question on devicetree (nrf52840dongle)


Kristoff Bonne
 

Hi all,


I have been experimenting with running zephyr on some nrf52840dongle device that I bought some time ago.


According the document on this device, zephyr should support both i2c and spi on these devices, and as the nrf52840 a pinmux it should be possible to use any pin for this.
Looking at the devicetree file (*) it says that i2c uses pins 26 and 27 for i2c0, and 30 and 31 for i2c1, which is a bit strange as of these 4 pins, the dongle only exposes ports 26 and 30. (No idea why the person who created this dts-file chose those pins).



Question:

- How exactly does the devicetree on zephyr work?
Can I assume that if I would modify the dts file compile it and 'link' that dto-file in the compilation address, I would be able to use other pins?

- Am I correct to assume that the device-tree file actually instructs some part of the boot-process to configure the pinmux in a certain way? (so it's not just a reflection of the configuration of the pinmux 'as it', but it a configuration that is pushed to the pinmux)

- Where can I find information on how to actually do this?




(*) boards/arm/nrf52840dongle_nrf52840/nrf52840dongle_nrf52840.dts


Thanks in advance for any help!


Kr.

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