# How to debug via printf()?

**URL:** <https://forum.opencyphal.org/t/how-to-debug-via-printf/807>\
**Category:** LibCyphal\
**Created:** [April 21, 2020, 6:37pm UTC](https://forum.opencyphal.org/t/how-to-debug-via-printf/807 "2020-04-21T18:37:10Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![RuslanUrya](https://forum.opencyphal.org/user_avatar/forum.opencyphal.org/ruslanurya/32/467_2.png) [@RuslanUrya](https://forum.opencyphal.org/u/RuslanUrya)\
**Post date:** [April 21, 2020, 6:37pm UTC](https://forum.opencyphal.org/t/how-to-debug-via-printf/807/1 "2020-04-21T18:37:10Z")

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Hello. I have some problems with my node, so i want to see debug information. Library has this functionality. I defined UAVCAN\_DEBUG 1 and UAVCAN\_USE\_EXTERNAL\_SNPRINTF 1 for adding function for embedded system. But, UAVCAN\_DEBUG uses UAVCAN\_TOSTRING, which not supported for embedded systems. What should I do? Thanks!  
I using:  
stm32f303  
UAVCAN v0  
SW4STM32

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**Author:** ![pavel.kirienko](https://forum.opencyphal.org/user_avatar/forum.opencyphal.org/pavel.kirienko/32/9_2.png) [@pavel.kirienko](https://forum.opencyphal.org/u/pavel.kirienko)\
**Post date:** [April 21, 2020, 8:24pm UTC](https://forum.opencyphal.org/t/how-to-debug-via-printf/807/2 "2020-04-21T20:24:30Z")

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This feature is incompatible with embedded systems. I recommend printing things manually. If you are desperate to access private member variables, use the _public morozov_ design pattern.

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**Author:** ![RuslanUrya](https://forum.opencyphal.org/user_avatar/forum.opencyphal.org/ruslanurya/32/467_2.png) [@RuslanUrya](https://forum.opencyphal.org/u/RuslanUrya)\
**Post date:** [April 21, 2020, 9:17pm UTC](https://forum.opencyphal.org/t/how-to-debug-via-printf/807/3 "2020-04-21T21:17:41Z")

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Okay, may be I can use other abilities of the library? For example, via uavcan (log messages)? My node can running and publicating service messages.

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**Author:** ![pavel.kirienko](https://forum.opencyphal.org/user_avatar/forum.opencyphal.org/pavel.kirienko/32/9_2.png) [@pavel.kirienko](https://forum.opencyphal.org/u/pavel.kirienko)\
**Post date:** [April 22, 2020, 9:54am UTC](https://forum.opencyphal.org/t/how-to-debug-via-printf/807/4 "2020-04-22T09:54:18Z")

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Log messages won’t help you here. Roll up your sleeves and output the data you need manually. `UAVCAN_DEBUG` is intended mostly for the developers of the library; it is not supposed to be used in a production application.