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µVISION DEBUGGER: Sample buffer size of System Analyzer in MDK µVISION

Information in this knowledgebase article applies to:

  • MDK v5.x


I have added a few global variables to System Analyzer debug window in µVision debug session and I'm using ULINKplus within System Analyzer to measure the power consumption of the target device. After running my program on the target device for a few minutes, the signals captured at the beginning of the execution are truncated and missing in System Analyzer window, as shown in the following figure. What has caused this issue?


The recording data buffer used by System Analyzer is implemented as a ring buffer and has limited size. Different components in System Analyzer has different recording data buffer sizes.

  • Power measurement data (requires ULINKplus): to the date of writing this article, the max time duration of captured data that can be shown in System Analyzer is around 8.5 seconds. When the target device is running for more than 8.5 seconds, only the last 8.5 seconds of power measurement data can be shown in System Analyzer. This limit might change in the future MDK release.
  • Exceptions (requires SWO trace): max 64k exceptions can be shown in System Analyzer.
  • Value changes of VTREGs or variables (requires SWO trace): max 4 VTREGs or variables when debugging a Cortex-M target device, because of the limited number of HW watchpoints of Cortex-M. Max 64k data samples for each VTREG or variable can be shown in System Analyzer.
  • Incoming events from Event Recorder: all events captured and shown in Event Recorder debug window.
  • Core Clock measurement (requires ULINKplus): max 64k data samples can be shown in Event Recorder debug window.


Last Reviewed: Wednesday, September 11, 2019

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