How to redirect printf to UART when using Segger Embedded Studio

RE: How to redirect printf to UART when using Segger Embedded Studio

AndreasF — Wed, 20 Feb 2019 14:36:55 GMT

Hi.

[quote user="northernLight"]

Thankyou for your time on this.

I believe these only configure NRF_LOG instructions, not direct printf commands

When using NRF_LOG_INFO commands with RTT set and UART unset I get data to the debug terminal in SES

But with the same code with RTT unset and UART set I get no output to my serial monitor window

[/quote]

This is not what happend with the sdk_config.h file I gave you?

[quote user="northernLight"]What is the function of retarget.c? Does it affect the destination for standard output?[/quote]

It is an implementation of functions in stdio.h.

[quote user="northernLight"]How do I incorporate flash_placement.xml in the compiler configuration?[/quote]

Follow step 7 on this guide.

Best regards,

Andreas

RE: How to redirect printf to UART when using Segger Embedded Studio

northernLight — Wed, 20 Feb 2019 10:36:28 GMT

Andreas

Thankyou for your time on this.

I believe these only configure NRF_LOG instructions, not direct printf commands

When using NRF_LOG_INFO commands with RTT set and UART unset I get data to the debug terminal in SES

But with the same code with RTT unset and UART set I get no output to my serial monitor window

:-(

What is the function of retarget.c? Does it affect the destination for standard output?

I am using the sdk_config for the peripheral/uart example from SDK 12.3. I'll try the file you propose.

How do I incorporate flash_placement.xml in the compiler configuration?

Many thanks

Rob

RE: How to redirect printf to UART when using Segger Embedded Studio

AndreasF — Wed, 20 Feb 2019 10:05:13 GMT

Hi Rob.

The startup files are code which are run before main starts, you can call it a bootstrapping of the system, so you are correct in that they are "in effect the boot file".

[quote user="northernLight"][/quote]

As a recap of the problem I am trying to solve: I would like to redirect printf (or stop its current redirection) so that the compiled code operates without Segger Studio, just with a UART connection

Does stdio.h define the standard output destination for putchar()?

I don't think you should have to add anything to the code, you should only need the correct configuration in sdk_config.h and include the file retarget.c.

Can you try with my configuration: devzone.nordicsemi.com/.../sdk_5F00_config.h

I think the vital thing is that you have defined this as 1:

// <e> NRF_LOG_BACKEND_SERIAL_USES_UART - If enabled data is printed over UART
//==========================================================
#ifndef NRF_LOG_BACKEND_SERIAL_USES_UART
#define NRF_LOG_BACKEND_SERIAL_USES_UART 1
#endif

And this as 0:

// <e> NRF_LOG_BACKEND_SERIAL_USES_RTT - If enabled data is printed using RTT
//==========================================================
#ifndef NRF_LOG_BACKEND_SERIAL_USES_RTT
#define NRF_LOG_BACKEND_SERIAL_USES_RTT 0
#endif

As you can see here from the configuration wizard:

Hope this works for you.

Best regards,

Andreas

RE: How to redirect printf to UART when using Segger Embedded Studio

northernLight — Wed, 20 Feb 2019 09:21:19 GMT

As a recap of the problem I am trying to solve: I would like to redirect printf (or stop its current redirection) so that the compiled code operates without Segger Studio, just with a UART connection

Does stdio.h define the standard output destination for putchar()?

Rob

RE: How to redirect printf to UART when using Segger Embedded Studio

northernLight — Wed, 20 Feb 2019 09:12:59 GMT

As a check I reverted to the original files and the build completed

Thanks again for helping with this.

For my education what is the broad purpose of these start-up files? They seem to be the first instructions that the processor executes on power-up.

Are they in effect the boot file?

Rob

RE: How to redirect printf to UART when using Segger Embedded Studio

northernLight — Wed, 20 Feb 2019 09:06:51 GMT

Andreas,

Many thanks. I am unsure what to do with the flash_placement.xml.

I included the *.s files in the build and excluded the old ones:

But I get the following build errors:

Building ‘twi_master_using_app_twi_pca10028_sdk12’ from solution ‘twi_master_using_app_twi_pca10028_sdk12’ in configuration ‘nrf51422_xxac’
1> Assembling ‘ses_nrf51_startup.s’
2> Assembling ‘thumb_crt0.s’
1> Linking twi_master_using_app_twi_pca10028_sdk12.elf
1>
1> Diagnostics:
1> remark: increasing alignment of section .vectors from 1 to 2 because it contains executable instructions
1> error: undefined symbol: __SEGGER_init_copy
1> error: undefined symbol: __SEGGER_init_zero
1> error: undefined symbol: __SRAM_segment_end__
1> error: undefined symbol: __bss_end__
1> error: undefined symbol: __bss_start__
1> error: undefined symbol: __ctors_load_start__
1> error: undefined symbol: __data_end__
1> error: undefined symbol: __data_load_start__
1> error: undefined symbol: __data_start__
1> error: undefined symbol: __dtors_load_start__
1> error: undefined symbol: __fast_end__
1> error: undefined symbol: __fast_load_start__
1> error: undefined symbol: __fast_start__
1> error: undefined symbol: __rodata_end__
1> error: undefined symbol: __rodata_load_start__
1> error: undefined symbol: __rodata_start__
1> error: undefined symbol: __stack_process_end__
1> error: undefined symbol: __stack_process_start__
1> error: undefined symbol: __text_end__
1> error: undefined symbol: __text_load_start__
1> error: undefined symbol: __text_start__
Build failed

It seems I should keep the Segger_thumb?

But then I get errors:

Building ‘twi_master_using_app_twi_pca10028_sdk12’ from solution ‘twi_master_using_app_twi_pca10028_sdk12’ in configuration ‘nrf51422_xxac’
2> Assembling ‘SEGGER_THUMB_Startup.s’
1> Linking twi_master_using_app_twi_pca10028_sdk12.elf
1>
1> Diagnostics:
1> error: multiply defined global symbol _start
1> error: defined by thumb_crt0.o
1> error: and by SEGGER_THUMB_Startup.o
1> remark: increasing alignment of section .vectors from 1 to 2 because it contains executable instructions
1> error: undefined symbol: __SRAM_segment_end__
Build failed

Rob

RE: How to redirect printf to UART when using Segger Embedded Studio

AndreasF — Wed, 20 Feb 2019 08:44:19 GMT

Hi.

Can you use the files system_nrf51.c and system_nrf51.h found in \components\toolchain

Download this zip file:devzone.nordicsemi.com/.../embedded_5F00_studio.zip

And place it like I have on my picture, in \components\toolchain

Inside this file is a flash_placement.xml, ses_nrf51_startup.s and thumb_crt0.s which should work.

Best regards,

Andreas

RE: How to redirect printf to UART when using Segger Embedded Studio

northernLight — Tue, 19 Feb 2019 11:44:28 GMT

Hi Andreas

Thanks for the prompt. I followed the tutorial importing the Keil project from examples/periperals/UART/blank - target NRF51822 QFAA

However I do not remember modifying the internal files after the import. Which ones should I use for this SoC?

The tutorial is based upon the 52 series

Rob

RE: How to redirect printf to UART when using Segger Embedded Studio

AndreasF — Tue, 19 Feb 2019 07:15:13 GMT

Hi Rob.

How did you exactly set up the project in Segger Embedded Studio, did you follow this tutorial?

Best regards,

Andreas

RE: How to redirect printf to UART when using Segger Embedded Studio

northernLight — Mon, 18 Feb 2019 22:36:00 GMT

After much checking I founder these helper instructions (from the disassembler window)

--- SEGGER_THUMB_Startup.s -- 393 --------------------------
bx lr
HELPER __getchar
JUMPTO debug_getchar
HELPER __putchar
JUMPTO debug_putchar

However removing the HELPER lines from thumb_crt0.s and crt0.s made no difference to printf nor putchar() which still direct to the debugger terminal. Doh!!!

Point taken on the invisible powers of the optimiser.

Any ideas on what should I try next?

Rob

RE: How to redirect printf to UART when using Segger Embedded Studio

awneil — Mon, 18 Feb 2019 14:15:26 GMT

[quote userid="76628" url="~/f/nordic-q-a/43790/how-to-redirect-printf-to-uart-when-using-segger-embedded-studio/171652"]it does consume stack space for an unnecessary nested call[/quote]

Does it?

The optimiser may well be smart enough to avoid that ...

RE: How to redirect printf to UART when using Segger Embedded Studio

northernLight — Mon, 18 Feb 2019 13:48:52 GMT

Andreas,

Thankyou for thinking about this. I have been using the UART example in /peripherals, not the ble one. I am compiling the example using Segger Embedded Studio which I suspect defines the behaviour of printf in a non-helpful way (at least to me).

From the Segger manual:

https://studio.segger.com/index.htm?https://studio.segger.com/ide_property_code_help.htm

Sending all output to the SEGGER Embedded Studio virtual terminal

You can send all output to the SEGGER Embedded Studio virtual terminal by supplying the following implementation of the__putchar function in your code:

#include <debugio.h>

int __putchar(int ch)
{
  return debug_putchar(ch);
}

This hands off output of the character ch to the low-level debug output routine, debug_putchar.

Whilst this is an adequate implementation of __putchar, it does consume stack space for an unnecessary nested call and associated register saving. A better way of achieving the same result is to define the low-level symbol for __putchar to be equivalent to the low-level symbol for debug_putchar. To do this, we need to instruct the linker to make the symbols equivalent.

Select the project node in the Project Explorer.
Display the Properties Window.
Enter the text __putchar=debug_putchar into the Linker > Linker Symbol Definitions property of the Linker Options group.

Maybe this redirection has already been configured in the standard install of SES. (I am using the most recent version of SES). I will check and come back

Any thoughts?

Rob

RE: How to redirect printf to UART when using Segger Embedded Studio

AndreasF — Mon, 18 Feb 2019 08:54:47 GMT

Hi.

I'm a bit unsure what you mean by this question.

The UART example in SDK 12.3 (\examples\ble_peripheral\ble_app_uart) have a printf call in main(void) which prints "UART Start!" to UART.

You can see it here:

Can you please explain more details?

Best regards,

Andreas