[SOLVED] J-Link RTT not working on AM335x

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  • [SOLVED] J-Link RTT not working on AM335x

    Hi,

    I'm trying to set-up the RTT using a J-Link EDU on the BeagleBone Black (AM335x Cortex A8 ), but no data is displayed on the RTT Viewer when using function like SEGGER_RTT_WriteString().

    The J-TAG interface is working as expected (see J-Link Logs.txt),

    Even when the correct address of the SEGGER_RTT_CB struct is passed to the RTT Viewer, nothing happens (see image segger_rtt_memory.png). I also tried to set the SetRTTSearchRanges to scan the entire DDR.

    My config file is :

    C Source Code

    1. #define SEGGER_RTT_MAX_NUM_UP_BUFFERS (2)
    2. #define SEGGER_RTT_MAX_NUM_DOWN_BUFFERS (2)
    3. #define BUFFER_SIZE_UP (1024)
    4. #define BUFFER_SIZE_DOWN (16)
    5. #define SEGGER_RTT_PRINTF_BUFFER_SIZE (64u)
    6. #define SEGGER_RTT_MODE_DEFAULT SEGGER_RTT_MODE_NO_BLOCK_SKIP
    7. #define SEGGER_RTT_IN_RAM 1


    When the the SEGGER_RTT_WriteString(0, "Hello from RTT!\n"); is executed, the string is copied to the correct memory location pointed by p->aUp[0].pBuffer (see image segger_rtt_bufferup.png).

    Any help would be appreciated

    Best regards
    Alexandre


    Source Code

    C Source Code

    1. #include <stdio.h>
    2. #include <stdbool.h>
    3. #include "SEGGER_RTT.h"
    4. int main () {
    5. SEGGER_RTT_Init();
    6. SEGGER_RTT_ConfigUpBuffer(0, NULL, NULL, 0, SEGGER_RTT_MODE_BLOCK_IF_FIFO_FULL);
    7. SEGGER_RTT_WriteString(0, "Hello from RTT!\n");
    8. }




    J-Link Logs.txt

    The post was edited 1 time, last by alexandre.burry ().

  • Hi Alexandre,


    as described on the website, J-Link RTT is supported by all devices/cores with background memory access.
    Unfortunately, Cortex-A8 does not support this feature.

    Best regards,
    Niklas
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