Peter Voorhees

Embedded Trace Macrocell (ETM) PCB Routing Tips

Discussion created by Peter Voorhees on Mar 16, 2017
Latest reply on Feb 15, 2018 by Peter Voorhees

Hello Community,

We are planning on using ETM to aid in debugging but have found very few routing guidelines for the TRACE_D[0:3] and TRACE_CLK nets.

 

On the K22FX512, using a 120MHz core speed, What is:

  • The clock speed of the TRACE nets? Datasheet says the interface is limited to 50MHz but offers no guidance for determining the speed.
  • Is any particular characteristic impedance for the traces necessary?
  • Do the lines need to be length-matched?

 

Design guild-lines seem to be largely unavailable and the Kinetis datasheets are light on details for this particular functionality. Any help is appreciated. Thanks!

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