Kinetis Software Development Kit中的主题 Re: Printing Floating point values to fsl_debug_console FRDM-K64F

Printing Floating point values to fsl_debug_console FRDM-K64F

michaellyons — Thu, 12 Mar 2015 21:02:15 GMT

Hello,

I'm using KDS 2.0, KDSK1.1.0, PEx, with the FRDM-K64F. I'd like to print the Floating point accelerometer values to the terminal using fsl_debug_console. Strings and integers print fine but it seems debug_printf() doesn't support float. I also tried

sprintf(str,"%f");

printf("%s",str);

but everything except the floating point val would print. Is there a compiler setting that must be changed to support floating point printing?

Thanks,

Michael

Re: Printing Floating point values to fsl_debug_console FRDM-K64F

likeli — Fri, 13 Mar 2015 02:43:32 GMT

Hello Michael,

To print floating point values, you need to enable float/double support to printf() function. In KDS, please look under: Properties->C/C++ Build->Settings->Tool Settings->Cross ARM C Linker, then add

-u _printf_float to the linker options. It will be OK.

For example, you can write code like this:

float temp=36.5;

printf("\r\n temp=%f \n\r",temp);

Re: Printing Floating point values to fsl_debug_console FRDM-K64F

michaellyons — Tue, 17 Mar 2015 16:05:19 GMT

That worked! Thank you.

Re: Printing Floating point values to fsl_debug_console FRDM-K64F

dave408 — Thu, 19 Mar 2015 14:43:50 GMT

I tried adding -u _printf_float to my linker settings for my application, but it didn't work:

Can you please tell me if I've missed something? Thanks!

Re: Printing Floating point values to fsl_debug_console FRDM-K64F

michaellyons — Thu, 19 Mar 2015 14:55:00 GMT

Hi Dave,

I went to Properties->C/C++ Build->Settings->Cross ARM C Compiler->Miscellaneous then in the "Other compiler flags" box I added "-u_printf_float". That seemed to work for me. Are you using KDS, KSDK, and PEx with the FRDM-K64F?

Thanks,

Michael

Re: Printing Floating point values to fsl_debug_console FRDM-K64F

dave408 — Thu, 19 Mar 2015 14:57:36 GMT

Ok, thanks! That's totally not what Ke had said. :smileyhappy: He specifically mentioned the linker, but hey it didn't work and you got it working, so I'll try your suggestion. Thank you!

Re: Printing Floating point values to fsl_debug_console FRDM-K64F

dave408 — Thu, 19 Mar 2015 15:00:07 GMT

This is so odd. Setting the compiler flags didn't work for me, either. I'm using KDS 2.0, KSDK 1.1, and MQX. I am not using processor expert. This is with a K64F. I just found a post by Erich Styger, so I'll check that out now. Thank you for your prompt reply!

Re: Printing Floating point values to fsl_debug_console FRDM-K64F

michaellyons — Thu, 19 Mar 2015 15:04:00 GMT

Okay, I haven't tried this with MQX yet so that might be the difference. Screenshot below for help.

If you find the answer please post here.

Re: Printing Floating point values to fsl_debug_console FRDM-K64F

dave408 — Thu, 19 Mar 2015 15:06:22 GMT

Ok, I'll definitely post my findings if anyone else presents a solution elsewhere. Erich's post mentions linker settings as well, not compiler settings. It also has a lot of detail that I'm not comfortable with, and since it mentioned PEx and not KSDK, I'm not sure it's the right direction for me. I'll keep digging, and if I can't find the answer, I'll post up a new thread and link to it here. Thanks!

Re: Printing Floating point values to fsl_debug_console FRDM-K64F

matthias — Fri, 20 Mar 2015 07:46:39 GMT

Hello Dave,

I had a similar problem, so maybe this solution helps: printf() with float values

Regards,

Matthias

Re: Printing Floating point values to fsl_debug_console FRDM-K64F

dave408 — Fri, 20 Mar 2015 13:10:28 GMT

Hi Matthias, thank you *so* much for posting a link to your thread! That was absolutely the problem, and now printf is able to display fp values. Thanks!!!