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ULINK: Maximum Core Clock for Trace with ULINKpro

Information in this knowledgebase article applies to:

  • ULINKpro
  • MCB1800 Evaluation Board
  • MCB4300 Evaluation Board


I am using ULINKpro sometimes with SWO trace and sometimes with the 4-bit Trace Port. In some applications with higher Core Clocks, trace does not work and I get errors. What is the maximum Core Clock supported by ULINKpro?


The maximum Core Clock which is supported by ULINKpro is 200 MHz. This, and other technical details are specified here.

However, there are a number of issues that can reduce the maximum Core Clock significantly:

  • Limited Pin bandwidth: Many fast microcontrollers only provide a limited bandwidth on the trace pins. For example, NXP specifies a max. core clock of 120 MHz for all LPC18xx/LPC43xx/LPC43Sxx devices when SWO or the trace port is used, even if the port is configured for high-speed mode (EHS bit set). Please see the manual UM10503 on chapter 51.2 on page 1371 for more details.
    Note: In Serial Wire Output - Manchester mode, you can disable the option Autodetect to select the SWO Clock Prescaler manually. This way, you can reduce the resulting SWO clock and the necessary bandwidth without reducing the the Core Clock.
  • Poor PCB Layout: The 20 pin Cortex Debug + ETM connector which contains the trace port signals (4 data lines + 1 clock line) and SWO signal should be located as close as possible to the microcontroller. The traces should all have equal length. No long traces to other components should be connected because this would cause signal reflections and therefore signal distortions.



Last Reviewed: Tuesday, January 12, 2021

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