Starting the Trace Recorder

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Last updated: Jun 12, 2017
2 min read

Starting the SystemView Trace Recorder

To start recording you need the host application, SystemViewer,  which can be downloaded from the following link: https://www.segger.com/systemview.html

The host application will connect to the embedded target via an onboard or external J-Link and will stream all the trace data up to the PC.

To start a recording open the SystemViewer host application and click the key F5 or Target -> Start Recording and you will be presented with the dialog window shown on the right hand side.

Before pressing the OK button make sure that you have confirmed the following settings:

  • The Target Device name matches your embedded target and the one configured by other tools using the same J-Link session (e.g. Debugger and/or µC/Probe).

  • The Target Interface & Speed match the ones supported by your embedded target and the ones configured by other tools using the same J-Link session (e.g. Debugger and/or µC/Probe).

  • The RTT Control Block Detection setting makes an attempt to locate the symbol _SEGGER_RTT where the trace data is stored using one of three methods: automatically or by manually specifying the address and range of _SEGGER_RTT

     

Recording Status

During the streaming process, you will be presented with a window similar to the one shown on the right hand side.

Two categories in that window Events and RTT will display any potential Dropped Events due to Overflows in the communication.

Overflow events occur when the SystemView RTT buffer in the embedded target is full.

This can happen due to the following reasons:

  • J-Link is kept busy by another application using the same J-Link session and cannot read the data fast enough.
  • The embedded target interface speed is too low to read the data fast enough.
  • The embedded application generates too many events to fit into the buffer.

To prevent this:

  • Minimize the interactions of the debugger with J-Link while the embedded target is running. (i.e. disable live watches)
  • Select a higher interface speed in all instances connected to J-Link. (e.g. The debugger, µC/Probe and SystemViewer)
  • Choose a larger buffer for SystemView. (1 - 4 kByte)
  • Run SystemViewer stand-alone without a debugger and/or µC/Probe.

 

Further Reading

For additional and more detailed coverage of SystemView refer to SEGGER SystemView Documentation.