device driver API

[ntn888]

i just have a quick basic question about the device driver API, why does the samples/drivers/i2c_fujitsu_fram application not use a device tree node for the i2c peripheral? (with the <reg> address set to the i2c chip address and so on) i've seen explanations in the docs where these sensors on the i2c bus being defined as a child node. what is the difference?

[Einarh]

Hello!

The sample you are referring to is using Zephyr's Devicetree API to access the I2C peripheral, which is the recommended method for accessing peripherals in Zephyr.

In the application the device is defined like this:

#define I2C_DEV DT_LABEL(DT_ALIAS(i2c_0))

~~~~

const struct device *i2c_dev;

i2c_dev = device_get_binding(I2C_DEV);

This code finds hardware specifications in the board specific devicetree file, and saves them in a device struct which is then used to access the device in the application.

Putting the hardware specifications in a devicetree file makes your code more portable, because you can compile your application for a different board just by changing the devicetree overlay, while using the same application code.

You ca read more about Zephyr's devicetree here:

https://docs.zephyrproject.org/latest/guides/dts/intro.html

http://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/zephyr/reference/devicetree/api.html

Hope this helps, best regards,

Einar