Retarget printf on STM32G070RBxx Cortex M0+

[AVerm.4]

Hi,

I'm trying retarget printf. My uart_write function is working correctly and i'm able to see character on Teraterm.

But when i try to use printf it is not working. i even tried semihosting to execute printf but it fails. i'm attaching the screenshots -

Disassembly of the code stucks at "bkpt 0x00ab" -

any solution for this problem? 

[KDJEM.1]

Hello @AVerm.4 ,

 

I recommend you to refer to this FAQ: How to redirect the printf function to a UART for debug messages and follow the steps.

This article describes how to redirect the printf output to the STM32 UART peripheral that is connected to the UART pins on the embedded ST-Link that will be transmitted to the host computer and displayed via a windows terminal program, Tera Term using Nucleo-G070RB.

 

I hope this help you!

Thank you.

Kaouthar

[AVerm.4]

Hi @KDJEM.1 ,

I appreciate your comment. But the link provides the way to retarget HAL library UART, which i see is working fine. 

But here I'm using CMSIS library to write my UART driver. And here it is not working.

[Andrew Neil]

---

@AVerm.4 wrote:

the link provides the way to retarget HAL library UART, which i see is working fine. 

But here I'm using CMSIS library to write my UART driver. And here it is not working.

---

It really shouldn't make any difference - they all just end up writing to the UART.

If you're hitting a BKPT instruction, that suggests you're configured for semihosting - you don't want that.

[Andrew Neil]

Please see this for how to capture a screenshot - far better than photographing the screen!

https://www.techrepublic.com/article/how-to-take-screenshots-in-windows-10/

For posting source code, please see the posting tips:

https://community.st.com/t5/community-guidelines/how-to-write-your-question-to-maximize-your-chances-to-find-a/ta-p/575228

 

[AVerm.4]

@Andrew Neil sorry for that. I'm not using a personal computer rather a corporate one were we have limited access to file sharing.!

[Andrew Neil]

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@AVerm.4 wrote:

i even tried semihosting

---

Presumably, the screenshots you shared show your semihosting attempt - as this works via the BKPT instruction?

https://interrupt.memfault.com/blog/arm-semihosting 

 

Instead, follow the Knowledge Base article linked by @KDJEM.1 

And here's a 3rd-party article on the same: https://shawnhymel.com/1873/ 

 

[Andrew Neil]

Just noticed that you are doing this in C++

The linked articles are both just C, and I have just used C.

Could you try this in a plain C project to see if that makes a difference?

 

EDIT:

See: https://community.st.com/t5/stm32cubeide-mcus/stm32cubeide-c-redirected-printf-no-longer-works-how-to-use-cout/m-p/285002/highlight/true#M14943 

 

[AVerm.4]

Tried with the C project as well it's not working.

It printed few lines then threw some garbage. I retried debugging but now nothing displayed on terminal.

Do I need to increase baud rate from 9600 to 115200? Because it's taking time to print.

 

[Andrew Neil]

---

@AVerm.4 wrote:

it's taking time to print.

---

What do you mean by that?

Remember that printf is line-buffered - it won't (usually) send its output until it gets a newline...

stderr isn't buffered:

https://community.st.com/t5/stm32cubeide-mcus/can-t-get-printf-to-work-on-cubeide/m-p/701740/highlight/true#M29337

[KDJEM.1]

Hello @Andrew Neil ,

 

Thank you for this proposal. I reported this request internally. 

Your feedback and request are welcome.

 

Thank you.

Kaouthar 

[Andrew Neil]

Follow-up on retargetting scanf:

https://community.st.com/t5/stm32cubeide-mcus/retarget-scanf-on-stm32g070rbxx-cortex-m0/td-p/721532