zephyr.dts for i2c2:

            i2c2: arduino_i2c: i2c@a000 {
                compatible = "nordic,nrf-twim";
                #address-cells = < 0x1 >;
                #size-cells = < 0x0 >;
                reg = < 0xa000 0x1000 >;
                clock-frequency = < 0x186a0 >;
                interrupts = < 0xa 0x1 >;
                status = "disabled";
                label = "I2C_2";
                sda-pin = < 0x1e >;
                scl-pin = < 0x1f >;

Regards,
Sigurd Hellesvik

[john.liu]

thank you.I wank to know i2c0,i2c1...which pin is used and why can't it be found.

[john.liu]

It seems that the i2c of this is not used. Is there any other examples I can refer to.(Examples that seem easier to understand.)

[Sigurd Hellesvik]

Hi

You can set the pins for i2c0 and/or i2c1 by using Devicetree overlays.
Here is an example for an overlay file setting the pins for one of the i2c devices:

&i2c1 {
    status = "okay";
    sda-pin = < 12 >;
    scl-pin = < 13 >;
};

Regards,
Sigurd Hellesvik

[john.liu]

Thank you very much!!! I now understand how it works.I have one more question.

config SLM_TWI
	bool "Access TWI interface with SLM AT command"
	select I2C
	default y if "$(dt_nodelabel_enabled,i2c0)" || \
		     "$(dt_nodelabel_enabled,i2c1)" || \
		     "$(dt_nodelabel_enabled,i2c2)" || \
		     "$(dt_nodelabel_enabled,i2c3)"

How to enable "dt_nodelabel_enabled,i2c0 ".I didn't find a reference.

[Sigurd Hellesvik]

See zephyr/scripts/kconfig/kconfigfunctions.py#L124-L136.

You enable it by setting the "okay" as from my last post.

    status = "okay";

Regards,
Sigurd Hellesvik

[john.liu]

thank you.

I tried the following.

Either i2c0 or i2c1 is enabled but i2c2 is enabled.Am I still wrong somewhere?

[john.liu]

Hi Sigurd Hellesvik:

This is the project I built, and it seems that I2C is not working after running.

https://github.com/JohnLiu-cloud/nrf91_i2c

[Sigurd Hellesvik]

Hi

The overlay file will not be added just because you have it in the same folder.

See Set devicetree overlays for how to set it.

Regards,
Sigurd Hellesvik