How to print floating numbers with nRF Connect SDK?

RE: How to print floating numbers with nRF Connect SDK?

Jørgen Holmefjord — Tue, 20 Sep 2022 20:16:26 GMT

Which version of nRF Connect SDK are you using?

NEWLIB_LIBC_FLOAT_PRINTF depends on CONFIG_NEWLIB_LIBC, have you set this to "y" as well in your prj.conf file?

RE: How to print floating numbers with nRF Connect SDK?

NeelSun — Fri, 16 Sep 2022 19:35:29 GMT

I'm unable to print float values as well and I get the following error when I try to add CONFIG_NEWLIB_LIBC_FLOAT_PRINTF=y in my prj.conf file.

' y' is not a valid value for the bool symbol NEWLIB_LIBC_FLOAT_PRINTF (defined at lib/libc/Kconfig:101). Assignment ignored.

What could be the reason?

RE: How to print floating numbers with nRF Connect SDK?

hmahdi — Fri, 21 Jan 2022 13:16:47 GMT

I had a similar issue. Not sure why, but it just won't print floats. I solved it by converting to char and printing that instead:

char buf[MAX];
gcvt( THE_FLOAT, 6, buf);//need to import stdio.h
printk("%s",buf);

RE: How to print floating numbers with nRF Connect SDK?

Jørgen Holmefjord — Mon, 01 Mar 2021 14:15:45 GMT

bojan, I think what awneil meant was that "Segger Debug Terminal" only shows logs/prints from RTT interface, while the printf function is normally redirected to the UART serial terminal.

If nothing is printed at all, this does not sound like an issue with printing floats, but rather how you read the logs/prints in general.

I tried adding your printf-line to the BLE UART peripheral sample in NCS v1.4.2, and it prints the float over UART without any added Kconfigs:

float tmp = 123.456;
printf("Floating number: %3.2f\n", tmp);

Output in serial terminal:

*** Booting Zephyr OS build v2.4.0-ncs2  ***
Floating number: 123.46
Starting Nordic UART service example

RE: How to print floating numbers with nRF Connect SDK?

bojan — Sat, 27 Feb 2021 10:22:31 GMT

Hey, awneil.

Thanks for your reply. Unfortunately, I don't get floating number printed with

printf("Floating number: %3.2f\n", tmp);

even on RTT.

RE: How to print floating numbers with nRF Connect SDK?

awneil — Sat, 27 Feb 2021 09:53:11 GMT

[quote userid="76830" url="~/f/nordic-q-a/72130/how-to-print-floating-numbers-with-nrf-connect-sdk"]Nothing is printed in my Segger Debug Terminal[/quote]

I think that only does RTT ?