RE: Custom board I2C, device_is_ready() failing with init_res == 5

tedhavelka — Tue, 18 Jan 2022 06:27:42 GMT

Hello again Devzone,

In an unusual turn I have found the root cause soon after posting here, of our Zephyr based firmware on custom board returning *sensor->state->initialized = true, and *sensor->state->init_res = 5. While I created most of the required custom board DTS and Kconfig files, I missed [custom_board_name].yaml. Poor mistake on my part. I also did not see direct mention of this .yaml file or its purpose in the general Device Tree how-to readings, nor Kconfig tutorials and explanatory notes.

The custom board .yaml file contains the following:

identifier: custom-board-name
name: Custom-Board-Name-Non-Secure
type: mcu
arch: arm
toolchain:
- gnuarmemb
- zephyr
ram: 128
flash: 256
supported:
- i2c

The first two stanzas are all that I modified. These appear to be free-form strings. The last line caught my eye, as it was the I2C device which it felt like Zephyr was reporting to have a general I/O error. Somehow it looks like `supported: - i2c` is necessary in this .yaml file in addition to the app's prj.conf file which includes the line `CONFIG_I2C=y`.

One thing that is strange, the RAM and FLASH sizes here are smaller than what's specified in Nordic nRF9160 documentation. Those docs say that the application processor, an ARM Cortex-M33 has 256kB static RAM and 1024kB program flash. I wonder why these differ?

It is okay for Nordic Semi engineers to close this ticket. Our firmware is largely ported to a custom board with this fix.

- Ted