Using I2C on nRF52840 with 2 sensor devices

Question

I want to get sensor data from the Bosch BNO055 and the NXP MPR121 to the nRF52840 (DK, for now) using I2C. I completed the Nordic Connect SDK Fundamentals course, and am trying to adapt Lesson 6 Exercise 1 to be for two sensors; however, if I try to set them up through one port (i2c0), Zephyr doesn't have the appropriate .yaml files for my sensors, and I also don't have an example main script that works with sensors this way. What I'm now trying to do is put one sensor on the i2c0 port, and one on the i2c1 port, using the same formatting as in the Exercise overlay:

&i2c0 {  

    MPR: MPR@5a{
        compatible = "i2c-device";
        status = "okay";
        reg = < 0x5a >;
        label = "MPR";
    };
};

&i2c1 {  

    BNO: BNO@29{
        compatible = "i2c-device";
        status = "okay";
        reg = < 0x29 >;
        label = "BNO";
    };
};

But, when I continue onto my main script, I'm having trouble writing it for both ports. Even starting out with this (see Image), it gives me errors because I can't alter the name of the struct (at least, I think that's what the error means).

What am I doing wrong?
Am I going about this the right way?
Is there an example code that could be created or that I could follow?
How should I alter the Exercise files to work with 2 i2c devices so I can get sensor data from both at the same time?

Thank you so much! Apologies--I'm just starting out still.

khelmutlord · Accepted Answer

Hello, I would recommend adding the Kconfig "CONFIG_SHELL=y" and "CONFIG_I2C_SHELL=y" for your project especially when starting out. It will allow you to directly interact with I2C devices (i.e. scan to make sure addresses are correct, read ID registers). blog.golioth.io/.../ For your devicetree configuration, try something like the following: &i2c0 { compatible = "nordic,nrf-twi"; status = "okay"; pinctrl-0 = <&i2c0_default>; pinctrl-1 = <&i2c0_sleep>; pinctrl-names = "default", "sleep"; i2c_device_0: i2cdev0@ { status = "okay"; compatible = "vnd,i2c-device"; reg = ; }; i2c_device_1: i2cdev1@ { status = "okay"; compatible = "vnd,i2c-device"; reg = ; }; }; Then, to access the devices, you can use: static const struct i2c_dt_spec0 dev0_i2c = I2C_DT_SPEC_GET(DT_NODELABEL(i2c_device_0)); I think the reason you were getting errors was because you weren't grabbing the node label. I checked through Zephyr and the two devices you are using don't have in-tree Zephyr drivers. Not to worry! Here is a guide from a Nordic partner, Golioth, on creating generic SPI device drivers. Of course you are using I2C here but the general concepts are the same. https://blog.golioth.io/how-to-use-generic-spi-devices-with-zephyr/ Also check the Zephyr I2C docs. https://docs.zephyrproject.org/latest/hardware/peripherals/i2c.html Be sure to skim through them. There are a lot of nice helper functions like " i2c_reg_write_byte_dt" that do a lot of the setup for you depending on the operation you're trying to do. Finally, you can refer to the Zephyr examples for I2C device drivers. This can make it a bit easier to see what setup steps you may need to take for your I2C device. For instance: https://github.com/zephyrproject-rtos/zephyr/tree/main/drivers/sensor/bme680 Thanks, Helmut Lord

khelmutlord · Answer

Hello, 
 You are correct. The orthodox way to add a device driver to Zephyr is to create an out-of-tree driver and fill in all of the boilerplate (kconfigs, etc). For early stages of development it is simpler to use the generic I2C device to at least get communicating. You can continue to use the generic device or you could create device tree bindings, relevant Kconfigs, and a driver implementation and upstream it into Zephyr itself. 
 
 Could you share your build log when you run a pristine build? Sometimes errors will persist in devicetree files until a pristine build. 
 
 Also, the data type you use should be "i2c_dt_spec" right now you are treating it as though it were a variable name. There is a typedef for the struct "i2c_dt_spec" so your lines should be: 
 static const struct i2c_dt_spec dev0_i2c... 
 instead of 
 static const struct i2c_dt_spec 0 dev0_i2c... 
 Thanks, 
 Helmut Lord

Using I2C on nRF52840 with 2 sensor devices

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