topic PRINTF floats in MCUXpresso IDE

PRINTF floats

rudycoppens — Wed, 04 Jul 2018 15:43:27 GMT

Hello,

I am using the following hard and software:

- NXP MKE14F512

- Segger J-Link Edu

- MCUXpresso 10.1.1_606

- FREERTOS

I readed the following page to do this:

MCUXpresso SDK API Reference Manual: Debug Console

To init the debug console I use:

BOARD_InitDebugConsole();

From the link above I tried running the following line of code:

PRINTF("Execution timer: %s\n\rTime: %u ticks %2.5f milliseconds\n\rDONE\n\r", "1 day", 86400, 86.4);

You would expect to see 85.4 milliseconds in the print console but I only get spaces.

See attached file.

Re: PRINTF floats

BlackNight — Wed, 04 Jul 2018 16:42:16 GMT

Depending on your library used, printf() for floating point is not turned on as this usually adds a lot of code overhead.

I assume you are using newlib-nano?

So you have to turn this on in the linker settings:

With this I get:

Time: 86400 ticks 86.40000 milliseconds

I hope this helps,

Erich

PS: there is a background article (with more points about using the GNU libraries) available here: printf() and scanf() with GNU ARM Libraries | MCU on Eclipse

Re: PRINTF floats

lpcxpresso_supp — Thu, 05 Jul 2018 07:02:39 GMT

Just to add to Erich comment, if you are using the (default) Redlib library then integer only printf's are enabled by default - using the symbol CR_INTEGER_PRINTF (in the Preprocessor settings for your project). Remove this to get floating point printf's

For more information see section 15.5, "Use of printf" in the MCUXpresso IDE v10.2 User Guide for more details.

Regards,

MCUXpresso IDE Support

Re: PRINTF floats

rudycoppens — Thu, 05 Jul 2018 08:05:04 GMT

Thanks!

I did not change any of these settings, I was using Redlib (semihost-nf).

It is now working with the solution of Erich Styger. I could not find the folder where the Redlib library is located.

Regards,

Rudy