Debug+trace connector for SiLabs EFR32BG22

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    • Debug+trace connector for SiLabs EFR32BG22

      New

      Hello,

      I am trying to build the 19 pin debug+trace connector for a Silicon Labs EFR32BG22.Here is the link to the reference manual for that part:

      silabs.com/documents/public/re…-manuals/efr32xg22-rm.pdf

      (Please do not think I expect you to read this, it is only for reference)



      I used this link to describe the debug+trace connector:

      wiki.segger.com/19-pin_JTAG/SWD_and_Trace_Connector



      Here is the connection list I have created:

      Name
      		 EFR32BG22
      		 Pin
      		 Pin
      		 EFR32BG22
      		 Name
      VtargetReference
      		 1.8 Volts
      		 1
      		 2
      		 PA02
      		 TMS/SWDIO
      Ground
      		 3
      		 4
      		 PA01
      		 TCK/SWCLK
      Ground
      		 5
      		 6
      		 PA03
      		 SWV
      Blocking Key
      		 NC
      		 7
      		 8
      		 NC
      		 TDI (Test Data Input) JTAG pin, not used for SWD
      Not used
      		 NC
      		 9
      		 10
      		 nRESET
      		 Reset pin
      USB5V0
      		 target power
      		 11
      		 12
      		 PA04
      		 TRACECLK
      USB5V0
      		 target power
      		 13
      		 14
      		 PA03
      		 TRACEDATA0
      Ground
      		 15
      		 16
      		 NC
      		 TRACEDATA1
      Ground
      		 17
      		 18
      		 NC
      		 TRACEDATA2
      Ground
      		 19
      		 20
      		 NC
      		 TRACEDATA3



      The above table is supposed to look like the 19-pin connector with pins down the middle and connections to EFR32BG22 outside of each pin. As you can see, I am not a good artist.





      Questions:

      • Pin 1 provides a voltage reference for Segger equipment.Is 1.8 volts acceptable?This is my main CPU core voltage and I/O domain.I couldn’t find the electrical specifications for that signal.I see the Supply Adapter has a voltage range of 1.2 volts to 5.0 volts for VTref, is that what Segger equipment allows?


      • On this processor, the SWV pin and TRACEDATA0 pin are shared on the same physical pin (PA03).Will this work for ETM tracing?What does this mean if I am using SWD for debugging?Is the only impact to lose debug printing through the serial wire viewer output pin?

      • I am using a 20 Mhz clock for most work and 39 MHz when Bluetooth is active. My typical usage is to wake up 5 to 10 times per second and run for about 400 microseconds. Do you think the trace buffer will overflow if I only have one TRACEDATA pin?



      Do you have any other recommendations for this?

    • New

      Hi,

      to 1)
      See here:
      segger.com/products/debug-prob…#technical-specifications
      and look for VIF.
      1.2 - 5V are fine for VIF (VTref)

      to 2)
      While it is a bit unusual to shared TRACED0 with SWV because SWV is usually shared with TDO,
      I can see why SiLabs did it.
      As their EFM32 do not support JTAG, there is no TDO signal to be shared with.
      Actually, sharing SWV with TRACED0 is a clever move because you so not lose anything.
      If you enable & use trace, the SWV data is merged into the trace stream and also transmitted via TRACED0-3.
      So when using trace, the SWV pin becomes obsolete.

      to 3)
      Has a fair chance to work with TRACED0 only.
      It heavily depends on the application how good the trace unit can compress the data.
      But I see a 39 MHz CPU speed not really as critical.
      Do you know the source of the trace clock for these chips?
      Is it 1/2 CPU speed or some “fixed 8 MHz clock”?
      If it is 1/2 CPU speed, 1 trace pin could work with a high chance.
      Please read the forum rules before posting.

      Keep in mind, this is *not* a support forum.
      Our engineers will try to answer your questions between their projects if possible but this can be delayed by longer periods of time.
      Should you be entitled to support you can contact us via our support system: segger.com/ticket/
      Or you can contact us via e-mail.

    • New

      Alex,

      Thanks for your quick reply.

      As far as I know, there is only either the 20 MHz RC oscillator running or the 39 MHz crystal running. We are not using any special clocking like the clock multiplier or divider, one of those frequencies are the main CPU clock when waking up. There isn't any other fixed 8Mhz clock or similar thing on these boards or internal within the CPU. I would assume trace clock is running at half the CPU, or whatever is usual for it.

      We are currently waiting for the connector board to come back to try this on our target board.

      Our application is extremely power sensitive and we spend as much time as possible in low energy sleep.