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mangobay11
Associate II
August 28, 2024
Question

SWO outputs only works with HSI enabled for SYSCLK, not HSE

  • August 28, 2024
  • 2 replies
  • 645 views

Hi,

 

I am using a STM32F105RC. I was trying to get SWO printf outputs to work, and found that they only work when I configure HSI (8MHz) to be used for SYSCLK, but not when I configure HSE (25MHz) for SYSCLK. I've confirmed that the external oscillator itself is correct.

 

Any ideas would be appreciated, Thanks!

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2 replies

TDK
TDK
August 28, 2024

You'll have to configure the SWV viewer clock rate to match your system clock. In STM32CubeIDE, this is done in the debug configuration window.

TDK_0-1724881769981.png

 

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mangobay11Author
Associate II
August 28, 2024

Hi TDK, thanks for the reply.

I am using OpenOCD. I found that the SWO clock frequency was not set correctly, but I don't understand why.

Anyways, with a core clock frequency of 25MHz and a SWO clock frequency of 2.25MHz I am able to view SWO output

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