RTT Viewer not showing data

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    • RTT Viewer not showing data

      I am running the latest version of RTT Viewer (v6.88). I start RTTViewer, connect to an existing session (I am running Ozone v3.20g) and it connects. It will not however show any data. Within Ozone, I can see that the SEGGER_RTT_Write(0, ...) is putting data into the _acUpBuffer, but I never see it in RTTViewer. I can send data from the RTTViewer to the device under test and I see the data arrive in the _acDownBuffer. I also see the device under test consuming this data into our CLI and taking action so I know the input is properly terminated.

      I can also see that the internal data structures indicating that the data has been read, i.e., _SEGGER_RTT.aUp[0].RdOff, is not being updated, so no one is reading this buffer.

      I just can't figure out why I am not seeing the data that is being written into the _acUpBuffer getting read by the RTTViewer. Any ideas?


      The post was edited 1 time, last by software-LE ().

    • Additional information regarding the sudden appearance of this issue for me. I also now have a bootloader and I'm not sure how that might effect the RTT Viewer. I thought that it just looks our at the memory where the _SEGGER_RTT structure is and connects to it, if it's there.

    • Thanks for the reply Alex. I have checked in Ozone's Terminal window and I don't see the data there as well. Additionally, there are pointers in the device firmware's _SEGGER_RTT structure that indicate data has been read by somebody and those pointers are not advancing, so no one is reading the data.
    • I am using a custom board with a ST Microelectronics STM32L451VE microprocessor. The RTT link was working fine until we added a bootloader but the location of the _SEGGER_RTT has not changed in memory. We place it at 0x20000080.
    • Hi,
      Sorry for the delay in response.

      Does the bootloader initialize any low power modes or similar?
      Does it work when specifying the exact address of the control block in the Configuration dialog of the J-Link RTT Viewer?

      Best regards,
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