Hi,

After searching the internet I found out that when using CONFIG_NEWLIB_LIBC=y I also have to add CONFIG_NEWLIB_LIBC_FLOAT_PRINTF=y to make things work as expected.

There are multiple "backends" for the [s]printf function in the Zephyr:

* minimal libc (cbprintf)
* newlib

In case of newlib, you need to enable CONFIG_NEWLIB_LIBC_FLOAT_PRINTF as you mentioned above.
In case of the minimal libc (cbprintf), you need to set CONFIG_CBPRINTF_FP_SUPPORT.

Please note that the newlib is not a prerequisite for making printf work with floats.

Where can I find this kind of information, e.g. dependencies, to avoid having to search the internet for answers in the future?

Usually, Kconfig is a good source of information for such dependencies (e.g. search for "float printf" in the menuconfig).

There is also a more comprehensive documentation about the formatted output support in general (though, it does not mention the newlib-related details):
https://docs.zephyrproject.org/latest/reference/misc/formatted_output.html

Regards,

Stephanos

-----Original Message-----
From: users@... <users@...> On Behalf Of Anders via lists.zephyrproject.org
Sent: Wednesday, November 24, 2021 6:24 PM
To: users@...
Subject: [Zephyr-users] Configuration?

Hi,

I have just started working with Zephyr and struggled the other day with getting sprintf working for floats.

After searching the internet I found out that when using CONFIG_NEWLIB_LIBC=y I also have to add CONFIG_NEWLIB_LIBC_FLOAT_PRINTF=y to make things work as expected.

Where can I find this kind of information, e.g. dependencies, to avoid having to search the internet for answers in the future?

Thx in advance,
Anders