adding I2C to asset_tracker_v2 in V2.5.0

[Timothy]

I have V2.5.0 asset_tracker_v2 running on a nrf9160DK board. I need to add I2C capability. I tried copying the code from the i2c_api example. I added "CONFIG_I2C=y" to prj.conf. I added the following to the overlay file:

/ {
aliases {
i2c-0 = &i2c0;
};
};

I get the following error when I try to compile the asset_tracker_v2. I have tried changing to i2c-1,i2c-2 and I still get the same error. what am I doing wrong? How do I add I2C capability to asset_tracker_v2 and what pins are the I2C signals (SCL/SDA) available?

In file included from C:/Nordic1/v2.5.0/zephyr/include/zephyr/toolchain.h:50,
from C:/Nordic1/v2.5.0/zephyr/include/zephyr/kernel_includes.h:19,
from C:/Nordic1/v2.5.0/zephyr/include/zephyr/kernel.h:17,
from C:/Nordic1/v2.5.0/zephyr/soc/arm/nordic_nrf/validate_enabled_instances.c:7:
C:/Nordic1/v2.5.0/zephyr/include/zephyr/toolchain/gcc.h:81:36: error: static assertion failed: "Only one of the following peripherals can be enabled: SPI2, SPIM2, SPIS2, TWI2, TWIM2, TWIS2, UARTE2. Check nodes with status \"okay\" in zephyr.dts."
81 | #define BUILD_ASSERT(EXPR, MSG...) _Static_assert(EXPR, "" MSG)
| ^~~~~~~~~~~~~~
C:/Nordic1/v2.5.0/zephyr/soc/arm/nordic_nrf/validate_enabled_instances.c:51:1: note: in expansion of macro 'BUILD_ASSERT'
51 | BUILD_ASSERT(CHECK(2), MSG(2));
| ^~~~~~~~~~~~
[119/466] Building C object zephyr/CMakeFiles/zephyr.dir/subsys/logging/log_core.c.obj
ninja: build stopped: subcommand failed.
FATAL ERROR: command exited with status 1: 'C:\Nordic1\toolchains\c57af46cb7\opt\bin\cmake.EXE' --build 'C:\Nordic1\test_n160\asset_tracker_v2\build'

************zephyr.dts******************

aliases {
led0 = &led0;
led1 = &led1;
led2 = &led2;
led3 = &led3;
pwm-led0 = &pwm_led0;
sw0 = &button0;
sw1 = &button1;
sw2 = &button2;
sw3 = &button3;
bootloader-led0 = &led0;
mcuboot-button0 = &button0;
mcuboot-led0 = &led0;
watchdog0 = &wdt0;
spi-flash0 = &mx25r64;
i2c-0 = &i2c0;
ext-flash = &mx25r64;
};

i2c0: i2c@8000 {
compatible = "nordic,nrf-twim";
#address-cells = < 0x1 >;
#size-cells = < 0x0 >;
reg = < 0x8000 0x1000 >;
clock-frequency = < 0x186a0 >;
interrupts = < 0x8 0x1 >;
status = "disabled";
};
i2c1: i2c@9000 {
compatible = "nordic,nrf-twim";
#address-cells = < 0x1 >;
#size-cells = < 0x0 >;
reg = < 0x9000 0x1000 >;
clock-frequency = < 0x186a0 >;
interrupts = < 0x9 0x1 >;
status = "disabled";
};
i2c2: arduino_i2c: i2c@a000 {
compatible = "nordic,nrf-twim";
#address-cells = < 0x1 >;
#size-cells = < 0x0 >;
reg = < 0xa000 0x1000 >;
clock-frequency = < 0x61a80 >;
interrupts = < 0xa 0x1 >;
status = "okay";
pinctrl-0 = < &i2c2_default >;
pinctrl-1 = < &i2c2_sleep >;
pinctrl-names = "default", "sleep";
pcal6408a: pcal6408a@20 {
compatible = "nxp,pcal6408a";
status = "disabled";
reg = < 0x20 >;
gpio-controller;
#gpio-cells = < 0x2 >;
ngpios = < 0x8 >;
int-gpios = < &gpio0 0x6 0x11 >;
};
};
i2c3: i2c@b000 {
compatible = "nordic,nrf-twim";
#address-cells = < 0x1 >;
#size-cells = < 0x0 >;
reg = < 0xb000 0x1000 >;
clock-frequency = < 0x186a0 >;
interrupts = < 0xb 0x1 >;
status = "disabled";
};

[Naeem Maroof]

Hello

1) The peripheral you want to use should be enabled. I can see that I2c0 and I2c1 both are "disabled" and the i2c2 is enabled.

2) Many instances share the same ID (please refer to the documentation / product specification to see the peripherals having same ID). As such, only one of such peripheral should be enabled. And that is also present in the error you are getting.

So, if you want to use i2c0, the put the following in the overlay: (I am assuming you will not be using i2c1 and i2c2)

/ {
aliases {
    i2c-0 = &i2c0;
    };
};

&i2c0{
    status = "okay";
}
&i2c1{
    status = "disabled";
}
&i2c2{
    status = "disabled";
}

After that, when you compile the code, please go and check the pins used by i2c0. If you want to change the pins then you can do so using the PINCTRL in the overlay.

/BR, Naeem

[Timothy]

Naeem thanks for the quick response. I do not want to change the pin assignments of the I2C ports. I just want to know what they are so I can connect a I2C device. Where do I find the pin assignment for the I2C ports?

[Timothy]

Naeem thanks for the quick response. I do not want to change the pin assignments of the I2C ports. I just want to know what they are so I can connect a I2C device. Where do I find the pin assignment for the I2C ports?

[Naeem Maroof]

Hello,

Please open the compiled output DTS and you will be able to locate the peripheral and the pins.

First click to open the compiled DTS, and then serach for the node. We can see that i2c0 pins are defined using pinctrl.

Next, locate pinctrl in the same file:

pin numbers that are used are defined. You can change the pins using pinctrl in the overlay as well.

You can also see pins for i2c0 from the gui interface:

/BR, Naeem

[Timothy]

Naeem The hardware team has told me I need to use I2C2 on pins 30/31. What do I do in the overlay file to make i2c2 be active with pins 30/31. I notice that there is already an arduino i2c2 defined in the V2.5.0 DTS file.